If you fill your stomach with a gel-like substance that swells so much that very little room is left for food, will you lose weight? Researchers at Gelesis, a Boston-based company, think so. They have been testing a polymer or hydrogel called Attiva. The substance is about the size of a sugar grain but when the grains are consumed in a capsule along with water, the grains swell into a gel- like substance. As the gel expands in the stomach, little room is left for food. The gel also stretches the stomach walls and stimulates nerve fibers that tell the brain the stomach is too full to receive any more food. Rats given this gel stopped eating for about 18 hours. Early tests with humans produced a sensation of fullness after meals and a decrease in hunger between meals. But these particles did more than limit food intake. When they finally leave the stomach (by shrinking and going back to their granular form) they enter the small intestine where digested food is absorbed into the bloodstream. Here they swell again and trap digested sugar and fatty acids in their viscous matrix. Think of partially firm Jell-O with bits of fruit floating around in it. The polymer is the Jell-O-like substance that captures bits of sugar and fatty acids. Eventually, as the polymer shrinks again, the sugar and fatty acids are released and slowly trickle into the blood stream. The gel continues on its way through the large intestine, finally disintegrates, and passes out of the body. Might this be the answer to our ever-increasing problem with obesity? The polymer has one major advantage over appetite-suppressant drugs. Since it never enters the blood stream, side effects are probably much less than those associated with weight-loss drugs. Its advantage over surgical methods to reduce the size of the stomach is obvious, as it eliminates the risks of an operation. But will it really have an impact on obesity? It certainly will stop someone from consuming an excessive amount of food. If the stomach has room for only one small hamburger, rather than a triple cheeseburger with bacon, a large order of fries and a 20-ounce container of soda, many fewer calories will be consumed. People who binge may be particularly receptive to the weight- loss substance, as the tiny stomach capacity will abort quickly any episode of excessive food intake. Of course, unlike the surgical procedures used for stomach-size reduction that are in place, Attiva must be swallowed before eating. One can imagine a scenario in which someone goes on a cruise and decides to skip the gel for a week because he wants to get his moneyâs worth from the meals on board. (Iâve seen this happen with people using the nicotine patch who remove it when they want to smoke.) Surgical methods to reduce stomach size have been around for decades. Still, it is not understand why many people who have had these procedures rarely attain their weight-loss goals and why others gain back weight despite the tiny size of their stomachs. Some people are so driven to eat that they often risk vomiting or injuring their stomach because they swallow too much food. Obviously, they are not eating because they feel physically hungry. Hunger goes away very quickly after the surgical procedure. So why are they still eating more than they should? It is likely that the triggers that made them overeat excessively before the surgery are still influencing their food intake. The reasons for their overeating reside in the brain, along with their emotional state, work, social, family situations, hormones, and lack of sleep. Can Attiva stop overeating caused by medications such as antidepressants, premenstrual syndrome, overwork or simply boredom? Somehow it seems unlikely that a woman with PMS searching for chocolate will settle for the hydrogel instead. Perhaps the best we can hope for is that gel will allow her to settle for six chocolate kisses rather than a pound of fudge.