Well I was wrong -- there is a magic hormone

March 5, 2003

Passed on to me from the other list (you may note the small number of subjects

in the study, and the 6-month duration of the study):

From the New England Journal of Medicine...

Plasma Ghrelin Levels after Diet-Induced Weight Loss or Gastric Bypass Surgery

E. Cummings, M.D., S. Weigle, M.D., R. Frayo, B.S.,

A. Breen, B.S.N., Marina K. Ma, E. Patchen Dellinger, M.D., and Q.

Purnell, M.D.

ABSTRACT

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.

Methods

We 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.

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 (P=0.006). 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

(P<0.001) and 72 percent lower than in matched obese controls (P=0.01). The

normal, meal-related fluctuations and diurnal rhythm of the ghrelin level were

absent after gastric bypass.

Conclusions

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.

March 5, 2003