Context: Obestatin, a sibling of ghrelin derived from preproghrelin, opposes the ghrelin's effects on food intake. Plasma obestatin profiles in relation to ghrelin have not been fully investigated in human obesity.

Objective: We hypothesize that obesity might present with imbalance of circulating ghrelin and obestatin levels.

Setting: In-patient department of Changhai Hospital, Shanghai, China.

Participants: Sixteen obese (8 men, aged 58.8±4.9; 8 women, aged 59.9±9.6) and fourteen normal weight individuals (7 men, aged 52.7±5.9; 7 women, aged 56.1±4.9).

Main Outcome Measures: Total plasma ghrelin and obestatin levels, one hour before and two hours after breakfast, were measured by radioimmunoassay.

Results: Both preprandial plasma ghrelin levels (P < 0.01) and obestatin levels (P < 0.01) were lower in the obese compared with normal weight controls. However, unexpectedly, the ratio of preprandial ghrelin to obestatin was higher in obese compared with normal weight controls (P < 0.01) even after adjustment for gender and age (P < 0.01). The ratio of postprandial ghrelin to obestatin was decreased both in obese (P < 0.05) and controls (P < 0.01) compared with their preprandial levels. There were no significant differences in the ratio of postprandial ghrelin to obestatin between obese and normal weight controls. BMI was positively correlated with and a significantly independent determinant of the preprandial ghrelin to obestatin ratio.

Conclusion: Circulating preprandial ghrelin to obestatin ratio is elevated in human obesity. We suggest that high preprandial ghrelin to obestatin ratio may be involved in the etiology and pathophysiology of obesity.