Low Calories & Sleep Equals More Muscle Loss & Less Fat Loss

Getting on the bodybuilding stage we want the most muscle and least amount of fat as possible, sleep has a major part in making sure this happen. We are all told how important sleep is, but it seems many still don’t prioritize it. We have busy lives and work comes before all. We diet hard, train hard, and then whatever time we have left we allot for sleep. “Hey what is one less hour of sleep really going to do”? I know so many people that work Monday through Friday and “catch up” on sleep on the weekend. This strategy seems logical, but does it hold up?

Let’s dive into our study for the week.

“Influence of Sleep Restriction on Weight Loss Outcomes Associated with Calorie Restriction”

Purpose: Examine the effect of calorie restriction with or without sleep restriction on body weight and composition.

Subjects: 36 overweight and obese 35-55-year old, untrained.

Protocol: Subjects were randomized to a calorie restriction (95% of RMR) with one group told to reduce there in bedtime during the week by 90 minutes and sleep as much as they want on the weekend. The other group was to continue normal sleep habits.

Results: The sleep restricted group ended up reduce sleep on average by ~1 hour during the week and increased sleep by ~ 1 hour on the weekend. This totaled up to about 75 minutes of less sleep for the entire week. Both groups lost 3.3kgs of body weight over the 8 weeks. The sleep restricted group lost ~32% of weight as body fat and ~68% as lean mass. The normal sleep group lost ~78% of mass as body fat and ~22% as lean mass. The sleep restricted group had a 24% decrease in Leptin levels and 26% increase in Grehlin.

Conclusion: Moderate sleep restriction during the week of 1 hour per night results in less proportion of fat lost and a greater proportion of muscle loss in a calorie deficit. The sleep restriction can increase appetite signaling hormones and make dietary adherence more challenging and weight regain higher.

Take away: Small changes in sleep can greatly impact body composition changes. In a contest prep phase when attempting to retain as much muscle as possible and get shredded lean lack of sleep can greatly detracting from that goal. You can nail your diet and nail training but if you miss on sleep you might be letting your gains fade away and loss prep time from lack of fat loss. Another issue is further increase in appetite stimulating hormones that can make contest prep miserable dreaming about pizza and ice cream all day. Prioritize sleep every night, as catch up sleep does not hold up in regard to body composition in calorie restriction.

What about sleep do you want to know more about, let me know!

John Jewett, MS, RD IFBB Pro

1.         Wang X, Sparks JR, Bowyer KP, Youngstedt SD. Influence of sleep restriction on weight loss outcomes associated with caloric restriction. Sleep. 2018;41(5):10.1093/sleep/zsy027. doi:10.1093/sleep/zsy027