But the high number of body chemicals also means the body has a stiff defense against any attempt to alter how much energy is stored. What's more, said Pennington's Dr. York, when food intake drops, the body's metabolic rate drops too - in part to conserve energy. So a drug that blocks food intake might not have as big an effect on weight loss as anticipated because fewer calories would be burned. Dr. York said he thinks the real advance in appetite-suppressing drugs might come from those that interfere with a set of brain chemicals called opioids. These chemicals give the pleasurable sensation that comes from eating food.
Many people take in extra calories for comfort, or to be sociable - say, at a party.
In any case, preventing or treating weight gain will be difficult, given today's environment and people's biological makeup, Dr. Ravussin said. Most people have little protection against putting on pounds. Those that are protected are the oddballs. This site is best viewed using Netscape 4.0 or IE 4.0.