Lack of sleep and weight – an issue of muscle loss?

October 18, 2010

Many recent studies have looked at the effects of sleep on health, weight, obesity, disease risk, and other outcomes.  Although we don’t yet have definitive data on the topic, it’s fair to say that the evidence is mounting that poor sleep makes weight management even more difficult. Now, a study published last week furthers the data on sleep and weight/weight loss, and suggests that, in particular, lack of sleep during weight loss attempts may lead to increased loss of lean tissue (muscle, bone, etc).  Though the study is preliminary, if true it would signal yet another important reason to consider sleep as an integral part of weight management and disease prevention strategies.   The study is published in the Annals of Internal Medicine here, and the Pubmed abstract is pasted below:

ABSTRACT

BACKGROUND: Sleep loss can modify energy intake and expenditure.

OBJECTIVE: To determine whether sleep restriction attenuates the effect of a reduced-calorie diet on excess adiposity.

DESIGN: Randomized, 2-period, 2-condition crossover study.

SETTING: University clinical research center and sleep laboratory.

PATIENTS: 10 overweight nonsmoking adults (3 women and 7 men) with a mean age of 41 years (SD, 5) and a mean body mass index of 27.4 kg/m² (SD, 2.0).

INTERVENTION: 14 days of moderate caloric restriction with 8.5 or 5.5 hours of nighttime sleep opportunity.

MEASUREMENTS: The primary measure was loss of fat and fat-free body mass. Secondary measures were changes in substrate utilization, energy expenditure, hunger, and 24-hour metabolic hormone concentrations.

RESULTS: Sleep curtailment decreased the proportion of weight lost as fat by 55% (1.4 vs. 0.6 kg with 8.5 vs. 5.5 hours of sleep opportunity, respectively; P = 0.043) and increased the loss of fat-free body mass by 60% (1.5 vs. 2.4 kg; P = 0.002). This was accompanied by markers of enhanced neuroendocrine adaptation to caloric restriction, increased hunger, and a shift in relative substrate utilization toward oxidation of less fat.

LIMITATION: The nature of the study limited its duration and sample size.

CONCLUSION: The amount of human sleep contributes to the maintenance of fat-free body mass at times of decreased energy intake. Lack of sufficient sleep may compromise the efficacy of typical dietary interventions for weight loss and related metabolic risk reduction.

PRIMARY FUNDING SOURCE: National Institutes of Health.

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