Dear Doctor: I am 42, female, 5'4" and 182 pounds. I've lost weight on Simmons, Atkins, rice diets, grapefruit, you name it. Why does it always come back? KOC, Chelsea
Dear KOC: Research indicates that 75-95% of people who lose weight gain it all back in months.
In Your Genes?
You come back to your personal set weight through genes interacting with your environment. And yes, KOC, your body actually fights any reduction you make in how much fat you store. The control seems to be in a hormone (leptin) produced by fat cells.
Researchers at Columbia-Presbyterian are finding that leptin works to keep us fat. Weight loss reduces the amount of leptin in the circulation, and lower leptin levels tell the brain to increase food intake to regain the fat.
Earlier studies by Drs. Rudy Leibel and Michael Rosenbaum proved that your body also fights weight loss by making your muscles more efficient at using calories. They showed that if your personal set weight is 150 pounds and you drop down to 135 pounds, you need to eat 250 calories a day less (or exercise 250 calories more) than someone who has always weighed 135 pounds!
As Dr. Rosenbaum puts it, "Whatever lifestyle changes you make to lose weight must be continued indefinitely beyond the period of weight loss if you want to keep the weight off."
Can Leptin Help?
The doctors studied patients who had lost weight and were maintaining their lifestyle changes along with their lower weight level. They gave them leptin and all of them lost more weight. So they concluded that each person has a leptin threshold and when levels fall below your threshold, your brain gets the signal to eat more - -and burn fewer calories - - until you get back to the leptin level that is normal for you.
The doctors' hope is that giving leptin to people trying to maintain a lower weight might trick the brain into thinking that the body has its usual level of fat. Much more research will be required to make that point.
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