Dieting Failure: The Real Reason It Is So Hard to Keep Weight Off Once Lost
It’s a familiar tale told countless times. A woman (or a man) is overweight. She joins Weight Watchers and exercises and watches the calories and through sheer hard work and discipline she loses the weight she was aiming to lose. She looks and feels great. A year later, despite all her best efforts, she is overweight again. She feels terrible and blames herself for her failure to remain fit.
But here’s the thing. It is extremely difficult for almost everyone to keep off the weight that has been lost. Recent weight loss studies point to the daunting array of biological forces arrayed against the once large successfully shrinking their size over the long haul.
Obesity is an epidemic in America. Fully one-third of American adults—79 million people—are flirting with obesity, and it is rapidly becoming the number-one health problem in the country, linked to heart disease, type 2 diabetes and even some cancers. The annual medical cost of the obesity epidemic exceeds $150 billion. The psychological toll is unquantifiable, as fat-shaming is very much alive and well. The myriad causes of obesity, which disproportionately affects African-Americans (almost half the black adult population) and Hispanics (42 percent of the Hispanic population), have been well documented: poverty, food deserts, high fructose corn syrup, processed food, fast food, and inactivity, among many other factors. Efforts to take off weight in America have spawned a vast exercise industry, including gyms, equipment, home videos, and even entertainment. There is plenty of money to be made in telling people they can lose weight and thereby change their lives.
Television’s “The Biggest Loser,” one of broadcast TV’s most popular shows, chronicles the herculean efforts of groups of obese men and women to shed pounds and become fit and healthy. Immensely moving, the journeys of these determined Americans to lose hundreds of pounds serves as a shining example to all of us that, yes, it can be done. We can lose that weight if we really want to and if we work hard enough. But there is more to the story.
Perhaps there should be a spin-off series called “The Biggest Loser: The Year After.” There is a good reason why there is no such sequel—it would be far too depressing. Most of the contestants on the series fail to keep the pounds from inexorably crawling back onto their bodies, a recent article in the New York Times recounted. Contestant Danny Cahill lost over 200 pounds, only to gain more than 100 of it back; Dina Mercado lost 75 pounds only to regain 30, so far. The story is the same for almost all of the contestants. Despite their best efforts, the weight inexorably returns—sometimes even more of it.
This depressing fact was chronicled by weight-loss doctors like Kevin Hall, a metabolism expert at the National Institutes of Health, who decided to follow "Biggest Loser" contestants for six years after their stirring TV triumphs. What he found was astounding. It seems that once large, the body actually fights to maintain or regain its largeness. This has a great deal to do with metabolism, the process by which the cells in your body transform the calories you ingest into fuel. Simpy put, if you consume more calories than your body needs, the extra calories are stored as fat. While exercise can speed up your metabolism a bit and burn a few more calories, 60-80 percent of calories your body burns are simply to maintain basic bodily functions, keeping the heart beating, the blood flowing, the lungs breathing. In other words, just sitting in the barcalounger watching “The Biggest Loser” is burning the majority of the calories you consume. This passive calorie burning is known as your resting metabolism.
It is a recognized fact that weight loss usually results in a slower resting metabolism (a process known as metabolic adaptation, or adaptive thermogenesis). That is, the body at rest burns fewer calories. Obese people, like those on “The Biggest Loser,” may be large, but their resting metabolism is normal for people in that weight category. When weight is lost, the metabolism correspondingly slows down. What Kevin Hall found in his study, however, was that once the extreme Biggest Loser weight loss program ends, a routine that includes hours and hours of exercise and calorie restriction, the pounds begin to creep back. But to his astonishment, the resting metabolism does not return to former levels. In fact, it actually gets even slower. The body is actually burning even fewer calories, resulting in even more fat storage and weight gain. Not enough calories are being burned to maintain the new physique. The body wants to be big again.
Scientists don't know why dieting brings about this slower metabolism, or why it remains slow after weight loss. Some have theorized that there is a genetic component. During prehistoric human development, hunger and malnutrition was common and the body may have evolved to slow the metabolism down in order to store fat to burn for the leaner, hungry periods humans had to survive. Other scientists have maintained that the processes are too complex to pin down one specific reason for the metabolic slowdown.
Metabolism isn’t the only driver. Hormonal components are also a big factor. In the case of the Biggest Losers, the six-year study showed that at the end of their appearances on the show, the weight loss had resulted in virtually no leptin left in their bloodstreams. Leptin is a bodily hormone that controls hunger. In its absence, a person will feel ravenously hungry, and predictably, the contestants began to gain weight as they sought to satisfy their hunger. After six years, their leptin level returned, but only to about 60 percent of the level of what it was prior to their TV appearances. As a result, their level of hunger control was still significantly impaired.
Not only that, but a National Health and Medical Resource Council study in Australia, conducted by Joseph Proietto of the University of Melbourne, found that other hormones, ones that actually compel you to eat, rose after weight loss, which combined with lack of hunger control and slower metabolism, is a recipe for weight gain. “The body puts multiple mechanisms in place to get you back to your weight. The only way to maintain weight loss is to be hungry all the time,” Proietto told the New York Times.
Weight gain is surprisingly easy. In an average year, any one of us will consume up to a million calories. We actually effectively burn most of them. Out of that million, however, if we leave just 3,000 to 5,000 calories unburned, we will gain up to two pounds a year. That is just 10 or 20 calories a day, the equivalent of one small piece of candy. In the case of the Loser contestants (and anyone who has taken off any significant amount of weight), their metabolisms were burning almost 500 calories fewer per day than people in their weight categories might be expected to burn (the equivalent of an entire meal a day being stored away as fat). It is understandable that an extra 500 calories a day will lead to rapid weight gain, unless you are willing to put in even more exercise than you already do, all the while restricting calories while you are feeling ravenously hungry due to hormonal influence.
These devastating findings notwithstanding, all is not hopeless for those looking to drop a few pounds. Research at the Mayo Clinic found that the drop in resting metabolism was not nearly so steep in cases where just a minor weight loss was concerned. Subjects who gradually lost up to 20 pounds over several months seemed to maintain a reasonable resting metabolism. Fifteen percent of people who lose 10 percent or more of their body weight manage to keep it off. Common factors among successful weight losers are calorie restriction, regular exercise, portion control at meals, a healthy breakfast, and weekly weigh-ins.
Michael Rosenbaum, an obesity researcher at Columbia University, summed it up to the New York Times: “The difficulty in keeping weight off reflects biology, not a pathological lack of willpower.” And Michael Schwartz, an obesity and diabetes researcher at the University of Washington, told the Times in a corresponding interview, “You can’t get away from a basic biological reality. As long as you are below your initial weight, your body is going to try to get you back."