And it seems that people who need fewer calories every day to stay alive may for some reason have a tendency to eat more, Dr. Ravussin said. In the 10-year study, the lower metabolic rate alone didn't account for the weight gained. For people who wonder about their body's calorie needs, doctors have little to offer. Metabolic rates are not easily measured in the doctor's office. Doctors also can't offer much in the way of genetic information.
Scientists do know that a tendency for severe obesity runs in families.
And studies of obese and lean mice have helped pinpoint several human genes involved in body weight. But scientists are still sorting out which genes may make one person more likely to gain weight than the next. We don't have these . . . Only a handful of people worldwide are known to be obese because of a single genetic flaw. More common, doctors say, is a person who has been dealt a genetic hand that contains many small, subtle contributors to the tendency to gain weight.