Gastric Banding Surgery Makes Patients Feel Full

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Dixon AF, Dixon JB, O'Brien PE: Laparoscopic adjustable gastric banding induces prolonged satiety: A randomized blind crossover study. J Clin Endocrinol Metab 90:813-919, 2005.

What is the problem, and what is known about it so far?

When people lose weight, their bodies often fight the change by making adjustments to how they take in and use energy. This is why diets and weight-loss medicines are sometimes not successful in helping people lose weight and keep it off.

But some weight-loss surgeries have been shown to help people lose a lot of weight and keep it off. This might be because these surgeries affect signals in the body that make the body try to use energy the same way it did before the surgery.

Insulin and leptin are two hormones that stimulate hunger and weight gain. Ghrelin is a hormone produced in the stomach that stimulates hunger and weight gain. Weight loss from dieting has been shown to increase ghrelin levels, which makes people feel hungrier. Some scientists think that lower ghrelin levels might be part of the reason that surgical weight-loss procedures are more successful in helping people keep weight off.

One type of weight-loss surgery is called laparoscopic adjustable gastric banding (LAGB). LAGB involves putting an adjustable band around a person's stomach. The band can be adjusted to make the stomach smaller over time.

The researchers wanted to find out how LAGB is able to override a body's hunger hormones in a way that dieting is unable to do. They decided to test the idea that LAGB made people feel fuller for a longer period of time, and that the hormone ghrelin might be involved.

Who was studied?

The study involved 17 people who had LAGB surgery 18 to 36 months before the start of the study. The patients had all lost at least 35% of their body weight and had not had the size of their stomach bands changed within the previous month. The study did not include those who were younger than 18 or those who had a previous weight-loss surgery, type 2 diabetes, or thyroid disease.

A different group of people was individually matched to the LAGB participants based on their body mass index, or BMI (a measure of weight in relation to height).

How was the study done?

Each participant ate a controlled breakfast on two different days. At one breakfast, their gastric bands were adjusted to "optimal restriction." At the other breakfast, their bands were adjusted to "reduced restriction," a slightly larger size than the optimal setting.

They ate breakfast at 6:30 a.m., after not eating anything since 7 p.m. the previous day. The breakfast included cereal, low-fat milk, and banana.

The researchers measured the participants’ height and weight, and sampled blood regularly to measure blood glucose levels and levels of three hormones: insulin, leptin, and ghrelin. Participants wrote down their feelings of fullness every hour and immediately after they ate.

What did the researchers find?

The optimal band size was linked with a lot more feelings of fullness compared with the larger band size, both before and after the meal. LAGB patients with the optimal band size were less hungry than their BMI-matched controls.

Levels of blood glucose, insulin, ghrelin, and leptin did not change between the two band sizes. LAGB subjects had higher ghrelin levels and lower levels of blood glucose, insulin and leptin than the participants who didn't have LAGB.

Insulin, leptin and ghrelin seem to be unrelated to feeling full.

What were the limitations of the study?

More participants and a closer matching of control participants for weight, height, sex, and age might have provided more accurate results.

What are the implications of the study?

"Optimal restriction" of the stomach with LAGB weight-loss surgery makes people feel full for a long time, even when they have not eaten for several hours.

If feeling full is not explained by changes in hormone levels, finding out other ways that LAGB creates a feeling of fullness could help people better understand how the body uses energy and what causes obesity.