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Impaired Ghrelin Secretion May Aid In Weight Loss

Surgery may alter the capacity of the stomach to generate afferent signals to the brain, including secretion of ghrelin, a hormone that increases food intake in humans and rodents.

This is one possibility raised by a study of plasma ghrelin levels after diet-induced weight loss or gastric bypass surgery done by researchers at the University of Washington and other centres in Seattle, Washington, and Portland, Oregon, United States.

In normal subjects, ghrelin levels increase before meals and decrease after meals. Among patients in this study who achieved stable weight after gastric bypass surgery, circulating ghrelin levels were low and did not show meal-related periodicity.

An increase in the plasma ghrelin level with diet-induced weight loss is consistent with the hypothesis that ghrelin has a role in the long-term regulation of body weight.

David E. Cummings and colleagues hypothesized that because ghrelin is produced primarily by the stomach, weight loss after gastric bypass surgery may be accompanied by impaired ghrelin secretion.

The researchers determined 24-hour plasma ghrelin profiles, body composition, insulin levels, leptin levels and insulin sensitivity in 13 obese subjects both before and after a six-month dietary weight loss program.

These 24-hour ghrelin profiles were also determined in five people who had lost weight after gastric bypass and in 10 normal-weight controls.

Five of the 13 obese subjects in the dietary program were matched to the subjects in the gastric-bypass group and served as obese controls.

Plasma ghrelin levels rose sharply shortly before and fell shortly after every meal. A diet-induced weight loss of 17 percent of initial body weight was associated with a 24 percent increase in the area under the curve for the 24-hour ghrelin profile.

In contrast, despite a 36 percent weight loss after gastric bypass, the area under the curve for the ghrelin profile in the gastric-bypass group was 77 percent lower than in normal-weight controls and 72 percent lower than in matched obese controls.

The normal, meal-related fluctuations and diurnal rhythm of the ghrelin level were absent after gastric bypass.
N Engl J Med 2002;346:1623-1630. "Plasma Ghrelin Levels after Diet-Induced Weight Loss or Gastric Bypass Surgery"

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