Is permanent, significant weight loss really possible?
If you're talking merely 10 to 20 pounds - and nobody knows the actual figure - you probably can diet and exercise your way to a svelter self and stay there, provided you stick with your weight control program rigorously. Forever.
But if you're among the two-thirds of adult Americans who are overweight or obese, permanent, substantial weight loss appears to be almost impossible by diet and exercise alone.
Only about 1 to 2 percent of obese people can permanently lose weight through diet and exercise alone, said Dr. Lee Kaplan , director of the weight center at Massachusetts General Hospital.
"Dieting is like holding your breath," he said. "You can do it, but not for long. Your body is stronger than your willpower."
In other words, Americans have probably wasted way too much time, money, and hope on diet programs that don't help enough. It still makes sense, however, to eat as healthily as you can and to do whatever you can to avoid gaining any more weight.
One famous study conducted at the University of Minnesota during World War II illustrates the ineffectiveness of severe dieting. The researchers put 36 physically and emotionally healthy young men of normal weight on a strict diet, allowing them only half the calories they were used to. The men lost weight, but became psychological wrecks, obsessing about food, bingeing, and, even after the diet was over, eating way too much, often 8,000 to 10,000 calories a day until they regained the weight, recounted
In another classic study in the 1950s, researchers at Rockefeller University in New York City recruited obese people who were so desperate to lose weight that they agreed to live in the hospital for eight months, including a four-month period in which they subsisted on only 600 calories a day of liquid formula. They lost weight, Kolata noted. But, to the dismay of subjects and researchers, they all quickly regained the weight.
That's because the basic biochemistry of the body's weight management system can work against even highly motivated dieters.
When a very fat person loses a lot of weight by diet and exercise, the brain goes into panic mode, reading a complex array of chemical signals as proof of impending starvation. Metabolism slows. The body hangs on to every calorie it can get. The chemical signals that trigger appetite soar, creating a drive to eat so powerful you can't resist. From the standpoint of evolution, this makes sense: Our DNA was built when we were hunter-gatherers to protect us against starvation, not obesity.
