Monday January 24 2011
Health at 'every' size?
The Daily Mail says that “staying fat may be better for your health”. The newspaper reports that there is evidence that “overweight people live longer than normal” and that they “are also more likely to survive certain health conditions, such as type 2 diabetes, heart disease and kidney failure”.
The news is based on a research article that discusses the merits of promoting “health at every size”. It puts forward the idea that overweight people would receive greater health benefits from learning to rely on internal cues to direct their eating and building activity into their day than they would from focussing specifically on losing weight. It quoted six relevant studies that found that the new approach improved various health behaviours, as well as psychosocial and physiological outcomes. However, the trials mentioned were small, short-term (most lasted a year or less) and in women only. The studies also did not appear to assess long-term outcomes such as mortality or risk of cardiovascular disease.
Suggesting that individuals should be encouraged to have healthy behaviours at any weight does seem to make sense, but there needs to be more research to determine the long-term health benefits of this approach before it can be recommended over conventional appraoches.
Where did the story come from?
The review in question was written by two researchers from the University of California and Coventry University. They did not report any sources of funding for this specific article, although the authors reportedly speak and write on the concepts discussed in the article and sometimes receive payments for these activities. One author receives funding from the West Midlands Nursing, Midwifery and Allied Health Professions Research Training Award. The review was published in the open access, peer-reviewed Nutrition Journal.
The Daily Mail reported on this article, saying that it “includes analysis of 350,000 people in the US”. It did not make clear that the current study was summarising previous research, and that this “large study” was not in fact a single study but an analysis of 26 pooled studies in a previous systematic review. This systematic review, which was mentioned in the more discursive part of the current review, examined the association between weight and longevity rather than specifically looking at the “health at every size” approach, which was the focus of the current narrative review.
What kind of research was this?
This was a narrative review debating whether there should be a shift in focus from promoting weight loss in overweight and obese individuals to promoting “health at every size”, an approach that concentrates on body acceptance, using internal processes (such as hunger and fullness) to regulate eating, and finding enjoyable ways to build more activity into daily routines.
The authors say that although interventions involving diet, exercise and other behavioural changes can reliably lead to weight loss in the short-term, most people are not able to maintain this weight loss in the longer-term and therefore do not achieve the potential benefits of reduced weight. They also suggest that these weight-focused interventions may have unintended side effects, such as contributing to cycles of weight loss and regain, preoccupation with food and body image, lower self-esteem and eating disorders.
The authors say that concentrating on weight loss takes focus away from other health goals and issues that also affect health. They say that there is a growing movement towards focusing on “health at every size” rather than weight loss and dieting.
A narrative review is typically used as a way of discussing new or emerging theories.
What did the research involve?
The authors discuss the evidence and rationale behind “health at every size” (HAES) in several sections.
First, they carried out a search of one major literature database to identify randomised controlled trials (RCTs), comparing the effects of interventions focusing on HAES and size acceptance with traditional interventions focusing on weight loss or weight maintenance. They summarise the findings of the RCTs they identified. Our report focuses on this aspect of the review.
The researchers then go on to list the assumptions underlying the conventional weight-focused approach, and discuss the evidence regarding these assumptions. They detail and discuss the ways in which HAES differs from weight-focused approaches. Finally they discuss the clinical and public health ethics surrounding these different approaches.
What were the basic results?
The researchers identified six fully published RCTs based on HAES principles. These RCTs included between 60 and 185 people each, with 620 people included in total. They all included overweight or obese women, some of whom were chronic dieters or binge eaters. The studies compared HAES approaches with various alternatives including social support, dieting, cognitive behavioural treatment, education and weight loss approaches. They lasted for between 26 and 78 weeks post-treatment.
They found that:
- Of five RCTs assessing health behaviours, four found statistically significant improvements in the HAES group compared with the control in at least one measure (e.g. activity or eating behaviours).
- Four RCTs assessed psychosocial outcomes, and three of these found statistically significant improvements in the HAES group compared with the control in at least one area (e.g. self-esteem, body image, depression).
- Three out of four RCTs assessing metabolic outcomes showed significant improvements in at least one of these measures, such as blood pressure and blood lipids.
- The actual figures for individual measures were not shown in the review, but the improvements seen were reported to be “statistically and clinically relevant”.
- None of the measures showed any adverse change with HAES approaches.
Another RCT published only as a conference abstract, a non-randomised controlled study and five uncontrolled studies was also described as having positive results, but no further details were provided.
How did the researchers interpret the results?
The researchers concluded that: “From the perspective of efficacy as well as ethics, body weight is a poor target for public health intervention.” They say that there is “sufficient evidence to recommend a paradigm shift from conventional weight management to HAES”. They also call for further research into the unintended consequences of weight-focused approaches, and into the best “health at every size” interventions.
This narrative review has summarised the evidence and rationale behind the “heath at every size” (HAES) approach, which focused on following a healthy lifestyle rather than weight loss.
- The RCTs identified were all small, had relatively short follow-up periods and only appeared to include women.
- To determine whether HAES approaches do produce greater health benefits in the long run there must be much larger, longer studies comparing standardised HAES approaches with accepted weight-loss focused approaches in both men and women.
- The review did not provide information about the methods of the RCTs (e.g. how they assessed the outcomes), or quantitative results of these RCTs. Therefore it was not possible to judge the quality of this research or the magnitude of benefits seen with HAES.
- Although a search was performed for RCTs looking at HAES approaches, other sections of the article are more descriptive in nature and may not have included all relevant research.
While suggesting that individuals should be encouraged to have healthy behaviours at any weight does seem to make sense, it is not possible to say yet whether HAES approaches are more effective than other approaches. In order to evaluate the health benefits of HAES there must be further research looking at it as a long-term approach in larger populations and directly comparing it with weight-loss measures.