Effect of environmental temperature on appetite, energy intake and appetite-regulating hormones during rest

There is evidence to suggest that the exercise-induced suppression in appetite is more pronounced when exercise is performed in the heat compared with colder environments. Whether such effects of environmental temperature are seen at rest remains unknown. The aim of this study was to examine the effect of environmental temperature on energy intake (EI), appetite and appetite-regulating hormones during rest. Nine men (aged 21.4 ±1.3 years) rested for 5.5-hours in three conditions i) a thermoneutral environment (20˚C), ii) a hot environment (30˚C) and iii) a cold environment (10˚C). After baseline measures, each participant was supplied with a standardised breakfast meal containing 6 kcal·kg body mass-1. Further blood samples were collected at 0.5, 1, 1.5, 2, 3, 4, 5 and 5.5 h during the postprandial period, with an ad libitum pasta meal provided at 4-4.5 h to measure EI. Perceptions of appetite were assessed using 100-mm visual analogue scales every 30 min. Blood samples were analysed for gut hormone concentrations. Significant effects of condition for ad libitum EI (P = 0.002) were found; EI was higher in 10˚C and 20˚C compared with 30˚C. The findings of the present study support the limited evidence that environmental temperatures may modulate EI.