Resting metabolic rate varies by race and by sleep duration

Abstract

Objective Short sleep duration is a significant risk factor for weight gain, particularly in African Americans and men. Increased caloric intake underlies this relationship but it remains unclear whether decreased energy expenditure is a contributory factor. The current study assessed the impact of sleep restriction and recovery sleep on energy expenditure in African American and Caucasian men and women. Methods Healthy adults participated in a controlled laboratory study. After two baseline sleep nights, subjects were randomized to an experimental (n=36; 4h sleep/night for 5 nights followed by 1 night 12h recovery sleep) or control condition (n=11; 10h sleep/night). Resting metabolic rate and respiratory quotient were measured using indirect calorimetry in the morning after overnight fasting. Results Resting metabolic rate—the largest component of energy expenditure—decreased after sleep restriction (−2.6%, p=0.032) and returned to baseline levels after recovery sleep. No changes in resting metabolic rate were observed in control subjects. Relative to Caucasians (n=14), African Americans (n=22) exhibited comparable daily caloric intake but a lower resting metabolic rate (p=0.043) and higher respiratory quotient (p=0.013) regardless of sleep duration. Conclusions Sleep restriction decreased morning resting metabolic rate in healthy adults, suggesting that sleep loss leads to metabolic changes aimed at conserving energy.

Phenotypic Stability of Energy Balance Responses to Experimental Total Sleep Deprivation and Sleep Restriction in Healthy Adults

“…Our results are in concordance with prior studies showing marked gender differences in energy intake with sleep loss [1,10,21]. In this study, daily caloric intake was also more stable in men, consistent with our prior findings [20].…”

“…Separate studies of sleep restriction [1,2,3,21,22] and total sleep deprivation [16] have demonstrated energy balance responses to sleep loss return to baseline levels after one or more nights of recovery sleep. Whether this recovery and its time course is similar following sleep restriction and total sleep deprivation remains unknown.…”

“…During sleep restriction, men exhibit lower subjective ratings of fullness [5] and greater increases in caloric intake [1,10,21], consume more calories during late-night hours [10], and gain more weight than women [1,2]. Furthermore, these energy balance responses are more stable across repeated exposures to sleep restriction in men than women [20].…”

Association of gene coding variation and resting metabolic rate in a multi-ethnic sample of children and adults

“…Generally, RMR is lower in women than in men, and in older adults compared to younger adults, and is mainly dependent on the amount of muscle mass (and other metabolic tissues) [2]. Other variables impacting RMR include sleep duration [3], physical activity [4], and obesity [1, 5, 6]. As the amount of metabolic body tissue is strongly related to RMR, RMR per total body mass is reduced in obese individuals compared to normal weight individuals, due to their larger proportion of fat mass relative to the total body mass [2].…”

Response to: “Can Racial Differences in Resting Metabolic Rate be Explained by Body Composition?”

“…TO THE EDITOR: We are writing in response to the letter related to our original article "Resting Metabolic Rate Varies by Race and by Sleep Deprivation" (1). We appreciate that Avila et al found our work to be of high interest.…”