Gastric bypass surgery: Why some don’t lose as much

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Gastric bypass surgery is practically a sure bet for losing a great amount of weight, plus benefiting from the extras that come with it: a better quality of life, less risk for related illnesses like heart disease, and a longer life.

But not everyone who undergoes the surgery, in which the stomach is surgically shrunk, allowing less food to be eaten, has tremendous success. A new study may have found two factors that those people have in common: diabetes, and a larger stomach pouch.

Researchers at the UC San Francisco examined data from 310 people who had undergone the surgery and had a starting body mass index of 52 (a BMI of 40 or more is considered morbidly obese). After a 12-month follow-up, the participants lost an average of 60% of excess body weight, and had an average BMI of 34. However, 38 people (12.3%) were in the poor weight-loss category, losing less than 40% of excess body weight. Results were published in the September issue of the journal Archives of Surgery.

The researchers adjusted for a number of factors that included age, sex, race and insurance status, and found that diabetes and a larger pouch were linked to the smaller weight loss.

Bypass surgery has been shown to cure diabetes or decrease symptoms in some who undergo the surgery. But those who take insulin could be at a disadvantage, according to the study, since it may promote fat and cholesterol production. Those with the disease may also need to eat more when experiencing low blood sugar episodes, leading to weight gain. Tweaking medication, the researchers suggest, could encourage shedding more pounds.

Pouch size seems to be important as well, and size can vary according to surgeon. The bigger the pouch, the more food it can hold. The authors write that ‘most surgeons estimate the pouch size solely on anatomical landmarks,’ rather than a sizing balloon, and call for a more standardized approach.

-- Jeannine Stein