The Science Behind Health At Every Size (HAES)
Regular readers of these pages will recall my past criticism of the use of BMI in individual counseling, my introduction of the Edmonton Obesity Staging System (which classifies obese patients not by how “big” they are but rather by how “sick” they are), and the many previous posts that recommend avoidance of weight gain rather than obsessing about numbers on the scale. In fact, I have gone on record with a previous post asking the question whether or not advising ALL patients to lose weight may in fact be unethical.
Without reiterating any of my past arguments, I would like to point readers to a paper by Linda Bacon (University of California, USA) and Lucy Aphramor (Conventry University, UK), just published in the Journal of Nutrition, which addresses the science behind the Health at Every Size (HAES) movement.
For readers who may be unfamiliar with the HAES paradigm, the underlying assumption, based on the high rate of recidivism seen with weight-loss efforts, as explained by the authors, is that:
“…this weight focus is not only ineffective at producing thinner, healthier bodies, but may also have unintended consequences, contributing to food and body preoccupation, repeated cycles of weight loss and regain, distraction from other personal health goals and wider health determinants, reduced self-esteem, eating disorders, other health decrement, and weight stigmatization and discrimination.”
Proponents of the HAES movement challenge the value of promoting weight loss and dieting behavior and argue for a shift in focus to weight-neutral outcomes.
So what supports this seemingly radical idea?
For one, as reviewed by the authors, a comprehensive search of the literature reveals at least six randomised controlled trials indicating that a HAES approach (focussing on promoting health behaviours and size acceptance rather than weight loss) is associated with statistically and clinically relevant improvements in physiological measures (e.g. blood pressure, blood lipids), health behaviors (e.g. physical activity, eating disorder pathology), and psychosocial outcomes (e.g, mood, self-esteem, body image). None of these studies found adverse changes in any variables.
The authors then discuss the literature underlying the common assumptions regarding the relationship between excess weight and mortality (e.g. weak relationship over a wide range of BMI; better survival in patients with chronic diseases at higher BMIs) or excess weight and morbidity (unresolved causality questions – e.g. does insulin resistance cause obesity or does obesity cause insulin resistance?), confounding positive effects of behaviour changes (e.g. improved diet and greater physical activity) and/or negative effects of weight cycling).
They also challenge the widely held assumption that anyone who is determined can lose weight and keep it off through appropriate diet and exercise, by pointing out that most people will regain any weight lost (and often more), and that there is little support for the idea that (weight-loss) diets lead to lasting weight loss or health benefits.
They point out that rather than being a practical or positive goal, the pursuit of weight loss generally does little more than promote weight cycling, psychological stress, and expose the body to high levels of persistent organic pollutants (POPs), which accumulate in adipose tissue and are released during weight loss. In addition, evidence from the eating disorder literature indicates that an emphasis on weight control can promote eating disordered behaviours and body dissatisfaction, which in turn is associated with binge eating, lower levels of physical activity, and increased weight gain over time.
In contrast to the widespread assumption that the only way for overweight and obese people to improve health is to lose weight, the authors point out that most health indicators can be improved through changing health behaviors, regardless of whether or not weight is lost.
Finally, the authors even challenge the assumption that obesity leads to higher health care costs by arguing that increased health care costs in obese individuals may be due to confounding variables such as (lower) physical activity, (poorer) nutrient intake, history of weight cycling, degree of discrimination, or simply due to the negative consequences of weight focus, which may include eating disorders, diet attempts, weight cycling, reduced self-esteem, depression, and discrimination. In addition, health care costs for people with higher BMIs may be artificially inflated because these individuals are subjected to more medical testing and treatment.
In several instances, the authors also address the issue of weight stigma and point out that when studies compare people of similar age, gender, education level, and rates of diabetes and hypertension, their body image appears to have a much bigger impact on health than their body size.
Although both authors declare their conflict of interest in that they both identify themselves as “HAES” practitioners, the paper is largely well-balanced and referenced.
One notable exception, however, is the brief passage dealing with the assumption that weight loss can prolong life. Here they rightly point out that liposuction (i.e. simple surgically removing fat) does not improve metabolic markers or health, but fail to mention the increasingly robust evidence that bariatric surgery (at least in patients with severe obesity) not only dramatically improves quality of life and reduces comorbidities but also significantly increases life expectancy (although the authors may well argue that patients, who have had bariatric surgery experience these health improvement because they eat healthier, are more physically active, and probably feel much better about themselves, rather than due to the actual weight lost).
With regard to the ethics of public health interventions to reduce obesity, the authors state:
“Policies which promote weight loss as feasible and beneficial not only perpetuate misinformation and damaging stereotypes, but also contribute to a healthist, moralizing discourse which mitigates against socially-integrated approaches to health. While access to size acceptance practitioners can ameliorate the harmful effects of discrimination in health care for individuals, systemic change is required to address the iatrogenic consequences of institutional size discrimination in and beyond health care, discrimination that impacts on people’s opportunities and health.”
The article closes with “guidelines”, which the authors state are supported by the Association for Size Diversity and Health (ASDAH), to assist professionals in implementing HAES strategies into practice:
- Interventions should meet ethical standards. They should focus on health, not weight, and should be referred to as “health promotion” and not marketed as “obesity prevention.” Interventions should be careful to avoid weight-biased stigma, such as using language like “overweight” and “obesity.”
- Interventions should seek to change major determinants of health that reside in inequitable social, economic and environmental factors, including all forms of stigma and oppression.
- Interventions should be constructed from a holistic perspective, where consideration is given to physical, emotional, social, occupational, intellectual, spiritual, and ecological aspects of health.
- Interventions should promote self-esteem, body satisfaction, and respect for body size diversity.
- Interventions should accurately convey the limited impact that lifestyle behaviors have on overall health outcomes.
- Lifestyle-oriented elements of interventions that focus on physical activity and eating should be delivered from a compassion-centered approach that encourages self-care rather than as prescriptive injunctions to meet expert guidelines.
- Interventions should focus only on modifiable behaviors where there is evidence that such modification will improve health. Weight is not a behavior and therefore not an appropriate target for behavior modification.
- Lay experience should inform practice, and the political dimensions of health research and policy should be articulated.
Obviously, this line of reasoning will find its strongest critics amongst the “weight-loss industry” as well as the many, who may have personally experienced health benefits from losing weight (although HAES enthusiasts will likely argue that these benefits result from the accompanying lifestyle changes rather than from the actual weight lost).
Personally, I plan to keep a very open mind on this issue (as reflected in many of my posts).
In my own practice, I routinely counsel patients, who pursue unrealistic and unsustainable weight loss goals, to focus on improving health behaviours rather than obsessing about numbers on their scale.
On the other hand, I also routinely recommend and discuss realistic weight-loss targets with patients in whom I see severe health problems that can likely be ameliorated or reversed by weight loss (or, as HAES practitioners may argue, the behaviour changes that lead to this weight loss).
I also routinely recommend bariatric surgery to patients who I believe will benefit, while (almost as often) discouraging other patients from considering surgery when the risks appear to outweigh any potential benefits.
As so often in medicine, I believe that the best approach probably lies in finding the middle ground between the two extremes of either automatically recommending weight loss to all patients with a BMI over 30 or simply accepting any amount of excess weight irrespective of its impact on health or quality of life.
Perhaps this is where clinical practice becomes more of an art than a science?
Hat tip to Catherine for pointing me to this article
Bacon L, & Aphramor L (2011). Weight Science:Evaluating the Evidence for a Paradigm Shift. Nutrition journal, 10 (1) PMID: 21261939