Regulation of average 24 h human plasma leptin level; the influence of exercise and physiological changes in energy balance

OBJECTIVE: The effects of short-term moderate physiological changes in ener gy flux and energy balance, by exercise and over- or underfeeding, on a 24 h plasma leptin profile, were investigated. DESIGN: Subjects were studied over 24 h in four randomized conditions: no e xercise/energy balance (energy intake (EI)=energy expenditure (EE)=11.8+/-0 .8 MJ); exercise/energy balance (EI=EE=15.1+/-0.6 MJ); exercise/negative en ergy balance (EI=11.8 +/- 0.8 MJ, EE=15.1+/-0.8 MJ); exercise/positive ener gy balance (EI=18.6+/-0.7 MJ, EE=15.1 +/-0.6 MJ). SUBJECTS: Eight healthy, lean men (age: 23.5+/-7.0 y, body fat 14.1+/-5.4%, body mass index (BMI): 2 1.4+/-2.3 kg/m(2)). MEASUREMENTS: Blood was sampled every hour during the daytime (09.00-23.00 h) and every two hours during the night (01.00-09.00 h) for analysis of pla sma leptin, insulin, glucose, FFA and catecholamines. RESULTS: Plasma leptin levels were highest around 01.00 h (mean+/-s.e.m. 4. 9+/-2.0 ng/ml) and lowest around 11.00 h. (2.3+/-0.7 ng/ml). An increased 2 4 h EE, induced by exercise under conditions of energy balance, significant ly decreased the peak and average 24h plasma leptin concentration. A positi ve energy balance, by overfeeding, resulted in a significantly higher ampli tude of the 24h plasma leptin curve, compared to a condition of energy bala nce. CONCLUSION: Exercise decreases peak and average 24h plasma leptin concentra tion and a moderately positive energy balance increases the amplitude of th e 24 h plasma leptin profile. These effects are not acute, but are manifest within 24h. The variations of average 24h FFA and average 24h glucose conc entrations almost fully explained the variation in average 24 h leptin conc entration across trials.