Circulating levels of the gastric hormone ghrelin rise before and decrease following a meal. In normal weight subjects postprandial suppression of ghrelin is proportional to calories consumed. Obese individuals have lower fasting ghrelin levels, however it is unclear whether the obese show normal postprandial suppression. Postprandial ghrelin response was measured in normal weight insulin-sensitive and obese insulin-resistant subjects, following six test meals with different fat and calorie content (250-3000 kcal).

Increasing the calorie content of meals in normal weight subjects progressively lowered nadir levels of ghrelin. The obese had lower fasting ghrelin levels and the reduction following the consumption of all test meals was less than the normal weight subjects. The lowest postprandial levels in the obese were no different to the nadir in normal weight volunteers following 1000, 2000 and 3000 kcal meals. Circulating ghrelin levels thus decreased in normal weight subjects following mixed meals. Obese subjects demonstrated a much reduced ghrelin postprandial suppression. This reduced suppression may influence satiety thus reinforcing obesity.

This study provides additional insight into the impact ghrelin has on reinforcing obesity – basically, obese individuals may eat more because they don’t feel as full as their non-obese peers.

Source: Diabetes In Control.com: Journal of Clinical Endocrinology & Metabolism 2004, 10.1210.