While at the level of the individual, clinicians are beginning to acknowledge the vast body of research now showing that “lifestyle” approaches to managing obesity (“eat-less move more”) result in minimal outcomes (3-5% sustainable weight loss at best), public health attempts to address the obesity epidemic continue to perpetuate the myth that obesity (and its prevention) is simply about getting people to eat better and move more (with very little evidence to show that such measures can be implemented at a population level to effect any noticeable change in obesity rates).
In an article I co-authored with Ximena Ramos-Salas, published in Current Obesity Reports, we provide an in-depth overview of current public health policies to address obesity in Canada and argue that the “narrative” underlying these policies is an important driver of weight-bias and discrimination and significantly hindering efforts to provide Canadians living with obesity better access to obesity prevention and treatment efforts.
As we state in the article (based on original research by Ramos-Salas and others),
“A critical review of Canadian obesity prevention policies and strategies revealed five prevailing narratives about obesity: “(1) childhood obesity threatens the health of future generations and must be prevented; (2) obesity can be prevented through healthy eating and physical activity; (3) obesity is an individual behavior problem; (4) achieving a healthy body weight should be a population health target; and (5) obesity is a risk factor for other chronic diseases not a disease in itself”. These narratives create the opportunity for Canadian obesity policy recommendations to focus mainly on individual-based healthy eating and physical activity interventions. By simplifying the causes of obesity as unhealthy eating and lack of physical activity, these policies may be contributing to the belief that obesity can be solely controlled through individual behaviors. This belief is a fundamental driver of weight bias.”
This “world-view” of obesity at the level of policy makers has a significant impact on the willingness and capacity of health systems to provide access to evidence-based obesity treatments to the nearly 7 million Canadian adults and children living with this chronic disease – in fact, the unwillingness to even consider obesity a chronic disease is a big part of the problem.
“..the conceptualization of obesity as a risk factor in public health policies has implications for government action, by prioritizing prevention over treatment strategies and potentially alienating Canadians who already have obesity. The review concludes that existing Canadian public health policies and strategies (a) are not sufficiently comprehensive (i.e., solely focused on prevention and mainly focused on children; exclude evidence-based management approaches; are not person-centered); (b) are based on reductionist obesity models (i.e., models that cast shame and blame on individuals by focusing on individuals’ responsibility for their weight); and (c) do not account for individual heterogeneity in body size and weight (i.e., generalize weight and health outcomes at the population level).”
In contrast we suggest that,
“Adopting a chronic disease framework for obesity would imply that both prevention and management strategies need to be implemented. Within this chronic disease context, public health should ensure that strategies do not have unintended consequences for individuals and populations, such as perpetuating weight bias. There is now sufficient evidence demonstrating that weight bias and obesity stigma are fundamental drivers of health inequalities. Public health has an opportunity to leverage existing health promotion frameworks such as the health for all policy framework and the global plan of action on social determinants of health to address weight bias and obesity stigma”.
Based on the analyses presented in this paper, we make the following recommendations:
Canadian provincial and territorial governments, employers, and the health insurance industry should officially adopt the position of the Canadian Medical Association and the World Health Organization that obesity is a chronic disease and orient their approach/resources accordingly.
Canadian provincial and territorial governments should recognize that weight bias and obesity stigma are significant barriers to helping people with obesity and enshrine rights in provincial/territorial human rights codes, workplace regulations, healthcare systems, and education policies.
In an era of people-centered health care, public health and health system decision makers should engage people with obesity in the development of policies and strategies. Having active participation of individuals with obesity can help change negative attitudes and beliefs about obesity and facilitate the development of compassionate and equitable health promotion strategies.
Employers should recognize and treat obesity as a chronic disease and provide coverage for evidence-based obesity treatments for their employees through health benefit plans.
Provincial and territorial governments should increase training for health professionals on obesity prevention and management.
Existing Canadian Clinical Practice Guidelines for the management and treatment of obesity in adults should be updated to reflect advances in obesity management and treatment in order to support the development of evidence-based programs and strategies by health systems, employers and health insurance companies.
In the same manner in that there is not one predisposing factor for the development of obesity, the phenotypic clinical presentation of obesity is likewise extraordinarily heterogenous. (This has some authors speaking of “obesities” rather than “obesity”).
While it is now well established that BMI is a measure of size rather than health, it is perhaps less well recognised how the different types of body fat and their storage in various fat depots and organs can contribute to cardiometabolic disease (location, location, location!).
Now, a comprehensive review by Ian Neeland from the University of Texas Southwestern Medical Center, Dallas, together with my colleagues Paul Poirier and JP Despres from Laval University in Quebec, published in Circulation discusses the cardiovascular and metabolic heterogeneity of obesity.
As the authors point out,
“Although the BMI has been a convenient and simple index to monitor the growth in obesity prevalence at the population level, many metabolic and clinical studies have revealed that obesity, when defined on the basis of the BMI alone, is a remarkably heterogeneous condition. For instance, patients with similar body weight or BMI values have been shown to display markedly different comorbidities and levels of health risk.”
Not only has BMI never emerged as a significant component in risk engines such as the Framingham risk score, there are many individuals with obesity who never develop metabolic complications or heart disease during the course of their life.
The paper offers a good review of what the author describe as adipose dysfunction or “adiposopathy” = “sick fat”. Thus, in some individuals, there is an accumulation of “unhealthy” fat (particularly visceral and ectopic fat), whereas in others, excess fat predominantly consists of “healthy” fat (predominantly in subcutaneous depots such as the hips and thighs).
The authors thus emphasise the importance of measuring fat location with methods ranging from simple anthropometric measures (e.g. waist circumference) to comprehensive imaging techniques (e.g. MRI).
The authors also provide a succinct overview of exactly how this “sick fat” contributes to cardiometabolic risk and briefly touches on the behavioural, medical, and surgical management of patients with obesity and elevated cardiometabolic risk.
I, for one, was also happy to see the inclusion of the Edmonton Obesity Staging System in their reflections on this complex issue.
This paper is certainly suggested reading for anyone interested in the link between obesity and cardiovascular disease.
Regular readers will be quite familiar with the findings that cardiometabolic health appears to be far more related to “fitness” than to “fatness” – in other words, it is quite possible to mitigate the metabolic risks commonly associated with excess body fat by improving cardiorespiratory fitness.
Now, a study by Kathy Do and colleagues from York University, Toronto, published in BMC Obesity, shows that this relationship also holds for people with quite severe obesity.
The researcher studied 853 patients from the Wharton Medical Clinics in the Greater Toronto Area, who completed a clinical examination and maximal treadmill test. Patients were then categorized into fit and unfit based on age- and sex-categories and in terms of fatness based on BMI class.
Within the sample, 41% of participants with mild obesity (BMI<35) had high fitness whereas only 25% and 11% of the participants with moderate (BMI 35-40) and severe obesity (BMI>40), respectively, had high fitness.
Individuals with higher fitness tended to be younger and more likely to be female.
While overall fitness did not appear to be independently associated with most of the metabolic risk factors (except systolic blood pressure and triglycerides), the effect of fitness in patients with severe obesity was more pronounced. Thus, the prevalent relative risk for pre-clinical hypertension, hypertriglyceridemia and hypoalphalipoproteinemia and pre-diabetes was only elevated in the unfit moderate and severe obesity groups, and fitness groups were only significantly different in their relative risk for prevalent pre-clinical hypertension within the severe obesity group.
Similarly, high fitness was associated with smaller waist circumferences, with differences between high and low fitness being larger in those with severe obesity than with mild obesity.
Based on these findings, the researchers conclude that the favourable associations of having high fitness on health may be similar if not augmented in individuals with severe compared to mild obesity.
However, it is also apparent based on the rather low number of “fit” individuals in the severe obesity category (only about 1 in 10), that maintaining a high level of fitness proves to be more challenging the higher the BMI.
Another article in the 2018 JAMA special issue on obesity is one by Susan and Jack Yanovski and deals with the issue of using a precision or “personalised” approach to obesity prevention and management.
As we know, there are myriad factors that can lead to obesity (environmental, genetic, psychological, medical, etc., etc., etc.), with each patient having their own story and set of drivers and barriers.
Furthermore, we know that for any given treatment (whether behavioural, medical, or surgical) there is wide variation in individual outcomes.
So, being able to match the right treatment to the right patient, or even better, reliably predict a given patient’s response to a specific treatment could potentially improve outcomes and reduce patient burden and costs.
However, as the authors note, currently the only real predictor to treatment response is how well patients respond during the early part of treatment. Thus, we know that patient who lose a significant amount of weight during the first few weeks of medical treatment, tend to have the best long-term success in terms of weight loss.
However, this approach is also rather limited. In my own practice, I regularly see patients, who initially do well with behavioural, medical or surgical treatments, but eventually struggle, as well as patients who take longer to respond to a treatment before ultimately doing fine in the long term.
We are of course a long way off from having any kind of genetic or other testing that would reliably predict patient responses to treatment.
While this may become possible in the future, I am not holding my breath.
Not only is every patient’s story different, but the many factors that can determine response (societal, behavioural, psychological, biological, etc.) are almost endless and, moreover, can even vary over time in a given individual.
In fact, for most complex chronic diseases (e.g. diabetes, hypertension, depression, etc.), finding the best treatment for a given patient continues to be “trial and error”, or in other words, “empirical”.
Despite all the progress in genetic research, this has not really changed for most other complex chronic diseases like hypertension, type 2 diabetes, or dyslipidemia (despite a few rare but notable exceptions).
Moveover, as the authors point out, there are many other factors that will determine whether or not a given patient even has access to certain treatments, irrespective of whether or not that treatment is indeed the best treatment for them.
Currently, the best we can do, is to try to understand the drivers and barriers that each of our patients face and discuss with them the best treatment options available to them given their situation and circumstances.
Whether a more precise approach is ever likely (as the authors hope), clearly remains to be seen, but based on the progress made in for other complex chronic conditions, for which similar approaches have been tried, I am perhaps far less optimistic than the authors.
But, then again, I am happy to be proven wrong.
In addition to the series of article on long-term outcomes in bariatric surgery, the 2018 special issue of JAMA on obesity, also features several articles discussing the potential role of taxing or otherwise regulating the use of sugar-sweetened beverages (SSB) as a policy measure to address obesity.
In a first article, Jennifer Pomeranz and colleagues discuss whether or not governments can in fact require health warnings on advertisements for sugar-sweetend beverages. The discussion focuses on an injunction issued by the Ninth Circuit Court on the enforcement of San Francisco’s requirement that sugar-sweetened beverage (SSB) advertisements display a health warning statement, finding that this law likely violated the First Amendment rights of advertisers of SSBs.
The background for this court decision was the fact that San Francisco passed a law requiring SSB advertisers to display: “WARNING: Drinking beverages with added sugar(s) contributes to obesity, diabetes, and tooth decay. This is a message from the City and County of San Francisco.”
In its decision, the court felt that the proposed warning label was not scientifically accurate, as it focussed exclusively on “added sugar(s)” rather than sugars overall. It appears that there is no scientific evidence suggesting that “added sugars” are any more (or less) harmful than the “natural” sugar occurring in any other foods or beverages).
However, as the authors argue, warning on SSB may well be warranted as
“In addition to being a major source of added sugar in the US diet, the liquid form of SSBs could enable rapid consumption and digestion without the same satiety cues as solid foods. SSBs also contain no relevant ingredients to provide offsetting health benefits, in comparison with sweetened whole grain cereals, nut bars, yogurt, or other foods with added sugars, which can have healthful components. Furthermore, the associations of SSBs with weight gain, obesity, type 2 diabetes, and heart disease are each stronger and more consistent than for added sugars in solid foods. In addition, compared with other foods containing added sugars, SSBs are the only source for which randomized controlled trials have confirmed the observational link to weight gain.”
Another point of contention identified by the court was related to the fact that the warning stated harm irrespective of quantity and would have been more accurate had it included the term “overconsumption” or at leas the qualifier “may”.
Here, the authors argue that,
“health risks of SSBs increase monotonically. Thus, use of the word “overconsumption” would not be scientifically accurate because there is no clear threshold effect between SSB consumption and harm. Yet, due to potential individual variation in responses, incorporating the word “may” or “can” would be scientifically accurate and are used in alcohol and smokeless tobacco warnings.”
The third objection by the court was related to the proposed size and rectangular border requirements of the warning, which was considered to be “unduly burdensome” – a point that the authors concede could be dealt with by modify formatting requirements by slightly reducing size, permitting “hairline” borders, or using other methods to ensure prominence and conspicuousness.
.In a second article on the issue of SSBs, Lisa Powell and Matthew Maciejewski discuss the case for taxing SSBs, noting they are the largest contributor of added sugar in the US diet, accounting for approximately 6.5% of total daily calories among adults and 7.3% among youth (ages 2-19 years) and approached 8% to 9% of daily calories among minority populations and 9% to 10% among low-income households. In addition consumption of SSBs have been associated with obesity as well as type 2 diabetes, cardiovascular disease, dental caries, and osteoporosis.
As the authors point out, for SSB taxes to be effective, the increased cost of SSBs has to be passed on to the consumer (“pass-through) and the consumer has to respond by decreasing their consumption (“price elasticity”). In places where SSB taxes have been implemented (e.g. Mexico), both effects have been seen, suggesting that an SSB tax can indeed change consumer behaviours.
However, as the authors also note, so far there is little evidence directly demonstrating that such changes have translated into actual health outcomes (for obesity or otherwise).
Nevertheless, the authors feel that an SSB tax can effectively decrease the overall consumption of these beverages and should perhaps be extended even further to include all forms of sugary drinks including 100% fruit juice. For this approach to be broadly acceptable, it would also be important to dedicate any revenue from these taxes to specific educational or public health purposes.
Finally, a third article on this issue by John Cawley deals with an interesting “quasi experimental” pass-through effect of SSB taxes at the Philadelphia International Airport, which happens to straddle the city border, with some terminals in Philadelphia that are subject to the beverage tax (1.5 cents per ounce), and other terminals in Tinicum that are not.
The study included 31 stores: 21 on the taxed side of the airport (Philadelphia) and 10 on the untaxed side (Tinicum).
As the authors found, following the implementation of the SSB tax in Philadelphia, the average price of SSBs increased on both the taxed and untaxed side of the airport (albeit more so on the taxed side). Using only data for taxed stores, the percentage of the tax passed on to consumers was 93%. Overall, however, the price difference between the taxed and untaxed stores was about 0.83 cents per ounce (a 55% relative pass-through rate).
Thus, while the tax did have a significant effect on SSB pricing in Philadelphia, it appears that the non-taxed stores simply went along to increase their profit margins accordingly.
Whether or not these changes in pricing had any impact on actual SSB sales or consumption was not reported.
Together, these studies certainly support the statement by Powell and Maciejewski that
“SSB taxes are likely to remain controversial for some time and policy makers will have a number of issues to consider as they formulate and implement fiscal policies.”
“SSB taxation can only be one approach to what must be a multipronged public health strategy to reduce obesity via improved diets and increased activity. The fact that intake of SSBs has declined over the past decade and the obesity epidemic has continued unabated suggests that reducing SSBs alone is not the sole solution. Adults and youth who frequently consume SSBs are more likely to engage in other unhealthy behaviors (eg, inactivity, greater fast-food consumption), so population-based policies specifically targeting these behaviors need to be designed in concert with SSB taxes. Although SSB consumption remains high in the United States, particularly among vulnerable populations, and taxation is a viable tool for curbing its consumption, the long-run intended and unintended effects of SSB tax policy are yet to be determined. The debate on its merits as an effective tool to improve health outcomes will be greatly informed by rigorous evidence on consumption, sugar intake, and body weight both on average and within vulnerable populations (children, minorities, low-income individuals).”