Influence of sleep restriction on weight loss outcomes associated with caloric restriction

Abstract

Study objectives: To examine the effects of moderate sleep restriction (SR) on body weight, body composition, and metabolic variables in individuals undergoing caloric restriction (CR).

Methods: Overweight or obese adults were randomized to an 8 week caloric restriction (CR) regimen alone (n = 15) or combined with sleep restriction (CR + SR) (n = 21). All participants were instructed to restrict daily calorie intake to 95 per cent of their measured resting metabolic rate. Participants in the CR + SR group were also instructed to reduce time in bed on five nights and to sleep ad libitum on the other two nights each week.

Results: The CR + SR group reduced sleep by 57 ± 36 min per day during SR days and increased sleep by 59 ± 38 min per day during ad libitum sleep days, resulting in a sleep reduction of 169 ± 75 min per week. The CR and CR + SR groups lost similar amounts of weight, lean mass, and fat mass. However, the proportion of total mass lost as fat was significantly greater (p = 0.016) in the CR group. This proportion was greater than body fat percentage at baseline for the CR (p = 0.0035), but not the CR + SR group. Resting respiratory quotient was reduced (p = 0.033) only in CR, and fasting leptin concentration was reduced only in CR + SR (p = 0.029).

Conclusions: Approximately 1 hr of SR on five nights a week led to less proportion of fat mass loss in individuals undergoing hypocaloric weight loss, despite similar weight loss. SR may adversely affect changes in body composition and "catch-up" sleep may not completely reverse it.

Clinical trial registration: ClinicalTrials.gov (NCT02413866).

Figures

Figure 1.

Participant flow chart

Figure 2.

Panel A. For the CR group, time in bed (TIB) per day averaged over a week at baseline (week 0) and each week during intervention. Panel B. For the CR+SR group, average TIB per day over a week at baseline (week 0) and each week during intervention, as well as average per day during the sleep restricted days and ad libitum days each week during intervention.

Figure 3.

Panel A: The CR group. Total sleep time (TST) per day averaged over a week at baseline (week 0) and each week during intervention. Panel B. The CR+SR group. Average TST per day over a week at baseline (week 0) and each week during intervention, as well as average per day during the sleep restricted days and ad libitum days each week during intervention.