Risk Factors | Cancer Prevention Institute of Canada

Interventions to reduce energy intake mostly relate to various types of diet change, and especially to modified fat or sugar intake. Diet and nutrition have been a focus of extensive research for a number of decades. Working out the scientific details of the biology of food, its biochemical constituents, and their relationship to metabolic functions, has been a major research interest. The actual application of the insights to individual and public consumption practices, however, has been at a lower level of intensity, with the notable exception of a perennial interest in losing weight. Resistance to the widespread adoption of dietary changes may be due to the relatively poor track record of reducing consumption of certain food groups in order to produce a sustained weight loss. There actually is an inconsistent evidence base for several proposed dietary interventions.[1] For example, the best known population-based campaign, promoting 5 A Day vegetable and fruit servings in the US, has produced what can only be described as equivocal results (see below).

The Canadian and B.C. Diet

Statistics Canada tracks the average diet of the population each year. Red meat and poultry consumption was basically unchanged in 2003 over 2002. Milk consumption overall declined, though more cream was consumed (possibly a result of the growing popularity of caffeinated beverages). Rice consumption increased modestly, continuing a trend; the ingestion of other cereal, and especially wheat flour, products has greatly increased over 10 years, though they were slightly depressed in 2003 (perhaps the “low carb diet” effect).

Canadians ate more fruit, and though vegetable consumption is also rising, potatoes count for nearly half the amount. Surprisingly, fish consumption dipped slightly in 2003, the opposite of the trend over the preceding 10 years. Most tellingly, the overall ingestion of energy-dense oils and fats continued to rise, as did the total consumption of food. The “good news” in this pattern is that the recommended requirement of many lipids, vitamins and minerals is being regularly met, but the price is caloric consumption, which has been rising 1 to 3% year-over-year in the last decade.[2] Although the average young adult needs about 2500 kcal per day (more in men, less in women),[3] according to Health Canada the average caloric intake for the whole population has been significantly higher, and climbing, since 1995.[4] One factor consistently implicated in weight gain is the increasing consumption of energy-dense, sugary beverages such as soda pop, especially among youth.[5]

A comparison with the BC Nutrition Survey (BCNS) from 1999 for food group consumption is instructive, especially in regard to our vegetable and fruit target. This was the first such comprehensive survey conducted in BC since the Nutrition Canada Survey in the 1970’s. The recently published report on the data showed a somewhat lower percentage of the BC population consuming “5 a day” servings of vegetables and fruit when compared with 2000/01 Canadian Community Health Survey (CCHS) data for the province (35.4 versus 40.1%).[6] The BCNS concurred with the positive picture derived from the CCHS concerning average daily servings; though the majority of adult British Columbians did not meet the minimum recommendations for vegetable and fruit intake, in many cases they only needed to add one or two servings per day to meet that goal. This suggests the encouraging conclusion that positive movement towards the 2010 target for vegetable and fruit consumption is well within the realm of possibility.

Dietary Change

The dietary goals seen in the most common interventions in clinical care and / or public health programs have included:

These intervention categories coincide with Canadian dietary guidelines, as well as recent nutritional risk factor targets in developed countries, e.g., Healthy People 2010 in the US.

The clinical application of limiting overall calories or specific energy-dense foods will be a focus of this subsection of the report, as will be other sorts of setting-specific programs and wider environmental policies directed towards healthy eating and reducing unhealthy weight.

In terms of individual behaviours, the effectiveness of low-calorie and low-fat diets will be reviewed here in the context of healthy weight maintenance as well as some other beneficial effects. The remaining dietary goals, which involve increasing the consumption of reportedly health-enhancing foods, have mostly been applied at population levels, e.g., the well-known promotion of 5 A Day, or 5 daily servings of fruits and vegetables.[7] The goals will receive a more cursory treatment insofar as they only have a tangential impact on weight control.

Community-based Interventions

Community-wide dietary interventions are sometimes referred to as nutrition education; when behaviour change is intended, the common label is nutrition promotion. The most popular framework for health promotion strategies is social marketing, or the adaptation of commercial marketing to the planning, execution, and evaluation of programs to influence the behaviour of target audiences in order to enhance personal and societal welfare.[8]

Multimedia Campaigns

Multimedia campaigns related to dietary change are a major component of nutrition promotion. They exhibit substantial heterogeneity: there are many different media available, the campaign can vary in intensity and duration, messages can range from basic health / nutrition information to more sophisticated prompts for dietary behaviour change, and the intervention may be part of a multi-component strategy looking at more than one risk factor. The multiple interventions in the latter case naturally make it difficult to isolate the effect of mass media.

Many doubt whether mass media campaigns, in the absence of other programming, can create sustained behaviour change.[9] A similar conclusion was recently reached concerning the popular health education strategy of nutritional labels on processed foods. An extensive body of literature underlines that, while using the labels is associated with lower intakes of total fat, saturated fat and cholesterol, the very “consumer use” which is key to the equation is

influenced by determinants requiring other interventions. For example, people with high intake of fat do not search for nutritional information as much as healthy eaters do, providing an interesting “catch 22” for public health planners.[10] In spite of these obstacles, the amount of money which is poured into tobacco, food and other advertising provides circumstantial support for continuing to develop effective counter-marketing tools. If it did not work, corporations would not continue to invest billions of dollars in advertising.

There are few studies that have tested the validity of the suggestion just made, that is, whether mass media campaigns for diet change are effective by themselves. Two different studies in West Virginia demonstrated that paid advertising alone was able to change milk-drinking habits towards fat-reduced products, though the effect was not sustained after the campaign ended. In one study, the city where the advertising occurred showed 13% of the population temporarily switching to 1% milk, compared to 7% in the control city. The study also noted that more intensive public relations or social marketing in a third city produced a 20% switch rate.[11]

The most impressive dietary results have been in programs that offer a consistent message over a long period, e.g., the famous 30- year health behaviour project in North Karelia, Finland, where, among other changes, fat consumption and cardiovascular disease have been dramatically reduced.[12]

Vegetables and Fruit
Dietary interventions directed at widespread “free living” populations can be tested through before-and-after surveys, though it is difficult to control for confounding variables.[13] This approach has been used with the 5 A Day campaign, the prototype of which began in California in 1988, but which is now spread throughout the US. Versions of the US campaign now exist in many other countries.[14] The Canadian program is called 5 to 10 a Day for Better Health.[15] Although based on the principles and practices of social marketing, the various vegetable and fruit campaigns most typically depend on a mass media effort, thus allowing a partial test of that approach. Other components of the community-wide social marketing approach have included enhanced public relations, point-of-sale promotions, nutrition labelling, cookbooks, and sponsorships, as well as initiatives in schools, workplaces and churches (see below).

Studies have definitely shown that the message got out; for example, awareness in the US of the need for 5 daily

servings of vegetables and fruit rose from 7% in 1991 to 19% in 1997.[16] The real test, though, is actual consumption patterns. On the one hand, randomized community intervention research trials of the program in the US have consistently shown an increased consumption of servings ranging from 0.2 to 1.7 per day. An analysis which adjusted for demographic shifts, however, concluded that there had been no significant changes.[17] This is confirmed by the major US risk factor surveillance system, which showed little change in nationwide vegetable and fruit consumption between 1994 and 2000.[18] Some research work done more in the economic sphere has also cast doubt on the impact of advertising on vegetable sales.[19]

Other components which are sometimes part of a community-wide program for vegetable and fruit consumption have been investigated:

Conclusion
A recent meta-analysis of health communication campaigns in the US showed that they have small measurable effects in the short term.[23] This general conclusion is borne out by the results of nutrition promotion campaigns (though the data is very limited). For example, a review noted that the best result expected for an unselected population was 1 to 4% reduction in fat contribution to overall energy.[24] It should be noted that such changes are still useful, and across a whole population may represent a significant public health benefit.

With an understanding of the potential benefits of even a small impact, new strategies within mass media and other community-wide delivery systems may still be worth pursuing. The reality for now, though, is that increased awareness of nutrition principles and recommendations is the most common result of such campaigns, with behavioural change being more elusive, especially once the intervention ceases. The greatest changes are seen, not surprisingly, in subpopulations which are selected for some degree of social cohesion and peer support, e.g., in schools (see below) and churches,[25],[26] or which are otherwise specially motivated, e.g., people at high risk of disease. Within highly educated and motivated groups, fat intake has been reduced by 10 to 16% of energy, 3 to 4 times the rate seen in unselected groups.[27]

One explanation offered about the success rate in Finland as described above, especially compared to similar US projects, is that there was a relatively high rate of community initiation and participation.[28] Another idea is that the program achieved the ultimate goal of the “diffusion of innovations theory,” that is, reaching a critical mass where the message and behaviour impact has a self-sustaining momentum. It should be noted, however, that even sustained changes in the intervention group often are equalled in the long-term by changes in the control group of a study.[29] The Finnish project is further complicated by the confounding factors commonly encountered in epidemiological studies.

Appropriate Meals Available at Restaurants

With the increasing frequency of “eating out” in developed countries (some estimates put the Canadian rate at about 5-6 times every week), focusing on the menu choices in restaurants makes good intuitive sense.

Restaurant food tends to contain more fat and saturated fat, and less fibre,[30] and expanded portion size has also been a growing concern.[31] The menu assessment tools,[32] proposed legislation for nutritional labelling on menus, and other interventions are still being developed.

Outcome studies are in their infancy.[33] For example, one recent project looked at whether a promotional campaign could influence the sale of heart-healthy menu items; the slight increase in such sales was found to not be statistically significant.[34]

Another strategy is Eat Smart!, Ontario’s program to encourage, among other health practices, good nutritional choices on menus; awards of excellence are given to establishments which meet standards. A similar program in Australia is also being applied to childcare center menus.[35] There is limited and somewhat dated evidence that labelling the healthy choices on menus can increase sales of those items.[36]

Access to Fast Food Restaurants

The broader environmental situation regarding restaurants has also been investigated. One recent US study showed that the number of fast food establishments in African-American neighbourhoods was 50% higher than in white ones. Similar results were found when comparing against neighbourhood income levels: the lower the median income, the higher the concentration of fast food restaurants.[37] There is a clear link with the earlier commentary concerning high obesity rates in low income families: the energy-dense, low-cost food in such establishments appeals to those with less disposable income. Fast food consumption in turn has been strongly linked to obesity.[38] The planning tools to construct an intervention for such socio-ecological risk factors are not yet clear, nor have health outcomes from such disparities been fully assessed so as to allow the priority and urgency of response to be determined. What is clear is that the same socioeconomic forces reinforcing health inequities are at work in determining the range of food available in neighbourhood restaurants.

Portion Sizes

The issue of large portion sizes has been on the public health agenda for some time. Leisure and disposable income in developed countries, and certain segments of the population in developing countries, allow for such overeating habits, which in turn have been linked to rising obesity. Furthermore, any individual behavioural tendencies are probably reinforced by environmental conditions (e.g., relatively low food prices and the availability / marketing of large, even “super-sized,” restaurant meals).[39] Although the issue is becoming increasingly apparent, the appropriate responses are less so; even given the unlikely scenario of fast food restaurants having legislated meal sizes, it is hard to imagine how individual consumers could be prevented from ordering a la carte or simply consuming multiple meals.

A more effective approach for weight control related to portion size may be to increase fibre in the diet, in particular vegetable and fruit consumption.[40] Aside from other health benefits, good intuition would suggest that filling up on high-fibre foods of low energy density but high satiation might preclude overeating other types of foods that are less healthy.[41] However, research evaluating “reduction” strategies for dietary change against more positive “substitution” strategies is at an early stage.[42]

Low-cost Fruits & Vegetables in Low-income Communities

In Canada, a report from 2003 suggested that access to vegetables and fruit (and milk products) may be constrained in low income families.[43] Personal economics are not the only barrier.[44] Various studies have shown that the range of healthy food available in stores is smaller in low-income areas; as well, proximity and access to the stores was poor.[45]

One study showed that ease of access to a supermarket increased daily household fruit consumption by 84 g per adult.[46] Most of this research has been conducted in the US. One intervention proposed in that jurisdiction has been to regulate stores licensed to receive WIC (Women's Infant & Children) Supplemental Food Program coupons, requiring them to provide a certain minimum display of fresh vegetables and fruit.

Other supermarket-based interventions have been suggested which are potentially useful in a variety of neighbourhoods:[47]

A store in one of Winnipeg’s poorest neighbourhoods provides fruit baskets at subsidized prices that children can afford as an alternative to purchasing candy.[48]

Few of these strategies have been rigorously evaluated. Studies that have been conducted have shown positive

results for measures such as consumer knowledge, but provided little data on consumption patterns themselves. The positive affect of pricing in settings such as schools suggest that this may be a fruitful avenue of intervention. This is especially significant considering that diets high in fat and sugar usually represent a low-cost option to consumers, whereas healthy diets tend to cost more.[49]

Commercial Diet Programs

Although technically not part of public health, the very popularity of various off-the-shelf diet plans and support programs has generated some research. One 2004 review of well-known programs showed that weight loss certainly was possible over the short term with the various options, depending on the participant.[50] But there was wide variation in the weight loss experienced, and the difference between the approaches was small on average. The main caution about these interventions, as with self-help dieting, is the frequent experience of relapse. A 2005 review confirms that the evidence of effectiveness for commercial programs is suboptimal,[51] except for Weight Watchers; it is the one commercial approach that has recently been found to have a significant effect for up to 2 years.[52].

Workplace-based Interventions

Interventions in workplaces to affect diet are at an early stage, especially compared to the number of smoking cessation programs in the same setting.

Dietary Fat
The 1997 review[53] in the UK mentioned earlier found only 4 high quality studies, a total which has not appreciably changed since then. The most effective projects for fat reduction focused on changing diet (and sometimes serum cholesterol levels) rather than multiple risk factors. They also usually included individual screening and counselling. One study conducted at 16 sites showed a reduction in fat intake of 1% of energy.

Vegetables and fruit
The Australian review noted earlier found 2 studies which provided findings for vegetables and fruit. The increase in consumption reported amounted to 0.1 to 0.5 servings per day.[54] The elements of effective interventions include:

School-based Interventions

School programs to create dietary change have highly variable components from study to study; typically they draw from one or more of the following: curricular material, school-wide events such as assemblies, contests, snack breaks, posters and related communication methods, and changes in cafeteria menus. Recruiting parent and teacher involvement is also common. It is important to distinguish the traditional public health strategy for eating behaviour change which has focused on individual awareness through educational approaches from the more recent appreciation of environmental influences on dietary choice.[55], [56],[57],[58] These influences include food availability, price, promotion, role modelling, and more diffuse social norms. Environmental approaches can be thought of as those that do not require the individual to actively select themselves into the program.[59]

Educational Content

The majority of controlled studies found in one 1997 review of health promotion programs were set in schools or universities, though the studies were mostly perceived as poor quality. Most of the programs were directed at children aged 8 to 12.[60] The small number of reliable post-secondary studies included in another review from 2004 were at least 10 years old, and one dated from 25 years ago.[61]

At the younger age level, two programs have been noted, CATCH and Know Your Body, which decreased fat intake by 2 to 3.5% of energy, within the range seen for typical community-wide programs. In general, the most effective interventions in schools included these features:

Most of the studies found by an Australian review in 2000 were from the US and involved low-income children aged 9 to 11.[62] Of the 16 studies examined, 14 achieved a positive effect for either vegetables and fruit or fruit alone. The change ranged from +0.20 to 0.77 servings per day. The studies were heterogenous in quality. The one intervention showing the largest reliable impact included these elements alongside the curricular component:[63]

The more comprehensive the program, the more difficult it is to isolate the components that have been particularly effective. A few studies have looked at discrete interventions, some of which show promise and all of which need further research:[64]

Cafeteria Practices

A 2003 review, updating the few additional studies published since the Australian report noted above, generally agrees with the positive assessment of school-based interventions for vegetable and fruit consumption; fruit consumption has been especially enhanced, with increases ranging from 0.2 to 0.6 servings per day.[67]

This more recent review also includes an expanded treatment of stand-alone environmental influences, including 3 studies focusing on vegetables and fruit and 4 which had a different main focus, namely, dietary fat, but which also measured vegetable and fruit consumption.

The primary focus of environmental interventions in schools has been cafeteria practices, for example, the pricing strategy noted above; some results have been promising, but in one 2004 study Perry and colleagues reported on a cafeteria intervention which only showed very modest gains, mainly related to fruit. Their conclusion, based on this and other work, is that the multi-component programs described above are more potent than stand-alone cafeteria strategies.[68] This is the same conclusion reached by the US Agency for Health Care Research and Quality in 2001.[69]

Vending Machines and Other Food Choices

Even if only part of the prevention story, the environmental approach to “healthy schools” is becoming a stronger feature of planning and research.[70] For instance, vending machines are increasingly a target. One recent Minnesota study showed that only a third of school vending machine items qualified as low-fat.[71] A 2003 report by the BC Provincial Health Officer noted that 90% of middle and high schools sell soft drinks, with about 10% having exclusive contracts with manufacturers. [72]

There is increasing concern about soft drink consumption, especially in association with childhood obesity, though the evidence is not conclusive.[73],[74],[75] Nevertheless, New York City recently banned all sweetened drinks and snacks from school vending machines; a ban has been recently instituted for elementary schools in Ontario, and is being considered in B.C.[76] Such initiatives are still relatively new, and the evidence base for dietary (and other health) effects is not yet well-developed.

Other researchers are pursuing incentives rather than bans, for instance, the effect of pricing on food choices.[77],[78] One study from 2001 showed that reducing the price of low-fat snacks in vending machines by 10, 25 or 50%

increased sales of those items by 9, 39 and 93%, respectively; another pertinent result is the fact that profits per machine were not affected.[79] This study updated and confirmed earlier work by the same authors.[80] Recent research in the context of a teacher lounge showed that increasing the availability of low-fat items in vending machines and adding some promotional material increased sales of such items, though the results were deemed to be suggestive rather than statistically significant.[81]

In general, one study showed that price decreases may be a more powerful incentive to choose healthy food than, say, health messages.[82]

Home-based Interventions

Family-oriented weight loss treatments have been studied in comparison with individual approaches. This usually involves recruiting family members to participate together in a weight loss program, or otherwise engaging the family or friends of a subject to play a supportive role.

The results have been mixed. In 1992, for example, a group of Mexican American women were randomly assigned to a control group (basic information distributed), individual group (information plus in-class training), or family group (spouses and children attended the classes as well). Although both intervention groups lost significantly more weight than the control, there was no difference between them.[83]

A study published in 1999 was more promising: individuals recruited with 3

friends or family members for a 4-month behavioural treatment maintained their weight loss at 6-month follow-up at almost 3 times the rate of subjects recruited individually.[84] Pooled results from 4 studies showed an overall increased weight loss of almost 3 kg with social support.[85]

In spite of the equivocal evidence, many jurisdictions are persuaded that a focus on the family is vital for obesity control, especially in children.[86],[87] This was in part the motivation behind the major report Healthy Weight 2008 Australia’s Future: The National Action Agenda for Children and Young People and their Families.[88]

Clinical Interventions and Management

Brief Advice

The brief physician advice which is most feasible in the primary care setting is enhanced in effectiveness when combined with self-help materials and interactive communications such as telephone follow-up. Such minimal interventions should not be underestimated. One RCT found that merely giving people a one-sentence assessment of their fat intake as a percentage of total energy was enough to create significant decreases in fat consumption.[89] As with smoking cessation, physician advice to change exercise and dietary habits is reported to be a strong predictor of motivation and attempts to change.[90]

Counselling

Apart from the patient education related to diet, which is sometimes called “nutritional counselling,” there are many different types of true psychological intervention used directly for weight control. Behaviour therapy and cognitive behaviour therapy seem to be the methods of choice.[91] They can be used by physicians or by other members of the healthcare team to which an overweight person may be referred.

Behavioural treatments aim to provide the individual with coping skills to handle various cues to overeat and to manage lapses in health-enhancing diet or physical activity; therapeutic techniques include goal-setting and self-monitoring.[92]

Cognitive strategies, on the other hand, seek to identify and modify aversive thinking patterns and mood states.[93] When combined, the two forms of therapy appear to improve weight loss and prevent regain.[94] The Cochrane review in this area is still in process. It notes that counselling appears in major clinical guidelines for obesity control mostly because “diet and exercise combined with psychological interventions comprise an intuitively powerful weight loss program.”[95]

Unfortunately, the evidence base for this claim is limited. There are still major gaps in knowledge concerning diet, physical activity, or a combination of the two in structured or “lifestyle” approaches, and the specific role and benefit of counselling, whether behavioural, cognitive, person-centred, or even full-fledged psychoanalysis.The counselling delivery mode has also not been well-investigated, though preliminary research suggests that group interventions may be at least as effective as individual ones, presumably due to the benefits of social support.[96]

Nutritional counselling is distinguished by a direct focus on diet for a variety of health benefits, which often includes weight loss. A comprehensive review of counselling for healthy eating was undertaken for the US Preventive Services Task Force in 2003.[97] A total of 21 studies met the eligibility criteria, e.g., following an RCT design; 17 of the studies looked at dietary fat, 10 at vegetables and fruit, and 7 at dietary fibre.

Counselling for reduction of total saturated fat was effective in all cases, and showed medium-to-large decreases in 12 studies. In the 9 studies that specifically measured change in percentage of calories from saturated fat, net reductions ranged from 0.9 to 5.3%. To put this in context, the upper limit of this range represents a reversal of the increased calories from fats and oils over 10 years in Canada.

Of the 10 studies focusing on vegetable and fruit consumption, 8 showed only small to medium increases (<0.8 servings per day), though in some cases this would be enough to move an individual into the range of recommended “dosage.” The two studies with large effects increased consumption by 1.4 and 3.2 servings.

Counselling for increased dietary fibre produced small positive effects (0.3-1.6 g per day) in 5 studies, with the remaining 2 projects showing net changes of about 3 g per day at 1-year follow-up (and 6 g for women in one case).

The literature examining the effect of dietary counselling in primary care and other settings is complex. For example, there are many possible counselling components, including dietary assessment, self-help materials, interactive reinforcement (computer-tailored mailings, telephone counselling), small groups, family involvement or other social support, and goal-setting. The characteristics of the most successful interventions were:

One of the main limitations, common to most risk factor interventions, is the scarcity of long-term outcome data with respect to counselling and diet. Given that, even the modest impacts of counselling on dietary change seen in this review need to be treated with caution.

A comparison of individual and group-based treatment has also been the focus of a small number of trials. The results show a very modest benefit in weight loss with group programs over shorter follow-up (e.g., 0.74 kg at 18 months), but an opposite effect later (e.g., smaller weight loss in group settings after 5 years).[98]

Dietary Treatment

Sometimes behavioural changes aimed at weight loss are encapsulated in a “dietary prescription” which is often supported by various types of counselling. The general results of this classic approach have not been encouraging; the pattern usually seen is moderate weight loss, followed by gradual weight regain.[99]

The only completed Cochrane review related to diet examined low-fat approaches in comparison with classic low-calorie options. A small number of studies were included which provided results at 6, 12 and / or 18 month follow-up. There was no significant difference in weight loss between the two diets at any point, nor for other outcome measures such as serum lipids, blood pressure and fasting plasma glucose. The conclusion was that fat-restricted

diets are no more effective than calorie-restricted ones in achieving long-term weight loss.[100]

For reasons that are not clear, the Health Technology Assessment (HTA) program in the UK only looked at one of the studies which compared low-fat and low-calorie diets, noting that there was a modest benefit for the low-fat approach.[101] The RCTs comparing these diets to no intervention controls actually leaned in the opposite direction, giving an edge to the low-calorie approach, so the final conclusion about the optimum weight loss plan remains unclear. However, the overall impact is clear: reducing calories by any means produces a weight loss (providing energy expenditure is not decreased).

Two of the low-fat diet studies also reported prevention of type 2 diabetes onset, as well as reduced use of hypertension drugs. The HTA notes that the low-fat category contained the greatest number of RCTs, and it is the diet most commonly recommended in the UK.

Given the small number of studies, HTA did not ultimately find sufficient evidence of benefit for low-calorie or very low-calorie diets versus control. Three RCTs comparing these two approaches generally revealed no significant difference in effectiveness. It is worth noting, however, that the greatest weight loss of any study was seen in the case of one very low-calorie diet with a small sample of obese patients.[102]

The HTA did find a significant short-term improvement in weight loss with a protein-sparing modified fast versus a low-calorie diet (3.57 kg at 12 months), but the effect disappears over longer follow-up; at 18 months the weight loss was 0.69 kg, and there were no statistically significant changes in blood lipids.

The current popularity of modified low-carbohydrate diets undoubtedly will prompt a systematic review of the growing literature on such interventions, some of which seems to be supportive of the health benefits of a low-carbohydrate intake.[103]

Approved Drug Treatment

Two main drugs have been approved in Canada, the US and other jurisdictions for long-term treatment of unhealthy weight: orlistat and sibutramine. Orlistat reduces fat absorption from the intestine, and hence caloric intake, by inhibiting gastrointestinal lipases. Sibutramine is an appetite suppressant, thought to work via norepinephrine and serotonergic mechanisms in the brain. It reduces food intake by producing a feeling of satiety. These two drugs are normally only recommended for obese patients, or those overweight and with significant comorbidities.

Both drugs have significant side effects. Orlistat may reduce the absorption of fat-soluble vitamins (A, D, E) and nutrients; as well, there can be gastrointestinal problems associated with fat malabsorption, unless fat is restricted in the diet while taking the drug. Sibutramine may increase blood pressure and induce tachycardia (increased heart rate), as well as cause stroke and disturbances of vision such as eye pain and eye haemorrhage. There were 28 reported adverse reactions associated with the use of sibutramine in Canada from December 28, 2000 to February 28, 2002. As a result, this drug is undergoing a safety review in Canada and in other countries.

Cochrane reviewed 11 RCTs which focused on the effect of orlistat on weight loss as well as on other risk factors.[104] All studies showed greater weight reductions for orlistat plus diet versus placebo plus diet. The average weight loss seen in the pooled data was about 2.9% more with the drug, or 2.7 kg, after 12 months. The weight loss in lower-risk patients was slightly higher.

In the five studies reporting on waist circumference (WC), orlistat consistently produced greater reductions compared with placebo, ranging from 0.7 to 3.4 cm. Pooled results also showed orlistat-treated patients achieved greater reductions in total cholesterol levels by 0.33 mmol/L. Positive results for low density lipoproteins were of a similar order, but more marginal for triglycerides; the high density lipoproteins, which are the “good” cholesterol, were marginally reduced. In addition, nine of the trials showed a decrease in blood pressure with orlistat and five had statistically significant lower fasting blood glucose levels.

In four of the studies, a second year was spent studying weight maintenance. Orlistat-treated patients regained 7 to 22% less weight than those on placebo therapy. Gastrointenstinal adverse events were the most commonly reported, e.g., fecal incontinence in eight of the studies; in the three studies reporting incontinence as a separate end-point, the incidence was 6% higher in orlistat-treated patients. No study reported clinical vitamin deficiency as an endpoint.

A recent review of RCTs confirmed the positive assessment by Cochrane of orlistat’s effectiveness for weight loss and other risk factor reduction.[105]

Cochrane also reviewed three sibutramine weight loss studies, which showed an average reduction of 4.3 kg (4.6%) greater than in placebo therapy after 12 months, or somewhat higher than with orlistat. Sibutramine-treated patients also demonstrated larger reductions in WC (4 to 5 cm), waist-to-hip ratio and body mass index (BMI). Most biomarkers were not significantly different between intervention and control, except for triglycerides (0.18-0.23 mmol/L lower with the drug) and the “good” high-density lipoproteins (marginally elevated). Sibutramine was also tested in two weight maintenance studies, where it performed better than placebo (27% more patients maintained at least 80% of their original weight loss). Adverse effects included statistically significant increases in blood pressure and pulse rates.

The weight loss results for orlistat and sibutramine are consistent with previous health technology assessments which reviewed studies up to June 2000,[106],[107] as well as an assessment dating from May 2004.[108] As well, a meta-analysis of 108 studies in 2002 confirmed that modest weight losses is all one can expect with any drug.[109]

The Cochrane review asks the pertinent question: is the mild degree of weight loss of benefit? Various kinds of studies have shown that even modest weight loss (5 to 10% of original weight) leads to an improvement in cardiovascular risk factors such as high cholesterol and high blood pressure. The results of the Cochrane review are consistent with such findings. What is missing from the literature are RCTs strongly linking weight loss to reduced cardiovascular events and related mortality.[110]

The best evidence for a link between weight loss and reduced disease burden has been in the context of diabetes where lower incidence and associated mortality have been achieved with drugs such as metformin and acarbose[111] over medium-term follow-up periods (2.5 to 3.3 years). The studies showed a modest weight loss, which may have contributed to the preventive effect.[112],[113] The suggestion of these and other studies is that even a small amount of weight loss (less than 5 kg in some cases) can be associated with a significant reduction in the incidence of diabetes (and related mortality), though no direct connection has yet been made (based on RCTs) between weight loss and a reduced burden of diabetes or any other specific disease.

Other Drugs
There are many other weight loss drugs being investigated, especially those in the same category as sibutramine, i.e., suppressing appetite through interfering with the neurotransmission ofnorepinephrine, dopamine and serotonin. Some of these agents are approved for short-term use in appetite suppression, but there are frequent adverse side effects. No high-quality studies exist for any of these products that met the Cochrane criteria of at least one-year follow-up.

Two drugs used in the treatment of diabetes, which is often associated with obesity, have been connected with weight loss. Metformin helps regulate glucose levels and acarbose inhibits the digestion of starch and sucrose. These drugs are sometimes used as diet aids, but neither drug is officially approved as a therapy for weight loss per se.

Three RCTs with metformin from the 1990s were reviewed by the Health Technology Assessment; all three showed modest weight loss at 12 months, and a longer term project (UK Prospective Diabetes Study) demonstrated small losses at 5, 10 and 15 years.[114] In 2002, some evidence for weight reduction was demonstrated for both metformin and acarbose used in patients at risk for developing diabetes.[115],[116] The 2002 acarbose study was the only one included by the Health Technology Assessment (HTA) program. Neither drug made it into the Cochrane review, and the conclusion of HTA is that both were relatively ineffective for weight loss therapy.

Surgical Treatment

Bariatric surgery[117] is considered an intervention of last resort with morbid obesity, where patients have attempted other forms of medical management. Morbid or severe obesity is usually defined as a BMI of 40 or more, or 35 or more with serious comorbidities.[118] Approximately 3% of Canadian and US adults are morbidly obese, with the rate in the UK being somewhat lower.[119],[120]

The main surgical procedures for morbid obesity resistant to other therapies include biliopancreatic diversion[121], gastric bypass[122], gastroplasty[123], and gastric banding[124], though many variations exist.[125] Jejunoileal bypass[126] is an older procedure no longer recommended in the US or

Europe due to poor safety. The aim with each procedure is to restrict intake and /or malabsorption of food, with, it is hoped, a consequent modification of eating behaviour, i.e., smaller quantities of food consumed more slowly.[127] All such surgeries are considered major interventions with risks of significant morbidity and perioperative mortality. Techniques such as vertical banded gastroplasty[128], which can be done laparoscopically (i.e., small incisions and camera-guided), demonstrate fewer complications than open surgery and a shorter recovery period.[129] Whatever the side effects, they are generally thought to be outweighed by the benefits.[130]

A recent Canadian study followed two cohorts of morbidly obese patients for a maximum of 5 years; the treatment group (n=1,035) underwent bariatric surgery, whereas the age- and gender-matched control group (n=5,746) were not surgically managed. The initial excess weight loss with surgery was 67% (no weight loss data was reported for the control group).[131]

A UK review from 1997 concluded that all types of surgical interventions, and especially gastric bypass and vertical banded gastroplasty, were effective (though the included studies were rated poor in quality).[132] The effectiveness of bariatric surgery for weight loss and other health benefits was confirmed over 10-year follow-up in a 2004 controlled study in Sweden.[133]

The 18 studies included in the most recent Cochrane review mostly compared different surgical procedures. [134] Ordered by decreasing weight loss effect, the surgeries would currently be evaluated as follows: gastric bypass>gastric banding>vertical banded gastroplasty>horizontal banded gastroplasty. These results were confirmed by the NICE review mentioned above, as well as by the extensive Health Technology Assessment review of 2002.[135] In all cases the superiority of gastric bypass for weight loss was noted, along with the fact that it is a technically demanding operation.

Based on the limited evidence, the comparative safety and effectiveness of different surgical procedures remains uncertain. As a comparison, a 2004 meta-analysis of a much wider range of studies yielded somewhat different results for the comparative effectiveness of procedures, as measured by the percentage of excess weight loss:[136]

Type of surgery	% excess weight loss
Biliopancreatic diversion	70.1
Gastroplasty	68.2
Gastric bypass	61.6
Gastric banding	47.5

The focus of this meta-analysis was primarily the impact of bariatric surgery on co-morbidities. The results showed that diabetes was resolved in 76.8% of patients and hypertension was resolved or improved in 78.5%.

Laparoscopic versus open methods of surgery, when used with the same procedure, showed no difference in weight loss.[137]

Regulatory and Economic Interventions

Nutrition Labelling / ‘Signposting’

The existing regulations for nutrition labels on package foods is already very clear and comprehensive (see 2003 Guide to Food Labelling and Advertising[138]). Labels using a standard format for ingredients and quantities per recognized unit weight have been mandated by the Dietitians of Canada, and companies need to comply by 2007. However, there are advocates who want to see the system extended beyond the current applications.

A major Canadian legislative initiative, Bill C-398, was withdrawn in March, 2004, for further study. In addition to expanded nutrition labelling on meat and processed foods, it would have required fast food chains to post the calorie content next to items on menu boards, and full-service restaurant chains to disclose the saturated fat, trans fat and sodium levels of its meals. One of the responses of the Canadian restaurant industry was to point out that voluntary nutritional changes were already happening, e.g., low fat and low-carbohydrate menu options, the elimination of trans fats in some settings, and promotions focusing on healthy lifestyles.[139]

In nutritional signposting, food manufacturers whose products meet defined nutritional criteria are allowed to display a logo on the product. In New Zealand, a signposting campaign in concert with the food industry to reduce the amount of salt saw substantial reductions of salt in breads, breakfast cereals and margarine.[140]

The main caution with signposting is the confusion that can result if every food company or store creates their own system; legislation to create consistent criteria and symbols would be prudent.

Food Regulation

Trans fat, a by-product of fat hydrogenation, is found in 40,000 food products. Used for over 75 years, it has recently been shown to increase the risk of heart disease.

On November 23, 2004, the Canadian Parliament voted to set up a task force to recommend ways to reduce trans fats “to the lowest possible levels.”[141] Although exploring such approaches is on the agenda of other countries, so far only Denmark has banned partially hydrogenated oil in its food supply (in 2003). The fast food industry in that country has adapted to the new regulations.

By 2005, Canada will have the most stringent nutrition label requirements in the world.[142] Health Canada estimates that the new labels could save over $5 billion in direct and indirect costs over 20 years. The food industry suggests that the fact that trans fat levels will appear on all processed food products should be sufficient government intervention to protect consumer health.

Taxation and Other Economic Levers

Fats contain approximately double the amount of calories per gram than carbohydrates or protein, making them a highly dense form of energy. Certain animal or saturated fats may be more harmful than those derived from plants

and fish. So, apart from the direct health impact of consuming fats that elevate serum cholesterol levels (e.g., saturated fats, trans fats), excessive intake of all forms of energy-dense fat may be a problem in terms of creating overweight. One suggested regulatory response to this scenario has been to tax high-fat foods in a targeted manner similar to tobacco taxation. In 2003, the British Medical Association recommended a 17.5% value-added tax on fatty foods; an earlier estimate suggested that such a policy could save up to 1,000 premature deaths a year in the UK.[143] Similar taxes have been proposed for foods that are high in sugar.[144] Perhaps the most likely proposal in B.C. is a tax imposed on soft drinks and other snack foods, similar to that already seen in the past in several US states (though two-thirds of them repealed the tax in the 1990s).[145] This coincides with the double reality that evaluating high-fat foods is a complex undertaking, and that the real culprits in obesity (and other aspects of poor health) is energy-dense, nutrient-lacking food sources. As the BC Nutrition Survey of 1999 confirmed, 30% of the province’s energy intake comes from outside the four recommended food groups, i.e., from foods such as donuts, alcohol and candy.[146]

Directing consumers towards low-fat foods using price controls also may not automatically reduce the obesity problem. A 2003 study noted that when people chose low-fat foods they tended to eat larger portion sizes so that almost the same amount of energy was consumed compared to those opting for high-fat foods.[147]

Review articles have suggested a more complex relationship between portion size and energy density, possibly even a moderating effect linked to the order in which food types are consumed.[148]

Although much more research is needed, some studies have shown that combining advice to eat more vegetables and fruit with advice to eat less fat is an effective intervention for weight management.[149] From a regulatory point of view, it would be potentially effective to extend what is known from smaller scale settings such as school cafeterias to the macro-level, i.e., subsidize fruits and vegetables or otherwise lower their cost in order to stimulate purchase rates. This “eat more” strategy has the additional advantage of reflecting a positive behavioural message, similar to “exercise more,” which may be more psychologically palatable and powerful than prohibitions, i.e., “eat less fat and sugar.”

A different economic approach than taxation is to provide individual families with the means to purchase better food. As the Dietitians of Canada report The Cost of Eating in BC notes: “Those living on income assistance are three times more likely to report food insecurity.”[150] Given the strong link between lower socioeconomic status and both poor diet and obesity, policies that address inadequate incomes could contribute to more healthy living, including weight management.[151]

[1] Nyren O. On the long and winding road to an evidence-based diet Acta Oncologica 2003; 42(4): 260-2.

[2] Data summarized at http://www.statcan.ca/Daily/English/040526/d040526e.htm and http://www.statcan.ca/Daily/English/041014/d041014d.htm (accessed November 2004).

[3] Rousseau E. Meeting nutritional needs during adolescence Pro-Teen 2000; 9(1&2): 31-49. Available at www.acsa-caah.ca/pdf/ang/pt091.pdf (accessed December 2004).

[4] Data summarized at http://www.hc-sc.gc.ca/hpfb-dgpsa/onpp-bppn/review_food_supply_e.html (accessed November 2004).

[5] Trends in the Health of Canadian Youth. Available at http://www.hc-sc.gc.ca/english/media /releases/1999/99118ebk3.htm (accessed February 2005).

[6] BC Ministry of Health Services, 2004. Forster-Coull L, Barr SI, Levy-Milne R. British Columbia Nutrition Survey: Report on Food Group Use.

[7] Foerster SB, Kizer KW, Disogra LK et al. California's "5 a day--for better health!" campaign: an innovative population-based effort to effect large-scale dietary change American Journal of Preventive Medicine1995; 11(2): 124-31.

[8] Alcalay R, Bell RA. Promoting Nutrition and Physical Activity through Social Marketing: Current

Practices and Recommendations. Center for Advanced Studies in Nutrition and Social Marketing, University of California, Davis, CA, 2000.

[9] Reger B, Wootan MG, Booth-Butterfield S. Using mass media to promote healthy eating: A community-based demonstration project Preventive Medicine 1999; 29(5): 414-21.

[10] Lin CT, Lee JY, Yen ST. Do dietary intakes affect search for nutrient information on food labels?

[11] Reger B, Wootan MG, Booth-Butterfield S. A comparison of different approaches to promote community-wide dietary change American Journal of Preventive Medicine 2000; 18(4): 271-5.

[12] Pietinen P, Lahti-Koski M, Vartiainen E et al. Nutrition and cardiovascular disease in Finland since the early 1970s: a success story Journal of Nutrition, Health & Aging. 2001; 5(3): 150-4.

[13] Fraser GE. A search for truth in dietary epidemiology American Journal of Clinical Nutrition 2003; 78(suppl): S521-5.

[14] For example, Dixon H, Borland R, Segan C et al. Public reaction to Victoria's "2 Fruit 'n' 5 Veg Every Day" campaign and reported consumption of fruit and vegetables Preventive Medicine 1998; 27(4): 572-82.

[16] Stables GJ, Subar AF, Patterson BH et al. Changes in vegetable and fruit consumption and awareness among US adults: results of the 1991 and 1997 5 A Day for Better Health Program surveys Journal of the American Dietetic Association 2002; 102(6): 809-17. For an international comparison: Ashfield-Watt PA, Stewart E, Scheffer J. 5+ a day: Are we getting the message across? Asia Pacific Journal of Clinical Nutrition 2004; 13 (Suppl): S38.

[17] Stables GJ, Subar AF, Patterson BH et al. Changes in vegetable and fruit consumption and awareness among US adults: results of the 1991 and 1997 5 A Day for Better Health Program surveys Journal of the American Dietetic Association 2002; 102(6): 809-17.

[18] Serdula MK, Gillespie C, Kettel-Khan L et al. Trends in fruit and vegetable consumption among adults in the United States: Behavioral Risk Factor Surveillance System, 1994–2000 American Journal of Public Health 2004; 94(6): 1014-8.

[19] Rickersten K. The effects of advertising in an inverse demand system: Norwegian vegetables revisited European Review of Agricultural Economics 1998; 25(1): 129-40.

[20] Lutz SF, Ammerman AS, Atwood JR et al. Innovative newsletter interventions improve fruit and vegetable consumption in healthy adults Journal of the American Dietetic Association 1999; 99(6): 705-9.

[21] Kristal AR, Goldenhar L, Muldoon J et al. Evaluation of a supermarket intervention to increase consumption of fruits and vegetables American Journal of Health Promotion 1997; 11(6): 422-5.

[22] Anderson ES, Winett RA, Wojcik JR et al. A computerized social cognitive intervention for nutrition behavior: direct and mediated effects on fat, fiber, fruits, and vegetables, self-efficacy, and outcome expectations among food shoppers Annals of Behavioral Medicine 2001; 23(2): 88-100.

[23] Snyder LB, Hamilton MA, Mitchell EW et al. A meta-analysis of the effect of mediated health communication campaigns on behavior change in the United States Journal of Health Communication. 2004; 9(Suppl 1): 71-96.

[24] Roe L, Hunt P, Bradshaw H et al. Health Promotion Interventions to Promote Healthy Eating in the General Population: A Review. London: Health Education Authority, 1997.

[25] For example, Campbell MK, Demark-Wahnefried W, Symons M et al. Fruit and vegetable consumption and prevention of cancer: the Black Churches United for Better Health project American Journal of Public Health 1999; 89(9): 1390-6.

[26] Glanz K, Yaroch AL. Stratrgies for increasing fruit and vegetable intake in grocery stores and communities: policy, pricing, and environmental change Preventive Medicine 2004; 39: S75-80.

[27] Roe L, Hunt P, Bradshaw H et al. Health Promotion Interventions to Promote Healthy Eating in the General Population: A Review. London: Health Education Authority, 1997.

[28] Schwab M, Syme SL. On paradigms, community participation, and the future of public health American Journal of Public Health 1997; 87(12): 2049-50.

[29] Roe L, Hunt P, Bradshaw H et al. Health Promotion Interventions to Promote Healthy Eating in the General Population: A Review. London: Health Education Authority, 1997.

[30] Glanz K, Hoelscher D. Increasing fruit and vegetable intake by changing environments, policy and pricing: restaurant-based research, strategies, and recommendations Preventive Medicine 2004; 39: S88-93.

[31] Young LR, Nestle M. The contribution of expanding portion sizes to the US obesity epidemic American Journal of Public Health 2002; 92(2): 246-9.

[32] Cassady D, Housemann R, Dagher C. Measuring cues for healthy choices on restaurant menus: development and testing of a measurement instrument American Journal of Health Promotion 2004; 18(6): 444-9.

[33] Glanz K, Hoelscher D. Increasing fruit and vegetable intake by changing environments, policy and pricing: restaurant-based research, strategies, and recommendations Preventive Medicine 2004; 39: S88-93.

[34] Fitzgerald CM, Kannan S, Sheldon S et al. Effect of a promotional campaign on heart-healthy menu choices in community restaurants Journal of the American Dietetic Association 2004; 104(3): 429-32.

[35] Glanz K, Yaroch AL. Stratrgies for increasing fruit and vegetable intake in grocery stores and communities: policy, pricing, and environmental change Preventive Medicine 2004; 39: S75-80.

[36] Seymour JD, Yaroch AL, Serdula M et al. Impact of nutrition environmental interventions on point-of-purchase behaviour in adults: a review Preventive Medicine 2004; 39: S108-36.

[37] Block JP, Scribner RA, DeSalvo KB. Fast food, race/ethnicity, and income: a geographic analysis American Journal of Preventive Medicine 2004; 27(3): 211-7.

[38] Pereira MA, Kartashov AI, Ebbeling CB et al. Fast-food habits, weight gain, and insulin resistance (the CARDIA study): 15-year prospective analysis. The Lancet. 2005; 365(9453):36-42.

[39] Levitsky DA, Youn T. The more food young adults are served, the more they overeat Journal of Nutrition 2004; 134(10): 2546-9.

[40] Ludwig DS, Pereira MA, Kroenke CH et al. Dietary fiber, weight gain, and cardiovascular disease risk factors in young adults. Journal of the American Medical Association.1999; 282(16):1539-46.

[41] Pereira MA, Ludwig DS. Dietary fiber and body-weight regulation. Observations and mechanisms.

[42] Heald AH, Golding C, Sharma R et al. A substitution model of dietary manipulation is an effective means of optimising lipid profile, reducing C-reactive protein and increasing insulin-like growth factor-1. British Journal of Nutrition. 2004; 92(5):809-18.

[43] Kirkpatrick S, Tarasuk V. The relationship between low income and household food expenditure patterns in Canada Public Health Nutrition 2003; 6(6): 589-97.

[44] Krebs-Smith SM, Kantor LS. Choose a variety of fruits and vegetables daily: understanding the complexities Journal of Nutrition 2001; 131(2S-1): S487-501.

[45] Sloane DC, Diamant AL, Lewis LB et al. Improving the nutritional resource environment for healthy living through community-based participatory research Journal of General Internal Medicine 2003; 18(7): 568-75.

[46] Rose D, Richards R. Food stores access and household fruit and vegetable use among participants in the US Food Stamp Program Public Health Nutrition 2004; 7(8): 1081-8.

[47] Glanz K, Yaroch AL. Strategies for increasing fruit and vegetable intake in grocery stores and communities: policy, pricing, and environmental change Preventive Medicine 2004; 39: S75-80.

[48] CBC News. Grocery wins diabetes prevention award, December 20, 2004 available at http://www.cbc.ca/story/science/national/2004/12/20/diabetes-prevent041220.html?print (accessed December 2004).

[49] Drewnowski A, Darmon N, Briend A. Replacing fats and sweets with vegetables and fruits—a question of cost American Journal of Public Health 2004; 94(9): 1555-9.

[50] Truby H, Millward D, Morgan L et al. A randomized controlled trial of 4 different commercial weight loss programmes in the UK in obese adults: body composition changes over 6 months Asia Pacific Journal of Clinical Nutrition 2004; 13(Suppl): S146.

[51] Tsai AG, Wadden TA. Systematic review: an evaluation of major commercial weight loss programs in the United States. Annals of Internal Medicine. 2005; 142:56-66.

[52] Heshka S, Anderson JW, Atkinson RL et al. Weight loss with self-help compared with a structured commercial program: a randomized trial. Journal of the American Medical Association.2003; 289(14):1792-8.

[53] Roe L, Hunt P, Bradshaw H et al. Health Promotion Interventions to Promote Healthy Eating in the General Population: A Review. London: Health Education Authority, 1997.

[54] National Public Health Partnership. An Intervention Portfolio to Promote Fruit and Vegetable Consumption. 2000. Available at http://www.nphp.gov.au/publications/signal/intfv1.pdf (accessed November 2004).

[55] Glanz K, Mullis R. Environmental interventions to promote healthy eating: a review of models, programs, and evidence Health Education Quarterly1988; 15: 395–415.

[56] Glanz K, Lankenau B, Foerster S et al. Environmental and policy approaches to cardiovascular disease prevention through nutrition: opportunities for state and local action Health Education Quarterly 1995; 22: 512–27.

[57] Wechsler H, Devereaux RS, Davis M et al. Using the school environment to promote physical activity and healthy eating Preventive Medicine 2000; 31: S121–37.

[58] French SA, Story M, Jeffery RW. Environmental influences on eating and physical activity Annual Review of Public Health. 2001; 22: 309-35.

[59] French SA, Stables G. Environmental interventions to promote vegetable and fruit consumption among youth in school settings Preventive Medicine 2003; 37(6 Pt 1): 593-610.

[60] Roe L, Hunt P, Bradshaw H et al. Health Promotion Interventions to Promote Healthy Eating in the General Population: A Review. London: Health Education Authority, 1997.

[61] Seymour JD, Yaroch AL, Serdula M et al. Impact of nutrition environmental interventions on point-of-purchase behaviour in adults: a review Preventive Medicine 2004; 39: S108-36.

[62] National Public Health Partnership. An Intervention Portfolio to Promote Fruit and Vegetable Consumption. 2000. Available at http://www.nphp.gov.au/publications/signal/intfv1.pdf (accessed November 2004).

[63] Perry CL, Bishop DB, Taylor G et al. Changing fruit and vegetable consumption among children: the 5-a-Day Power Plus program in St. Paul, Minnesota American Journal of Public Health 1998; 88(4): 603-9.

[64] National Public Health Partnership. An Intervention Portfolio to Promote Fruit and Vegetable Consumption. 2000. Available at http://www.nphp.gov.au/publications/signal/intfv1.pdf (accessed November 2004).

[65] Lowe CF, Horne PJ, Tapper K et al. Effects of a peer modelling and rewards-based intervention to increase fruit and vegetable consumption in children European Journal of Clinical Nutrition 2004; 58(3): 510-22.

[66] French SA, Story M, Jeffery RW et al. Pricing strategy to promote fruit and vegetable purchase in high school cafeterias Journal of the American Dietetic Association 1997; 97(9): 1008-10.

[67] French SA, Stables G. Environmental interventions to promote vegetable and fruit consumption among youth in school settings Preventive Medicine 2003; 37(6 Pt 1): 593-610.

[68] Perry CL, Bishop DB, Taylor GL et al. A randomized school trial of environmental strategies to encourage fruit and vegetable consumption among children Health Education & Behavior 2004; 31(1): 65-76.

[69] Ammerman A, Lindquist C, Hersey J et al. Efficacy of interventions to modify dietary behavior related to cancer risk. Evidence Report/Technology Assessment No. 25: AHRQ, 2001.

[70] See, for example, Berenbaun S. Nutrition in Saskatchewan Schools: Policy, Practice and Needs. 2004. Available at http://ww1.heartandstroke.sk.ca/Images/English/SK-Nutrition-Report-April-2004.pdf (accessed November 2004).

[71] French SA, Story M, Fulkerson JA, Gerlach AF. Food environment in secondary schools: a la carte, vending machines, and food policies and practices American Journal of Public Health 2003; 93(7): 1161-7.

[72] Kendall PRW. An Ounce of Prevention: A Public Health Rationale for the School as a Setting for Health Promotion, 2003.

[73] Ludwig DS, Peterson KE, Gortmaker SL. Relation between consumption of sugar-sweetened drinks and childhood obesity: a prospective, observational analysis. The Lancet. 2001; 357:505-8.

[74] French SA, Hannan PJ, Story M. School soft drink intervention study British Medical Journal 2004; 329(7462): E315-6.

[75] Field AE, Austin SB, Gillman MW et al. Snack food intake does not predict weight change among children and adolescents. International Journal of Obesity & Related Metabolic Disorders. 2004; 28(10):1210-6.

[76] News stories at http://www.bcctv.ca/displayresults.jsp?id=/news/stories/2004/11/news-20041107-06.htm and http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/1096472213533_91881413? hub=Health (accessed November 2004) and http://www.torontofreepress.com/2004/weinreb102604.htm (accessed February 2005).

[77] Hannan P, French SA, Story M et al. A pricing strategy to promote sales of lower fat foods in high school cafeterias: acceptability and sensitivity analysis American Journal of Health Promotion 2002; 17(1): 1-6.

[78] French SA, Wechsler H. School-based research and initiatives: fruit and vegetable environment, policy, and pricing workshop Preventive Medicine 2004; 39: S101-7.

[79] French SA, Jeffery RW, Story M et al. Pricing and promotion effects on low-fat vending snack purchases: the CHIPS Study American Journal of Public Health 2001; 91(1): 112-7.

[80] French SA. Story M. Jeffery RW et al. Pricing strategy to promote fruit and vegetable purchase in high school cafeterias Journal of the American Dietetic Association 1997; 97(9): 1008-10.

[81] Fiske A, Cullen KW. Effects of promotional materials on vending sales of low-fat items in teachers' lounges Journal of the American Dietetic Association 2004; 104(1) :90-3.

[82] Horgen KB, Brownell KD. Comparison of price change and health message interventions in promoting healthy food choices. Health Psychology. 2002; 21(5):505-12.

[83] Cousins JH, Rubovits DS, Dunn JK et al. Family versus individually oriented intervention for weight loss in Mexican American women Public Health Reports 1992; 107(5): 549-55.

[84] Wing RR, Jeffery RW. Benefits of recruiting participants with friends and increasing social support for weight loss and maintenance Journal of Consulting & Clinical Psychology 1999; 67(1): 132-8.

[85] Avenell A, Broom J, Brown TJ et al. Systematic review of the long-term effects and economic consequences of treatments for obesity and implications for health improvement Health Technology Assessment 2004; 8(21).

[86] Dietz WH, Gortmaker SL. Preventing obesity in children and adolescents Annual Review of Public Health 2001; 22: 337-53.

[87] Glenny AM, O’Meara, Melville A et al. The treatment and prevention of obesity: a systematic review of the literature International Journal of Obesity 1997; 21(9): 715-37.

[88] Source: http://www.asso.org.au//freestyler/gui/files/healthy_weight_2008.pdf (accessed December 2004).

[89] Armitage CJ, Conner M. Efficacy of a minimal intervention to reduce fat intake Social Science & Medicine 2001; 52(10): 1517-24.

[90] Thomas RJ, Kottke TE, Brekke MJ et al. Attempts at changing dietary and exercise habits to reduce risk of cardiovascular disease: who's doing what in the community? Preventive Cardiology 2002; 5(3): 102-8.

[91] Liao KL. Cognitive-behavioural approaches and weight management: an overview Journal of the Royal Society of Health 2000; 120(1): 27-30.

[92] Shaw K, Kenardy J, O'Rourke P et al. Psychological interventions for obesity Cochrane Metabolic and Endocrine Disorders Group Cochrane Database of Systematic Reviews, 2003.

[93] Wilson GT. Cognitive behavior therapy for eating disorders: progress and problems Behaviour Research & Therapy 1999; 37(Suppl 1): S79-95.

[94] Cooper Z, Fairburn CG. A new cognitive behavioural approach to the treatment of obesity Behaviour Research & Therapy 2001; 39(5):499-511.

[95] Shaw K, Kenardy J, O'Rourke P et al. Psychological interventions for obesity Cochrane Metabolic and Endocrine Disorders Group Cochrane Database of Systematic Reviews, 2003.

[96] Hayaki J, Brownell KD. Behaviour change in practice: group approaches International Journal of Obesity & Related Metabolic Disorders 1996; 20(Suppl 1): S27-30.

[97] Pignone MP, Ammerman A, Fernandez L et al. Counseling to promote a healthy diet in adults: a summary of the evidence for the U.S. Preventive Services Task Force American Journal of Preventive Medicine 2003; 24(1): 75-92.

[98] Avenell A, Broom J, Brown TJ et al. Systematic review of the long-term effects and economic consequences of treatments for obesity and implications for health improvement Health Technology Assessment 2004; 8(21).

[99] Dunshea-Mooij CAE, Ni Mhurchu C, Bennett D et al. Chitosan for overweight or obesity Cochrane Database of Systematic Reviews, 2003.

[100] Pirozzo S, Summerbell C, Cameron C et al. Advice on low-fat diets for obesity Cochrane Database of Systematic Reviews, 2004.

[101] Avenell A, Broom J, Brown TJ et al. Systematic review of the long-term effects and economic consequences of treatments for obesity and implications for health improvement Health Technology Assessment 2004; 8(21).

[102] Stenius-Aarniala B, Poussa T, Kvarnstrom J et al. Immediate and long term effects of weight reduction in obese people with asthma: randomised controlled study British Medical Journal 2000; 320(7238): 827-32.

[103] For example, Miyashita Y, Koide N, Ohtsuka M et al. Beneficial effect of low carbohydrate in low calorie diets on visceral fat reduction in type 2 diabetic patients with obesity Diabetes Research & Clinical Practice 2004; 65(3): 235-241.

[104] Padwal R, Li SK, Lau DCW. Long-term pharmacotherapy for obesity and overweight Cochrane Metabolic and Endocrine Disorders Group Cochrane Database of Systematic Reviews, 2004.

[105] Hutton B, Fergusson D. Changes in body weight and serum lipid profile in obese patients treated with orlistat in addition to a hypocaloric diet: a systematic review of randomized clinical trials
American Journal of Clinical Nutrition. 2004; 80(6):1461-1468.

[106] O'Meara S, Riemsma R, Shirran L et al. A rapid and systematic review of the clinical effectiveness and cost effectiveness of orlistat in the management of obesity Health Technology Assessment 2001; 5(18).

[107] O'Meara S, Riemsma R, Shirran L et al. The clinical effectiveness and cost effectiveness of sibutramine in the management of obesity: a technology assessment Health Technology Assessment 2002; 6(6).

[108] Avenell A, Broom J, Brown TJ et al. Systematic review of the long-term effects and economic consequences of treatments for obesity and implications for health improvement Health Technology Assessment 2004; 8(21).

[109] Haddock CK, Poston WSC, Dill PL et al. Pharmacotherapy for obesity: a quantitative analysis of four decades of published randomized clinical trials International Journal of Obesity and Related Metabolic Disorders 2002; 26: 262-73.

[110] Padwal R, Li SK, Lau DCW. Long-term pharmacotherapy for obesity and overweight Cochrane Metabolic and Endocrine Disorders Group Cochrane Database of Systematic Reviews, 2004.

[111] Note that these drugs do not cause weight loss directly, but rather enhance insulin availability.

[112] Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin New England Journal of Medicine 2002; 346: 393-403.

[113] Chiasson JL, Josse RG, Gomis R et al. Acarbose for prevention of type 2 diabetes mellitus: the STOP-NIDDM randomised trial The Lancet 2002; 359: 2072-7.

[114] Avenell A, Broom J, Brown TJ et al. Systematic review of the long-term effects and economic consequences of treatments for obesity and implications for health improvement Health Technology Assessment 2004; 8(21).

[115] Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin New England Journal of Medicine 2002; 346: 393-403.

[116] Chiasson JL, Josse RG, Gomis R et al. Acarbose for prevention of type 2 diabetes mellitus: the STOP-NIDDM randomised trial The Lancet 2002; 359: 2072-7.

[117] Surgery on the stomach and/or intestines to help the patient with extreme obesity lose weight.

[118] National Institute for Clinical Excellence. Guidance on the Use of Surgery to Aid Weight Reduction for People with Morbid Obesity. Technology Appraisal Guidance 46, 2002.

[119] Colquitt J, Clegg A, Sidhu M et al. Surgery for morbid obesity Cochrane Database of Systematic Reviews, 2003.

[120] Trakas K, Oh PI, Singh S et al. The health status of obese individuals in Canada International Journal of Obesity & Related Metabolic Disorders 2001; 25(5): 662-8.

[121] A surgical procedure which diverts pancreatobiliary secretions via the small intestine into the large intestine, the remaining small intestine being grafted to the stomach after removal of half of the stomach.

[124] A gastric band device is introduced into the abdomen and is placed around the upper part of the stomach. The resulting pouch (or the "new stomach") dramatically reduces the functional capacity of the stomach.

[125] Colquitt J, Clegg A, Sidhu M et al. Surgery for morbid obesity Cochrane Database of Systematic Reviews, 2003.

[127] Restrictive surgery, which includes gastroplasty and gastric banding, reduces the size of the stomach so that the patient feels full with less food. Malabsorptive procedures, which include biliopancreatic bypass and gastric bypass, parts of the gastrointestinal tract are surgically bypassed so that absorption of food is limited. National Institute for Clinical Excellence. Guidance on the Use of Surgery to Aid Weight Reduction for People with Morbid Obesity. Technology Appraisal Guidance 46, 2002.

[128] Creation of a small pouch in the upper stomach with a narrow outlet reinforced by a mesh band to prevent stretching. The pouch fills quickly and empties slowly with solid food, producing a feeling of fullness. This restricts food intake.

[129] Colquitt J, Clegg A, Sidhu M et al. Surgery for morbid obesity Cochrane Database of Systematic Reviews, 2003.

[130] National Institute for Clinical Excellence. Guidance on the Use of Surgery to Aid Weight Reduction for People with Morbid Obesity. Technology Appraisal Guidance 46, 2002.

[131] Christou NV, Sampalis JS, Liberman M et al. Surgery decreases long-term mortality, morbidity, and health care use in morbidly obese patients. Annals of Surgery 2004; 240(3): 416-23.

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CANCER PREVENTION INSTITUTE OF CANADA

Nutrition

Community-based Interventions

Workplace-based Interventions

Counselling

Dietary Treatment