Just how important is sleep for weight loss?

Just how important is sleep for weight loss? by Rachel Bartholomew Dip ION MBANT

 

According to a new study recently published in the Annals of Internal Medicine, the definitive answer is VERY!

 

In this latest study to examine the relationship between sleep and weight loss, researchers recruited 10 overweight but otherwise healthy volunteers and studied them over the course of four weeks.  For the first fortnight, study participants were allowed to sleep for up to 8.5 hours, and for the second fortnight their sleep was restricted to just 5.5 hours per night.  Incidentally, over the course of the study, average sleep times for study volunteers was 7 hours 24 minutes for the first two weeks and 5 hours and 14 minutes for the second two weeks.

 

In addition, throughout the course of the study, participants also followed a strict diet of approximately 1450 calories per day.

 

The results were fascinating: the researchers found that there was no difference in total weight loss between the two study periods.  They did find however, that in the first two weeks almost half of the weight lost was from fat compartments, whereas in the second fortnight, when the volunteers’ sleep was restricted, the proportion of fat loss dropped to a fifth of total weight loss with the remainder coming from lean tissue in both cases.

 

Lead researcher, Plamen Penev, assistant professor of medicine at Chicago University commented,

 

“If your goal is to lose fat, skipping sleep is like poking sticks in your bicycle wheels”

 

“Cutting back on sleep, a behaviour that is ubiquitous in modern society, appears to compromise efforts to lose fat through dieting.  In our study it reduced fat loss by 55%”.

So what’s going on?! 
In the study, the researchers discovered that losing sleep boosted production of a hormone called ghrelin; higher levels of ghrelin have been shown to “reduce energy expenditure, stimulate hunger and food intake, promote retention of fat, and increase hepatic glucose production to support the availability of fuel to glucose dependent tissues”.

 

Professor Penev added, “in our experiment, sleep retention was accompanied by a similar pattern of increased hunger and….reduced oxidation of fat”.

 

Interestingly, the authors also proposed the theory that had the sleep-deprived dieters had access to extra food during the day they would have been more likely to act on sharper hunger pangs induced by sleep deprivation, and had this been the case, the differences in fat loss would likely have been even greater.

 

Professor Penev concluded, “people should not ignore the way they sleep when going on a diet”.

Sources:
Arlet, Penev et al. Insufficient sleep undermines dietary efforts to reduce adiposity.  Ann Intern Med October 5, 2010 153: 435-441

Nutri Newsletter, Oct 18th, 2010