Sleep is one of the most neglected aspects of health for most athletes. Not getting a good night’s sleep can not only affect performance, it can also impact your progress in the gym. Studies on volunteers who slept short versus long hours show that sleep reduction was accompanied by increased hunger, higher circulating concentrations of the appetite-stimulating hormone, ghrelin, and reduced concentrations of the anorexigenic hormone, leptin.

The Study

To determine whether sleep loss attenuates the effects of a reduced-calorie diet on excess adiposity, researchers had subjects follow a similar diet but differed the duration of sleep. One group slept 8 1⁄2 hours per night while the other group slept 5 1⁄2 hours. Sleep curtailment decreased the fraction of weight lost of fat by 55% and increased the loss of fat-free body mass by 60%.

Reduced Loss of Body Fat

In summary, dieting adults getting 5 1⁄2 hours of sleep produced a catabolic state characterized by reduced loss of body fat and increased loss of fat-free body mass, accompanied by increased hunger and changes in energy expenditure and the neuroendocrine control of substrate utilization.

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Sleep is one of the most neglected aspects of dieting. Missing out on sleep may not only make you tired but will blunt your fat loss. The findings should make athletes aware that cutting back on sleep while dieting can not only cause a catabolic state but can also hinder fat-loss gains.

Increased Risk of Weight Gain

In this month’s prestigious journal of Obesity, researchers reported that sleep loss can result in reduced metabolic rate. Short sleep duration is a significant risk factor for weight gain. Researchers wanted to examine the impact of losing sleep and its effect on metabolism. Healthy adults participated in a controlled laboratory study. After two baseline sleep nights, subjects were randomized to an experimental:

  • 4 hours of sleep per night for five nights and one night with 12 h recovery sleep)
  • 10 hours of sleep per night (control condition)

Resting metabolic rate and respiratory quotient were measured using indirect calorimetry in the morning after overnight fasting. Resting metabolic rate—the largest component of energy expenditure—decreased after sleep restriction (−2.6%) and returned to baseline levels after recovery sleep. Sleep restriction decreased morning resting metabolic rate in healthy adults, suggesting that sleep loss leads to metabolic changes aimed at conserving energy.

Andrea M. Spaeth, David F. Dinges, and Namni Goel. Resting metabolic rate varies by race
and by sleep duration. Obesity. Volume 23, Issue 12, pages 2349–2356, December 2015

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