For decades there has been an accepted definition of diet in science and in society as a whole. Michael Lowe, PhD, professor in Drexel University’s College of Arts and Sciences, recently re-evaluated decades of nutritional research to re-evaluate the way researchers and the public define – and understand – diets and the culture of weight loss define.
According to Lowe, the most pressing problem is not the diet itself, but the collision of the modern food environment with our immutable evolutionary heritage that drives us to find and consume food when it is available. In today’s food environment, this combination makes permanent control of food intake (and usually body mass) extremely difficult.
These challenges are compounded when there is a genetic predisposition to excess weight gain. Lowe, along with PhD students Joanna Chen and Simar Singh, explains how this background relates to diet in two recently published articles in Appetite and Physiology & Behavior.
Research into the definition and consequences of diets has been a source of controversy for years. This controversy has spread to the public, especially as eating disorders and obesity have become more common. One of the earliest and longest-running controversies concerns the low-key food created by University of Toronto Professors Peter Herman and Janet Polivy in the mid-1970s.
Michael Lowe, PhD, Professor, College of Arts and Sciences, Drexel University
Lowe and colleagues suggest that historical trends have influenced the development of restraint theory in ways that inappropriately challenged the practice of weight management dieting. In the 1970s and 1980s, two worrying health problems began to increase significantly: obesity and eating disorders that accompany binge eating (bulimia nervosa and binge eating disorder). Although obesity and binge eating sometimes co-exist, one often occurs without the other, Lowe explained.
The basic problem is that what they call “chronic diet” (or “restrained eating”) is measured by restraint theorists of weight fluctuations and emotional overuse of food, Lowe said. Herman and Polivy attributed the latter traits to chronic dieting, but at the time (mid-1970s) they could not have known that Western societies were on the verge of a double epidemic of obesity and binge eating. So they failed to realize that diets were usually not the cause of eating and weight problems, but rather a consequence and symptom of a nascent, toxic food environment.
“In other words, whether dieting is ‘good or bad’ is analogous to whether taking methadone is good or bad,” Lowe said. “If someone is on a weight loss diet because of unwanted weight gain or loss of control, then dieting will at least temporarily improve that condition as a result of a pre-existing susceptibility to obesity or loss of control over eating.”
He added that the best way to curb dieting is to make sweeping changes in the food environment, both in society and in the home. Understanding that diets are more of a scapegoat than a bad guy should focus people’s concerns on the real source of our obsessions with food, weight, and diet: a food environment as unhealthy as the “tobacco environment” in the 1950s.
Lowe’s final difference is that there is a small fraction of the population for whom weight loss is really harmful, namely those with anorexia or bulimia nervosa. Also, at least among the disordered eaters who are clinically noticeable, they also tend to reach elevated BMI before embarking on radical dieting and extreme weight loss.
This leads to a condition that Lowe and colleagues call weight suppression, which paradoxically helps maintain their eating disorder. For these individuals, a weight loss diet was indeed dangerous. But again, an unhealthy eating environment is the likely culprit that led to weight gain causing them to eat unhealthily to find a solution.
Chen, JY, et al. (2021) The Food Restraint Wars: Proposed Resolution to a Primary Battle. Physiology & behavior. doi.org/10.1016/j.physbeh.2021.113530.