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

Abstract

Background: In a previous study, we reported a 4-fold increase in serum leptin following total parenteral nutrition given after surgery. We hypothesised that the perioperative fasting and stress contributed to this, possibly mediated by increased serum insulin and cortisol. Objective: To test the hypothesis that fasting, in combination with glucocorticoids, sensitises the leptin response to subsequent energy intake. Design: Healthy volunteers were randomised into two groups, one group received dexamethasone (DEX), 0.1 mg twice daily for 3 days, while the other group served as a control. Each group was then subdivided into two feeding protocols. Protocol 1, where a standard meal was given at 0, 24, 36 and 48 h and protocol 2 where the same meal was given at 0 and 48 h. Blood samples were drawn before, as well as every other hour during the study period for determination of serum leptin, insulin, glucose and cortisol concentrations. Results: In all groups serum leptin increased significantly following each meal ðP , 0:01Þ: The rise in serum leptin in response to the standard meal was higher when the meal was taken in the evening ðP , 0:001Þ or following longer duration of fasting ðP , 0:02Þ: In those fasting for 48 h, leptin decreased by 60% and showed no diurnal variation. DEX intake increased leptin concentrations in those fasting for short periods ðP , 0:02Þ but not for 48 h. Conclusions: Long durations of fasting sensitise the response of leptin to subsequent energy intake and abolish the DEX-induced upregulation of leptin. Meal timing is an important factor determining the leptin diurnal rhythm, but other factors must contribute since the leptin response to a standard meal taken in the evening was greater than to the same meal taken in the morning.

Decreases in fasting leptin and insulin concentrations after acute energy restriction and subsequent compensation in food intake

“…It has been shown that leptin has a diurnal pattern, which peaks at night (25)(26)(27). Several studies have shown that, during energy restriction, not only fasting leptin concentrations, but also the diurnal variation of these concentrations, is decreased (26,27).…”

“…Several studies have shown that, during energy restriction, not only fasting leptin concentrations, but also the diurnal variation of these concentrations, is decreased (26,27). Additionally, several studies have shown that carbohydrate composition affects the diurnal pattern of leptin.…”

Dissociation between adipose tissue signals, behavior and the food-entrained oscillator

“…Leptin levels in serum show diurnal variations in humans (Sinha et al 1996) and mice (Ahima et al 1998) associated with the dark period and are entrained to mealtime (Elimam & Marcus 2002). The relationship of leptin as a peripheral signal with the main circadian clock, the SCN, was recently explored in vitro.…”

Anorexia, bulimia, and the athletic triad: Evaluation and management

“…Leptin also demonstrates a diurnal pattern of secretion, and levels rise throughout the day and fall at night. Continued fasting results in a delayed rise in leptin [9,10]. Consequently, women with disordered eating and decreased energy consumption have been shown to have lower leptin levels with both lower baseline levels and a blunted diurnal curve [11,12].…”