A BATTLE OVER THE BEST DIET

A dizzying array of weight loss programs are vying for our attention — and our dollars

On any given day, just over one in five American adults are actively trying to lose weight. An additional 50% have tried dieting, but have retreated to old routines while mounting the will to try again.

Results will be mixed, ensuring the nation’s sprawling diet industry a steady flow of revenue. According to Marketdata Enterprises, which tracks the weight-loss industry, we spend more than $60 billion a year on diet foods, books, coaching, meetings, mobile apps and meal plans to help with weight loss.

Fads come and go. Confusion reigns. And failure is common.

Physicians generally aren’t much help. Under the Affordable Care Act, primary care doctors are expected to advise all obese patients to lose weight and counsel them on how to do so. Research tells us a doctor’s recommendation can be a powerful spur to weight loss. But few are equipped to lead patients to the specific plan that will work best for them.

It doesn’t help that the science of what works is filled with gaps and contradictions, or that the diet plan that works for one person may not work well for another.

It’s simple to say that to lose weight, calories out must exceed calories in — and that to reverse obesity, just continue the process. But experts say that losing weight, and maintaining that loss, is vastly more complex.

It’s a matter of evolution — adaptations to famine and drought have helped design the human body to abhor the loss of weight. As researchers demonstrated in a study of people who lost about 14% of their starting weight with a very-low-calorie diet, the body undergoes a host of changes to ensure that the weight is regained.

Metabolic rate drops, allowing the post-diet body to do more with fewer calories. Myriad hormonal signals shift in ways that boost appetite. Those changes endure for at least a year after weight is lost, the researchers found. Even after weight comes back, many of those changes persist, ensuring further weight gain.

These findings, which have been replicated by other studies, help explain why 95% of dieters will regain all the weight they lost within five years, and most will gain a few extra pounds as well.

Results like that have fueled a growing expert consensus that “dieting” — temporary adherence to a regimen of eating that causes weight loss — is a fool’s errand. When weight must be lost, experts say, it should be with strategies and eating patterns that can be maintained over the long haul.

Those strategies should be sustainable enough to support longterm health and nutrition. And they should be tolerable enough to stick with through a “weight loss maintenance” period that may last a lifetime.

In short, diets must become a way of life, not a painful interlude, says Dr. Louis J. Aronne, a weight-loss specialist at Weill Cornell Medical College in New York City.

“The diet that people find easiest to comply with is the one that works best for them,” Aronne says.