CBS News Correspondent Mark Phillips reports researchers at London's Imperial College School of Medicine believe they may have found an answer. They are conducting a study in which hormones are injected that have the effect of telling the would-be slimmer patients that they are not hungry.
"I ate some of it, then I'd had enough, just didn't want anymore," recalls test subject Andre Hugo.
The hormone is the one the body naturally produces to let the brain know when it's had enough and to stop eating. Overweight people, in fact, may be deficient in producing it.
In Hugo's test group, some of the eaters were given injections of the hormone while others were given a salt solution. The ones given the hormone ate 30 percent less.
"Half the problem is overweight people are not getting the proper signal to their brain, saying they've just eaten a large meal, so they still feel hungry and carry on eating," explains researcher Dr. Rachel Batterham
The hormone therapy is only in an experimental stage, and there are drawbacks – the main one being that it has to be injected. There's no magic pill.
"We've been trying telling patients to eat less, take more exercise, for hundreds of years – and it really is proving ineffective. In fact, obesity is getting commoner and commoner with each decade," said researcher Dr. Steve Bloom. "We have to do something. Is this the answer? I think part of the answer."
The stop-eating hormone could be a major weapon in the war against obesity, but a more efficient way would have to be found to get it into people's bodies - instead of food.