Science is not a sacred cow. Science is a horse. Don’t worship it. Feed it.
— Aubrey Eben
The new Health At Every Size paper, by Linda Bacon and Lucy Aphramor, is titled Weight Science: Evaluating the Evidence for a Paradigm Shift. From the abstract:
Current guidelines recommend that “overweight” and “obese” individuals lose weight through engaging in lifestyle modification involving diet, exercise and other behavior change. This approach reliably induces short term weight loss, but the majority of individuals are unable to maintain weight loss over the long term and do not achieve the putative benefits of improved morbidity and mortality. [...] A growing trans-disciplinary movement called Health at Every Size (HAES) challenges the value of promoting weight loss and dieting behavior and argues for a shift in focus to weight-neutral outcomes. [...] This paper evaluates the evidence and rationale that justifies shifting the health care paradigm from a conventional weight focus to HAES.
If it isn’t clear, this isn’t reporting new research: it’s reviewing and tying together existing research on HAES, and discussing why HAES is preferable than the traditional weight loss advice. The introduction explains the basics of Health at Every Size and the research supporting it.
Several clinical trials comparing HAES to conventional obesity treatment have been conducted. Some investigations were conducted before the name “Health at Every Size” came into common usage; these earlier studies typically used the terms “non-diet” or “intuitive eating” and included an explicit focus on size acceptance (as opposed to weight loss or weight maintenance). [...] [Only randomized controlled trials (RTCs) and] studies with an explicit focus on size acceptance were included.
Evidence from these six RCTs indicates that a HAES approach 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) [...] (See Table 1.) All studies indicate significant improvements in psychological and behavioral outcomes; improvements in self-esteem and eating behaviors were particularly noteworthy [...]. Four studies additionally measured metabolic risk factors and three of these studies indicated significant improvement in at least some of these parameters, including blood pressure and blood lipids [...]. No studies found adverse changes in any variables.
Clicking the “Table 1” link goes to a summary of studies from 1998 to 2009. Many of us are familiar with “Bacon et al, 2005 and 2007“, which refers to the study Linda Bacon, Judith Stern, Nancy Keim and Marta Van Loan conducted to compare a standard diet program with a HAES program and its follow-up report. It’s discussed in detail in Linda Bacon’s book Health At Every Size: The Surprising Truth About Your Weight and in a few articles. The other studies primarily vary in what types of outcomes they measured.
The next major section details the assumptions people make about the weight-loss paradigm. Each of these assumptions is discussed, with an eye to showing the actual evidence (or lack thereof). For example:
Assumption: The only way for overweight and obese people to improve health is to lose weight
Evidence: That weight loss will improve health over the long-term for obese people is, in fact, an untested hypothesis. One reason the hypothesis is untested is because no methods have proven to reduce weight long-term for a significant number of people. Also, while normal weight people have lower disease incidence than obese individuals, it is unknown if weight loss in individuals already obese reduces disease risk to the same level as that observed in those who were never obese [...].
As indicated by research conducted by one of the authors and many other investigators, most health indicators can be improved through changing health behaviors, regardless of whether weight is lost [...]. For example, lifestyle changes can reduce blood pressure, largely or completely independent of changes in body weight [...]. The same can be said for blood lipids [...]. Improvements in insulin sensitivity and blood lipids as a result of aerobic exercise training have been documented even in individuals who gained body fat during the intervention [...].
This is followed by a discussion of the support for using a HAES approach instead of a weigh-loss approach; the components of HAES (body acceptance, intuitive eating, and being active); and the ethics of using a HAES approach vs a weight-loss approach. Naturally, being an academic paper, there’s an abstract, appendix, disclosures of conflicts of interest, etc.
Overall, the discussion I’ve seen of this paper seems to reflect people’s expectations. The paper isn’t about HAES per se, it’s about how HAES is a better approach to improving health in fat people than prescribing weight loss (assuming, of course, that health improvements are desired). The value of the paper for me is that it:
- Summarizes the current state of HAES evidence, with bibliography. There isn’t just one study that supports HAES — multiple researchers have had similar results.
- Argues the case for HAES in an organized fashion.
- The full text of the paper is freely available on the web. You don’t have to get it from the library.
- It helps show the current holes in the research. There isn’t a randomized controlled trial comparing a diet approach vs a HAES approach in men, for example. Most studies did not track physiological measures (e.g. blood pressure, blood lipids) in dieters vs the HAES participants.
The ethics discussion is also interesting. Many doctors who are asked in the media about “If diets don’t work, what do you tell patients?” tend to come back with “Well, keep trying” or weight-loss surgery (as if that’s not a diet). Linda Bacon and Lucy Aphramor argue outright that “the HAES paradigm shift may be required for professional ethical accountability.”
Also: NYTimes blog post on HAES and this paper.