WE RELY ON OTHERS TO SHARE OUR VICTORIES AND DEFEATS.

Each week we anti-calorie commandos gather at Brooker’s for half an hour or so to exchange views and advice, then sit for an hour-long talk by Brooker or a guest motivational speaker. We then go back to the battle, refreshed. We are not, we eventually realize, single-combat warriors. We rely on others to share our victories and defeats. Absorbing this process, I’ve come to respect the wisdom that’s made Alcoholics Anonymous the most effective self-help society in the world. So far, unfortunately, there’s no equivalent organization for the obese.

Recent research has provided a partial explanation for one of the most frustrating aspects of weight loss. Many people, after losing a great deal of weight, put it right back on again. This worldwide mystery has puzzled researchers for years. “It has always seemed strange to me,” Joseph Proietto said to a reporter a few years ago. He runs a weight-loss clinic at the University of Melbourne. “These are people who are very motivated to lose weight, who achieve weight loss most of the time without too much trouble — and yet, inevitably, gradually, they regain the weight.”

Why? The beginning of an answer came from a reality TV show on NBC, The Biggest Loser. In 2009 Danny Cahill was the winner. He started out at 430 pounds and lost 239 in seven months. At 191 he became a national celebrity. “I’ve got my life back,” he said. “I feel like a million bucks.” He went on talk shows to explain how he did it. But in a few years he gained 100 pounds, and most of the other 16 contestants on that season also gained. Only one contestant now weighs less today than in 2009.

It happened that Kevin Hall of the National Institutes of Health had decided to follow the progress of the 2009 contestants. He discovered that their metabolism was slow when their dieting ended (which was normal) but as the years went by their metabolism did not recover. As a New York Times reporter noted, “They became even slower, and the pounds kept piling on. It was as if their bodies were intensifying their effort to pull the contestants back to their original weight. They showed just how hard the body fights back against weight loss… their metabolisms had slowed radically and their bodies were not burning enough calories to maintain their thinner sizes.”

It suggests that unseen wars are raging within us, beyond our knowledge or control. This whimsical notion was suggested decades ago by Lewis Thomas, the biologist who became the poet-philosopher of medicine and won widespread fame with best sellers like The Lives of a Cell. He suggested that it’s possible the private functions of our bodies are performed entirely by autonomous one-celled creatures that aren’t aware they are part of us and might resent it if told they were. Thomas’s fictional example was his way of saying that in medicine what we know remains less important than what we don’t know.