Before you respond “of course” – you may wish to take a look at the systematic review by Laura Cobb and colleagues from Johns Hopkins University, published in OBESITY.
The authors looked at 71 Canadian and US studies that examined the relationship between obesity and retail food environments and concluded that,
“Despite the large number of studies, we found limited evidence for associations between local food environments and obesity. “
To be fair, the researchers also concluded that much of the research in this area lacks high-quality studies, that would lead to a more robust understanding of this issue.
In fact, the authors had to slice and dice the data to tease out “positive” findings that included a possible relationship between fast food outlets and obesity in low-income children or an inverse trend for obesity with the availability of supermarkets (a supposed surrogate measure for availability of fresh produce).
Of course, not finding a robust relationship between the food environment and obesity should not be all that surprising, given the many factors that can potentially play a role in obesity rates.
(Readers may recall that there used to be similar enthusiasm between the role of the built environment (e.g. walkability) for rising obesity rates, till the research on this issue turned out to be rather inconclusive. )
None of this should be interpreted to mean that the food or built environments have nothing to do with obesity – however, we must remember that these type of studies virtually never prove causality and that the factors that determine food and built environments are in fact almost as complicated as the factors that determine individual body weights, so finding a robust relationship between the two would be rather surprising.
Allow me to predict that with the increasing trend of fast food outlets offering healthier (or rather less-unhealthy) choices and supermarkets offering ample amounts of “fast food” and a vast array of unhealthy packaged foods, any relationship between retail food environments and obesity (even if it does exist), will be even harder to prove that ever before (outliers are no better than anecdotal evidence and should generally be ignored).
Changing food environments to provide better access to affordable healthier foods should be a “no-brainer” for policy makers, irrespective of whether or not the current environment has anything to do with obesity or not (the same could be said for walkability of neighbourhoods and the prevention of urban sprawl).
Today’s guest post comes from Catherine B. Chan and Rhonda C. Bell, Professors in Human Nutrition at the University of Alberta. It describes their Pure Prairie Eating Plan (PPEP) and how they went about developing this rather unique venture into eating local.
Healthy eating is a key factor in preventing and treating chronic diseases such as heart disease, stroke, cancer and diabetes. According to the World Health Organization, good nutrition is one of 4 key factors that could help postpone or avoid 90% of type 2 diabetes and 80% of coronary heart disease.
The Mediterranean Diet has gained popularity as a healthy diet, but evidence gathered through research on Canadian prairiegrown products (canola, flax, barley, pulses, dairy and meats) demonstrates that many local foods have similar nutritional qualities and would be more acceptable and accessible to people who live in Alberta, Saskatchewan and Manitoba.
Our recent project was conceived to develop, test and demonstrate the potential health benefits of a dietary pattern based on foods that are commonly grown and consumed in a “made in Canada” menu plan.
How the Pure Prairie Eating Plan (PPEP) was developed
The original purpose of the menu plan was to help people with type 2 diabetes adhere to the nutrition recommendations of the Canadian Diabetes Association (CDA) by focusing on healthy food choices with a local flavour. The menu plan concept integrates knowledge gained through research related to consumer behavior, behavior change, and nutritional quality of dairy, meats,
canola, pulses and grains.
During its development, it was recognized that a diet healthy for people with diabetes is a diet healthy for everyone. This notion was reinforced in a Consensus Conference with people living with type 2 diabetes, who felt strongly that their diet should not be different from others.
This approach provided knowledge that formed the basis of a 4-week menu plan focused on foods that are grown and readily available in the Canadian prairies. The plan consists of 28 days of diabetes-friendly menus including 3 meals and 3 snacks each day, approximately 100 recipes, tips for healthy eating, pantry and grocery lists and other helpful information.
If followed consistently, the menus meet the recommendations of Eating Well with Canada’s Food Guide on a daily basis, and over 1 week averages approximately 2000 kcal/day with macronutrient distribution consistent with health recommendations.
The menus also provide total fibre between 25 and 50 g/day. Many of the recipes have been obtained from our provincial agricultural commodity groups (see http://pureprairie.ca/oursponsors/).
The recipe ingredients feature many homegrown foods from each food group. They are quick and easy to make…and tasty!
Our Research Findings
Funding was secured through the Alberta Diabetes Institute to pilot test the menu plan concept in a 12-week intervention that measured both quantitative (disease biomarkers) and qualitative (acceptability, accessibility and acceptability) responses to the menu plan of 15 people with type 2 diabetes.
The results, published in the Canadian Journal of Diabetes, showed that most participants liked the menu plan and their A1c decreased by an average of 1%.
However, many were not used to cooking from scratch and cited time as a barrier to using the menu plan more. The benefits of the menu plan included more structure in participants’ diets, increased frequency of snacking, increased awareness of food choices, purchasing healthier foods and better portion control.
Participants were aware of better blood sugar control. Participants were pleased with the variety of food choices and liked the taste of the recipes. They also liked the flexibility of the menu plan.
In the second phase, which included 73 participants, we included a 5-week curriculum delivered in a smallgroup setting with a facilitator and included assessment of hemoglobin A1c as a measure of blood sugar control as well as cardiovascular risk factors. Nutrient intake was assessed using a computerbased 24-hour recall system called WebSpan.
In this study, 86% of those enrolled completed all aspects of the programme, including the 3-month followup. On average, there were decreases in A1c (0.7%), body mass index (0.6 kg/m2) and waist circumference (2 cm). (Note that a decrease in A1c of 0.5% is considered to be a clinically relevant improvement in blood sugar control.)
Although the weight loss was relatively small, it correlated with the reduction in A1c more strongly than any other factor examined.
Analysis of nutrient intakes showed decreases in total energy intake (127 kcal/day), total fat (7 g), total sugar (25 g) and sodium (469 mg).
The Pure Prairie Eating Plan (PPEP)
With promising outcomes regarding the nutritional adequacy and acceptability of the menu plan, and with encouragement from Alberta agricultural commodity groups and others, we packaged and rebranded the menu plan as the Pure Prairie Eating Plan (PPEP): Fresh Food, Practical Menus and a Healthy Lifestyle.
PPEP is available for purchase in selected bookstores throughout the prairies and proceeds from its sale will be used to further research into improving the lifestyle behaviours of Canadians with or at risk of chronic diseases.
For a listing of bookstores currently stocking PPEP, or to buy online, click here
Healthcare providers wishing to purchase 6 copies or more can contact firstname.lastname@example.org for a discount.
We would like to acknowledge the financial support of our sponsors.
Dr. Catherine Chan is Professor of Human Nutrition and Physiology at the University of Alberta. Her research (Physical Activity and Nutrition for Diabetes in Alberta, PANDA) focuses on the development, implementation and evaluation of healthy behavior interventions as well as on identification and testing of healthy food ingredients. She is also the Scientific Director for the
Diabetes, Obesity and Nutrition Strategic Clinical Network of Alberta Health Services.
Dr. Rhonda Bell is Professor of Human Nutrition and leader of the ENRICH project (Promoting Appropriate Maternal Body Weight in Pregnancy and Postpartum through Health Eating) at the University of Alberta. The ENRICH project aims to develop and promote practical strategies for women to maintain healthier weights during and following pregnancy.
As regular readers are well aware, obesity is a chronic disease which simply means that any treatment you decide to pursue needs to be one you can stick with in the long-term (this applies as much to your diet as it does to taking an anti-obesity drug or, for that matter having surgery – when the treatment stops the weight comes back!).
That said, it would be easy to assume that if you chose (or otherwise have a say) in the kind of diet you think will help you manage your weight, you’d a) lose more weight and b) be more likely to keep it off.
As a randomised controlled study by Annals of Internal Medicine, neither of these assumptions may be true.Duke University Medical Center, Durham, North Carolina, published in the
The researchers randomised 207 participants to two groups – a choice group in which participants had the choice of going either on a low-carbohydrate (less than 20 g/day) or low-fat diet (less than 30% energy from fat).
The non-choice group was not given this choice but were randomly assigned to either of these diets. Both groups were provided with group and telephone counseling for 48 weeks.
Of the 105 choice participants, 58% chose low-carb and 44% chose low-fat – 83% completed the study – and lost on average 5.7Kg.
Of the 102 non-choice participants, 52 % were assigned to low-carb and 48% to low-fat – 86% completed the study – and lost on average 6.7 Kg.
Of note, the actual reported intake of carb in the low-carb groups ranged between 45-80 g of carbs per day (down from about 200 g/day) while fat intake in this group increased from about 40 to 55% of total energy); In the low-fat group, actual fat intake, fell from about 40% at baseline to about 35% on the diet.
There were no difference in dietary adherence, physical activity or quality of life.
This study illustrates that whether or not you get to chose your preferred diet or not doesn’t matter – what does is that you stick with it.
Or as the authors put it,
“The double-randomized preference design of our study allowed us to determine that preference did not meaningfully affect weight loss. Moreover, the range of estimated weight differences between groups in the 95% CIs does not contain a clinically meaningful difference in favor of the choice group.”
Both findings may not be exactly what one may have predicted – which is exactly why we need these types of studies.
It turns out that we have a rather sophisticated sensing mechanism in our gut that senses the composition of our diet and interacts with the brain to regulate our appetite and food intake.
Just how exactly this gut “nutrient-sensing” system works, is reviewed by Sophie Hamr and colleagues from the University of Toronto in a paper published in Current Diabetes Reports.
As the authors point out,
“…the gastrointestinal (GI) tract is anatomically positioned to provide initial feedback following a meal via detection of incoming nutrients and relaying signals to the brain and peripheral tissues to prevent excess energy intake and circulating nutrients…..This, coupled with the vast neural and humoral connectivity of the gut to other important sites of energy regulation, such as the brain, allows the gut to effectively relay information to the rest of the body about the size and composition of an incoming meal.”
Each nutrient (fats, carbohydrates, protein) interacts with specific sensory and signal transduction mechanisms in the gut.
Animal studies show that exposing the gut to certain nutrients (for e.g. by tube feeding) can stimulate or suppress feeding behaviour making animals chose or avoid certain foods. Often these effects can persist for days or even weeks, well beyond the time course of a single meal.
Furthermore, these effects appear to be largely dependent on the presence of specific nutrients rather than on the actual nutritional or energy state of the animal.
“…these evidences lend notion for the intestine to sense specific nutrients (i.e., lipid and carbohydrate) at specific concentrations, rather than calories, in an effort to drive further food consumption.”
The authors point out that changes in how the gut senses nutrients may well explain how bariatric surgery works to reduce appetite and change food preferences.
No doubt, a better understanding these mechanisms and the molecular mechanisms involved could lead to novel dietary or pharmacological interventions to prevent or treat obesity.
If you are planning to attend the 4th Canadian Obesity Summit in Toronto next week (and anyone else, who is interested), you can now download the program app on your mobile, tablet, laptop, desktop, eReader, or anywhere else – the app works on all major platforms and operating systems, even works offline.
You can access and download the app here.
(To watch a brief video on how to install this app on your device click here)
You can then create an individual profile (including photo) and a personalised day-by-day schedule.
Obviously, you can also search by speakers, topics, categories, and other criteria.
Hoping to see you at the Summit next week – have a great weekend!