SIB #419 - Sleep and Fat Loss

The Study: Insufficient sleep undermines dietary efforts to reduce adiposity 

The Facts:

a. This study is a “Randomized, 2-period, 2-condition crossover study.”

b. They studied 10 overweight adults.

c. There were 3 female and 7 male subjects.

d. They moderately restricted the calories of all subjects for 14 days.

e. The diet was, “caloric content restricted to 90% of their resting metabolic rate.”

f. Also during that time they had them go to bed for either 5.5 or 8.5 hours a night.

g. The subjects did one 14 day period with either the 5.5 or 8.5 hours of bed time along with the calorie restriction.  Approximately 7 months later, subjects repeated the caloric restriction while switched to the other bed time period

h. The actual amount of sleep time was recorded as well since, the subjects did not fall asleep instantly when they went to bed.

i. The authors noted that both bed time durations in conjunction with the calorie restriction resulted in about the same about of weight loss (3kg). But there was a difference in the actual amount of fat loss.

j. The authors found, “…more than half of the weight loss during the 8.5-h time-in-bed condition and only a quarter of the weight loss during the 5.5-h time-in-bed condition was fat…”  In other words, subjects in the 8.5 hr bed time groups lost  roughly twice as much fat.

Take Home:

When the subjects were given more time in bed, which resulted in more time asleep, along with calorie restriction they lost about the same amount of weight but more of the weight they lost was fat.  

Reviewer's Comments:

We’ve reviewed two sleep articles in a row but sleep is important. One of the problems with weight loss is that we generally like it to be as much fat loss as possible. So this study shows that sleep is a factor in how much fat you lose. Now before you leap at me and note that things like resistance exercise can affect the amount of fat loss compared to total weight loss let me say that we might look at some of that in the future but read this study first and dream about it as you count sheep.

Reviewer:  Roger Coleman DC

Editor: Mark R, Payne DC

Reference: Arlet V Nedeltcheva, Jennifer M Kilkus, Jacqueline Imperial et. al. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010 Oct 5;153(7):435-41. doi: 10.7326/0003-4819-153-7-201010050-00006.

Link to Abstract: https://pubmed.ncbi.nlm.nih.gov/20921542/

Link to Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2951287/pdf/nihms236710.pdf