Boston, March 8 — Confirming what frus-trated dieters have long feared, researchers at Rockefeller University have discovered that the body’s metabolism compensates for eat-ing less by burning fewer calories.
The finding, published in Thursday’s New England journal of Medicine, explains why most people find it so difficult to’lose weight and keep the weight off unless they perma-nently increase their level of exercise.
It also confirms earlier research into. the long-standing theory that the body’smetabolism has a “set point” that fine-tunes the way the body burns calories.
The researchers found that when a per-son’s weight drops by 10 percent; the body’s metabolic rate falls 15 percent to compensate, thereby burning fewer calories.
Conversely, when most people go on an eating binge and their weight increases by 10 percent, the body compensates by ratcheting up the amount of energy burned by 16 per-cent.
The process seems identical in both obese people and people of average weight.
“These findings offer an explanation for the fact that obese people tend to regain lost weight unless they increase their physical ac-tivity on a permanent basis,’. said Dr. Rudolph Leibel, leader of the team. “It clearly shows that decreasing food intake or increas-ing energy output for a short period is not go-ing to control weight.”
“Good nutrition and increased physical ac-tivity over the long term — are necessary to lose weight and keep it off,” Leibel said.
On average, about 60 percent of the calo-ries a person consumes are used to maintain the body while resting. Another 10 percent are used up digesting food and the remaining 30 percent are burned through physical activity. The findings showing that little difference was seen between obese and non-obese pa– tients “provide additional evidence that obe-sity is a biological disorder, which must be considered in an overall approach: to weight control,” the researcher said.
Losing weight and keeping it off for a long period of time may not be enough to reset the body’s set point ata higher rate, burning more calories, the researchers suggested.
“A reduced level of energy expenditure has-been reported to persist in subjects who have maintained a reduced .body weight fo’ periods ranging from six months to more th’ four years,” they said, citing a 1984 stuck the journal Metabolism.