Give weight-loss diets a rest
By Abigail C. Saguy and Tamara B. Horwich
A respected cardiologist of our acquaintance recently confessed that he often tells his patients to lose weight. This may sound like good advice, but he knows better. Scores of clinical studies show that heavier patients with heart disease are, on average, less likely to die than thinner ones. Furthermore, weight loss efforts are typically counterproductive. Our cardiologist friend knows the studies but can’t quite bring himself to let go of the association between weight and health. He is not alone. In fact, the pervasive clinical and cultural bias against fat and fat people distorts medical practice, despite mounting evidence that human metabolic function is far more complex than previously understood.
It is true that heavier individuals are more likely to develop heart disease on average than are thinner patients, although it is not clear that being heavier causes heart disease. It may be that some related factor or factors — such as diet, exercise, stress, socio-economic status or a combination of these — causes both increased weight and makes one susceptible to heart disease.
That said, a growing body of evidence has shown that, among people who already have heart disease, heavier patients are less likely to die. This is so counter-intuitive that medical researchers refer to this burgeoning body of research as “reverse epidemiology” or the “obesity paradox.”
A recent study has shown that this “obesity paradox” holds for Type II Diabetes as well. Granted, people in the general population are more likely to develop Type II Diabetes in the first place if they are heavier, although the causal pathways remain unknown. However, among those who develop Type II Diabetes, many are in the “normal weight” category. Furthermore, among Type II Diabetes patients, the heavier ones are less likely to die than their thinner counterparts.
In the general population, heavier body mass is indeed associated with cardiometabolic abnormalities (i.e., high blood pressure, triglycerides, cholesterol, glucose, insulin resistance and inflammation). However, even here, the association is far from perfect. Specifically, almost one quarter of “normal weight” people — or 16 million Americans — have metabolic abnormalities, whereas more than half of “overweight” and almost one third of “obese” people — or 56 million Americans — have normal profiles, according to a 2008 study. We are beginning to understand that it is not the quantity but rather the quality of fat in our bodies that predicts cardiovascular risk; the unseen fat deeply embedded in our internal organs, known as visceral adipose tissue, is the type of fat most likely to lead to cardiometabolic abnormalities while visible fat beneath our skin may be more metabolically benign.
These studies belie the idea that heavier or bigger bodies are automatically diseased bodies and that weight loss is a panacea. When we further consider that 90-95% of dieters end up regaining what they lose, and that use of diet drugs or supplements may be particularly dangerous in patients with heart disease, the insistence on weight loss is more puzzling.
“It took a lot of self-discipline, but I finally gave up dieting,” quips a popular Facebook posting. This post is funny because it inverts the common assumption that dieting requires discipline and is a virtuous endeavor. Indeed, being fat is still widely regarded as evidence of the sins of sloth and gluttony, despite — or perhaps because — of growing talk of “obesity” as a medical problem and public health crisis. It is this conviction that being fat is morally wrong that makes it hard for doctors, as well as ordinary people, to give up dieting and dieting advice. This is all the more true in times and places, like the contemporary United States, where the socially and economically privileged tend to be thin and the disadvantaged are more likely to be heavy.
Especially distressing are studies showing that many medical professionals regard their heavy patients as lazy and non-compliant. A recent study showed that doctors treat their heavy patients with less empathy and compassion than their thinner peers. In extreme cases, convinced that excess weight is responsible for ill health and that weight loss is the solution, doctors may not conduct necessary diagnostic exams that would have pointed to the underlying cause of illness.
It is time that medical professionals give up the focus on fat. This won’t be easy; the belief that if overweight and obese patients lost weight they would be healthier is deeply embedded in both our popular and our medical culture. Yet, there is a better way. Rather than focusing on outward appearance, it would be infinitely more productive and accurate to talk about cardiometabolic risk and to recognize that there are both metabolically-healthy and metabolically-unhealthy individuals in all categories of weight. Instead of promoting weight loss, doctors should emphasize that patients of all sizes incorporate physical activity and a balanced diet into their lives. Several studies have shown that physically fit “obese” individuals have lower incidence of heart disease and mortality from all causes than do sedentary people of “normal” weight. Similarly, a recent clinical trial published in the New England Journal of Medicine showed that adopting a Mediterranean diet reduced cardiovascular risk without inducing weight loss. The sixth of May is International No-Diet Day and a good time for doctors and patients alike to give up their unhealthy focus on weight loss.
Abigail C. Saguy, PhD is Associate Professor and Vice Chair of Sociology at UCLA and author of What’s Wrong with Fat? (Oxford, 2013).Tamara B. Horwich, MD, MS is a UCLA cardiologist who has published research on the link between body mass and mortality among heart disease patients.