Endocrine Abstracts

Introduction: The chronic reduction of sleep duration is associated to an increased risk of weight gain, but mechanistic aspects remain to be fully elucidated. The aim of our study was to examine the relationship between short sleep duration and energy metabolism, fuel selection and energy balance in overweight and obesity. Methods: Inclusion criteria were: age 18–65 years, BMI ≥25 kg/m². Use of any CNS medications, any psychiatric disorders and night shift work were considered as exclusion criteria. Body composition was evaluated by DXA. All participants underwent indirect calorimetry. The respiratory quotient (RQ) was calculated from gas exchanges. The equations by Weir and by Frayn were used to calculate the resting energy expenditure (REE), and carbohydrate and fat oxidation, respectively. Sleep duration, total daily energy expenditure (TDEE) and the level of physical activity (METs/day) were objectively assessed (Sensewear Armband). A 3-day dietary record was administered. Participants were divided into two groups, “regular sleep” (RS): >300 min/day or “short sleep”(SS): ≤300 min/day. Results: 88 women and 30 men were included (age:49.6±12.1 years), of whom 30.5% exhibited a short sleep duration. BMI (39.7±7.1 vs. 36.2±5.0 kg/m², P=0.03) and truncal body fat (18.7±6.2 vs. 16.1±4.6 kg, P=0.04) were higher in the SS group than the RS group. Subjects with short sleep had a lower RQ (0.71±0.12 vs. 0.76±0.12, P=0.004) and oxidized more fat (113±55 vs. 95±56 g/min, P=0.006) than regular sleepers. The METs/day were higher in the SS group compared to the RS group (1.56±0.55 vs. 1.35±1.24, P=0.04). RQ was positively associated to sleep duration (P=0.04, adj. for age, sex, and body fat). No difference emerged in TDEE or energy intake (SS group: 23±10 vs. RS group: 25±6 kcal/kg/day, P>0.05).

Conclusion: Short sleep affects energy substrate metabolism and adiposity distribution in overweight and obese subjects.