Slik forbrenner du fett mens du sover

Vekttapet var likt (ca 3kg), men fordelingen mellom hva som var fett og hva som var muskelmasse var dramatisk forskjellig. Gruppa som fikk sine åtte timer søvn hver natt droppet over dobbelt så mye fett (-1,4kg) som gruppa som bare sov fem timer (-0,6kg)!

Styrken ved studien var at den ble utført under kontrollerte forhold og tilmålte mengder mat, men to uker er kort tid og det var kun 10 personer fordelt på to grupper. En eller annen form for trening ville vedlikeholdt muskelmassen bedre.

Søvnmangel kan indirekte føre til vektoppgang fordi det forstyrrer kroppens biorytme og naturlige hormonsvingninger, og man opplever en økt sultfølelse = økt kaloriinntak hvis man ikke passer på litt. Nå ser vi altså at andelen fett/muskler som tapes på diett også har stor sammenheng med hvor mye man sover!

Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity

Annals of Internal Medicine
October 5, 2010 vol. 153 no. 7 435-441

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.

Børge Fagerli,
Coach MyRevolution