Weight Loss - Ghrelin & Gastric Bypass
Surgery
Weight Loss Survey Background
Weight loss causes changes in appetite and energy expenditure that promote
weight regain. Ghrelin is a hormone that increases food intake in rodents
and humans. If circulating ghrelin participates in the adaptive response
to weight loss, its levels should rise with dieting. Because ghrelin is
produced primarily by the stomach, weight loss after gastric bypass surgery
may be accompanied by impaired ghrelin secretion.
Weight Loss Survey Methods
Researchers determined the 24-hour plasma ghrelin profiles, body composition,
insulin levels, leptin levels, and insulin sensitivity in 13 obese subjects
before and after a six-month dietary program for weight loss. The 24-hour
ghrelin profiles were also determined in 5 subjects who had lost weight
after gastric bypass and 10 normal-weight controls; 5 of the 13 obese
subjects who participated in the dietary program were matched to the subjects
in the gastric-bypass group and served as obese controls.
Weight Loss Survey Results
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.
Weight Loss Survey Conclusion
The 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. Gastric bypass is associated with markedly
suppressed ghrelin levels, possibly contributing to the weight-reducing
effect of the procedure.
Source: New England Journal of Medicine
2002
David E. Cummings, M.D., David S. Weigle, M.D., R. Scott Frayo, B.S.,
Patricia A. Breen, B.S.N., Marina K. Ma, E. Patchen Dellinger, M.D., and
Jonathan Q. Purnell, M.D.
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