Human evolution makes dieting a bit of a challenge.

For decades, there has been an accepted definition of dieting in academia, and in society as a whole. Michael Lowe, PhD, a professor in Drexel University’s College of Arts and Sciences, has recently reevaluated the decades of dieting research to redefine the way researchers and the public define – and therefore understand – dieting and the culture of weight loss.

According to Lowe, the most pressing problem is not dieting 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 lasting control of food intake (and, usually, body mass) exceptionally difficult. These challenges are further magnified if there is a genetic predisposition toward excessive weight gain. Lowe, along with doctoral students Joanna Chen and Simar Singh, explain the relation of this background to dieting in two recently published papers in Appetite and Physiology & Behavior.

“Research regarding the definition and consequences of dieting has generated controversy for years. This controversy has spilled over into the public domain, especially as eating disorders and obesity have become more prevalent,” said Lowe. “One of the earliest and longest-lasting controversies involves the restrained eating framework created by University of Toronto professors Peter Herman and Janet Polivy in the mid-1970s.”

Lowe and colleagues suggest that historical trends impacted the development of the Restraint Theory in ways that inappropriately impugned of the practice of dieting for weight control. In the 1970s and 1980s, two worrisome health problems started to increase substantially: obesity and eating disorders involving binge eating (bulimia nervosa and binge eating disorder). Though obesity and binge eating sometimes co-exist, one often occurs without the other, Lowe explained. 

The fundamental problem is that restraint theorists’ measure of what they call “chronic dieting” (or “restrained eating”) actually measures weight fluctuations and emotional over-involvement with food, according to Lowe. Herman and Polivy attributed the latter characteristics to chronic dieting but at the time (the mid-1970s) they couldn’t know that western societies were on the brink of dual epidemics of obesity and binge eating. They therefore didn’t realize that dieting was not usually the cause of eating and weight problems but a consequence and symptom of an emerging, toxic food environment. 

“Stated differently, asking whether dieting is ‘good or bad’ is analogous to asking if taking methadone is good or bad,” Lowe said. “If someone goes on a weight loss diet because of unwanted weight gain or loss of control eating, then dieting will at least temporarily improve these conditions. Just as taking methadone is a consequence of a pre-existing susceptibility to drug addiction, dieting is usually a consequence of a pre-existing susceptibility to obesity or loss of control eating.” 

He added, the single best way to curb dieting is to make widespread changes to the food environment, both societally and within the home. Helping individuals understand that dieting is more a scapegoat than a villain should refocus people’s concerns on the true source of our obsessions with eating, weight and dieting: a food environment that is as unhealthy as the “tobacco environment” was in the 1950s. 

Lowe’s final distinction is that there is a small proportion of the population for whom weight loss dieting truly is pernicious, which is those with anorexia or bulimia nervosa. At least among those eating disordered individuals who come to clinical attention, they also tend to reach elevated BMIs before engaging in radical dieting and extreme weight loss. This results in a state Lowe and colleagues call weight suppression, which paradoxically helps perpetuate their eating disorder. For these individuals, weight loss dieting was indeed dangerous. But again, an unhealthy food environment is the likely culprit that caused them to gain weight in the first place, thereby prompting them to engage in unhealthy dieting to find a solution.