Short term response of circulating leptin to feeding and fasting in man: influence of circadian cycle

Abstract

OBJECTIVE: To investigate whether acute feeding induces changes in circulating leptin levels in humans and whether these changes vary according to nycthemeral cycle. METHODS: First experiment. Eighteen male subjects were given a fatty meal at 08.00 h. Blood sampling was performed for 10 h following this meal. Second experiment. Thirteen male subjects were given either a mixed meal or remained fasting either at night (starting at 01.00 h) or during the day (starting at 13.00 h). Blood samples were drawn every hour for a period of 8 h. RESULTS: First experiment. Serum leptin levels increased progressively from a mean (s.d.) baseline of 3.8 AE 2.2 ngaml to a value of 4.5 AE 2.7 ngaml (P`0.01) 8 h after the fatty meal. Second experiment. During the day, serum leptin levels increased progressively from 2.65 AE 1.7 to 3.34 AE 2.2 ngaml (P`0.001) 6 h after the test-meal and decreased from 2.68 AE 1.5 to 1.9 AE 1.1 ngaml (P`0.001) 8 h after the beginning of the fasting experiment. Similar results were obtained at night. No statistically signi®cant differences in leptin levels were observed between day and night sessions in response to feeding (mean area under the curve: 3.0 AE 4.1 vs 4.1 AE 4.1 ngaml) and fasting (72.9 AE 2.2 vs 71.5 AE 2.2 ngaml). CONCLUSION: In two independent experiments, human serum leptin levels increase following food intake. This response is not in¯uenced by nycthemeral cycle.

Meal timing, fasting and glucocorticoids interplay in serum leptin concentrations and diurnal profile

“…An intact hypothalamic-pituitary axis is therefore not essential for the regulation of leptin circadian rhythm. Other groups reported that the diurnal rhythm of leptin is entrained to meal timing and not to the circadian clock (21,37). Our results show that the pattern of food intake affects the diurnal rhythm but does not agree with a complete lack of effect of the circadian clock, as leptin response to the evening meal was higher.…”

The response of leptin, interleukin-6 and fat oxidation to feeding in weight-losing patients with pancreatic cancer

“…Clapham et al (1997) reported no change in leptin concentrations in either adipose tissue or the plasma for 3 h following a mixed meal. Similarly, Dallongeville et al (1998) reported no change up until 6 h following a mixed meal. The results of the present study confirm these findings and would indicate that, in healthy subjects, circulating leptin concentrations are not altered acutely on feeding.…”

Moderate physical activity permits acute coupling between serum leptin and appetite–satiety measures in obese women

“…Circulating catecholamine concentrations are also increased after carbohydrate-rich meals in parallel with serum leptin concentrations, 21,45,46 and a positive association has been found between the elevated circulating leptin and catecholamine concentrations after a carbohydrate-rich diet. 21 Food intake, and predominantly carbohydrate intake, stimulates leptin secretion, 10,12,13,15,21,22 but no association has been found between the increased serum leptin concentrations and the heightened postprandial satiety in the short term (up to 9 h postprandially) in lean or postobese individuals. 21,22 In the context of weight management for obesity, physical activity or exercise alone are better linked with weight maintenance than with enhanced weight reduction.…”

“…[10][11][12][13][14][15][16][17][18][19][20][21][22][23] These studies found no relationship between circulating leptin concentrations and appetite sensations acutely after a meal in normal weight or obese individuals 16,17 or during 20 min food exposure in obese individuals. 18 Serum leptin was found to correlate with appetite sensations only during weight loss or maintenance induced by diet and exercise in obese individuals.…”

“…14,16,19 As such, leptin has been considered as a long-term regulator of appetite during prolonged energy deficits where, presumably, signals increased appetite and food intake to restore fat loss. However, many studies have reported that mixed or carbohydrate-rich meals increase serum leptin concentrations, 10,12,13,15,21,22 indicating that food intake regulates leptin secretion in the short-term. Fasting for 52-72 h has also been found to decrease leptin concentration, while an increase in circulating leptin was reported after overfeeding (12 h) without marked weight changes in normal weight and obese individuals.…”