Sleep restriction causes increases in body weight and abdominal fat
Effects of Experimental Sleep Restriction on Energy Intake, Energy Expenditure, and Visceral Obesity
Introduction and methods
Chronic sleep deprivation has been associated with obesity, morbidity and premature mortality, However, studies on this association have shown conflicting results [1-4]. Observational data implicating that short sleep duration contributes to obesity, while strongly suggestive, are inferential [5-10]. Experimental studies on sleep restriction and weight regulation are limited and contradictory [11-16]. Furthermore, it is unclear whether sleep deprivation induces fat gain, and where in the body excess fat is stored [17-20].
Aim of the study
The aim of this randomized, controlled, crossover study was to investigate the effects of extended sleep restriction versus normal sleep (control) on energy intake, energy expenditure and regional fat storage in healthy, non-obese participants. During the study, participants had unlimited and free access to food.
A total of 12 healthy individuals (9 men/3 women aged between 19-39 years) with body mass index (BMI) < 30 kg/m2 participated. Participants spent 21 days in the study facility. They were randomized 1:1 to 14 days of experimental sleep restriction (4 hour sleep opportunity) or control sleep (9 hour of sleep opportunity). Prior to these 14 days, all participants spent 4 days acclimatizing during which they were able to sleep for 9 hours. The 14 days of sleep restriction or control sleep were followed by 3 days of recovery time. After a 3-month washout period, participants spent another 21 days in the study facility with those who had been subject to sleep restriction in the first cycle now undergoing control sleep and vice versa. As before, the cycles started with 4 days of acclimatization and ended with 3 days of recovery time.
The primary outcome of this study was mean change in daily calorie intake between acclimation and experimental phases which was assessed as the difference between sleep restriction and control conditions. Secondary outcomes included resting and post-prandial energy expenditure, body weight and abdominal fat distribution (measured by CT scan).
- During sleep restriction, participants consumed an extra 308.1 calories per day (95% CI 59.2-556.8 kcal/day, P = 0.015), with higher protein and fat intake (10.9 grams/day, P = 0.050 and 13.5 grams/day; P = 0.046, respectively).
- There was no change in energy expenditure between the periods with and without sleep restriction.
- Body weight increased during both the sleep restriction period and the control sleep period but was greater after the sleep restriction (+0.5 kg, 95% CI 0.1-0.8 kg, P = 0.008).
- The total amount of abdominal visceral fat increased significantly during experimental sleep restriction, compared with control sleep (between-condition difference of 7.8 cm² , 95% CI 0.3-15.3 cm², P=0.042)
The researchers concluded that 14 days of sleep restriction in the setting of unlimited access to free food results in an increased energy intake which – in the absence of changes in energy expenditure – leads to significant weight gain.
The authors wrote: “Our findings provide the first causal evidence for the epidemiologic observations linking short sleep to abdominal obesity and to visceral fat.”