Weight-loss news that's easy to stomach. University Diet & Nutrition Letter v14, n2 (April, 1996):1 (1 pages).COPYRIGHT Tufts University Diet and Nutrition Letter 1996

Ever hear talk about how the stomach shrinks after a person has been dieting, resulting in less hunger than previously? Well, the stomach - a grapefruit-sized organ when empty - can't really get any smaller. But new research shows it does lose its capacity to stretch as much as it did when it was accustomed to holding more food. And that makes a dieter feel full on less.

Investigators at Columbia University's Obesity Research Center proved the point when they measured the holding capacity of 14 obese people's stomachs both before and after putting them on a weight-loss regimen. To make the measurements, the researchers threaded balloons into the subjects' stomachs through their mouths and throats and gradually filled them with water. After each two-fifths of a cup, the men and women rated their feelings of fullness, nausea, and abdominal bloating on a scale of 1 to 10, with 10 being the worst. When a participant rated discomfort at 10, the balloon filling stopped.

Before beginning the diet, the men and women, who weighed on the order of 220 pounds, could hold an average of almost four cups of water in their stomachs.Four weeks later, when they had lost anywhere from 12 to 28 pounds, their average holding capacity before they reached 10 on the discomfort scale was less than three cups - a decline in stomach capacity of 27 percent.

A second test in the same subjects relied not on their subjective responses but instead used a machine to measure the pressure exerted on the stomach wall with increasing amounts of water. In this test, stomach capacity went down by 36 percent In fact, after four weeks of dieting, the women could no longer hold any more volume in their stomachs than a group of normal-weight women observed in a separate study.

The researchers hypothesize that it is not obesity per se that increases stomach capacity but overeating. Specifically, the problem appears to be eating large individual meals rather than eating too many calories over the course of the day. Consider that normal-weight bulimics, who sometimes eat thousands of calories at a time during binges, have even greater stomach capacity than obese people of the same age.

A larger stomach capacity not only makes it easier to eat larger meals; it also apparently increases the desire for them. The researchers point out that the stomach has special "stretching sensors" responsible for sending signals to the brain to induce satiety. But they believe the sensors may not get the signals going until the stomach has been distended to a certain proportion of its capacity. Therefore, the more the stomach can hold, the larger the meal needed to inform the brain that a person is full.

Fortunately, the converse appears to be true as well. The less food the stomach becomes used to holding comfortably, the less it takes to inform the brain that the body has had enough to eat. That's good news for dieters.

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