We know that non-weight-loss, body acceptance approaches to health (sometimes called Health At Every Size) can work in terms of helping people at a range of weights achieve better markers of physical health. For example, several randomized controlled trials have shown improvements in cholesterol and blood pressure in “overweight” and “obese” women using these approaches. But how?
Generally these approaches don’t cause weight loss — they’re not designed to cause weight loss, and the focus is on body and self acceptance. One answer may lie in the lifestyle improvements women in these studies made. Various studies found that they became more active, and/or ate a higher quality diet, and/or engaged in less binge eating. So maybe it’s simply those positive changes that caused the physical improvements.
For hypertension especially, though, I wonder if some improvement was due to the effect of body acceptance interventions on either self-esteem, body image, or experiences of anti-fat bias and discrimination. The link between exposure to racial discrimination and hypertension among African-Americans (who are at relatively higher risk for hypertension) is well known, and researchers have learned some interesting things about that relationship. For example, internalized negative attitudes towards African-Americans are even more strongly predictive of poor heart health among African Americans than perceived discrimination. In addition, perceived ethnic density — that is, reporting that you live in a community with lots of other people of your ethnicity — may buffer some of the effects of racism on health in general among minority communities.
Perhaps connecting to a community of other higher-weight folks who are practicing body acceptance, standing up to size-based discrimination, and challenging their internalized anti-fat bias is what leads to some of these improvements, not just better eating and exercise.