Lack of Sleep Making You Fat?

image: Roca Zhang

Are you hitting roadblocks in your weight loss and you don’t know why? Doing all the hard work and not getting the results?

A recent study in the American Journal of Endocrinology has determined that women who get less than 7 hours of sleep a night are more inclined to gain weight than other.

The Study

In 1986 (Yes this study was a long one) 68,183 women aged 39–65 years participating in the Nurses’ Health Study responded to a question about sleep duration. At the time of response they were free from disease. Originally they were asked to indicate the total hours of sleep in a 24 hour period. They were sent questionnaires every two years. The most recent questionnaire was in 2002, and the journal article was published late last year.

The Results

From the beginning of the study a clear relationship existed between sleep duration and weight gain. Those sleeping 5 hours or less weight 2.47kg more on average than those sleeping 7 hours. Those sleeping 6 hours were 1.24kg heavier. Remember, this is at the start of the study before any follow up had been done. Not only was there this difference at the start, but the study showed women sleeping less were more inclined to put on weight faster.

Over the 16 years of the study, 10.5% of women experienced a 15kg weight gain. Those sleeping 7-8 hours per night had the lowest risk. Women sleeping 6 hours were 12% more likely to have a 15kg weight gain, and those sleeping 5 hours or less were 32% more likely. It should be noted that calorie intake and activity levels were taken into account in this study and did not affect the percentages.

Why Does Sleep Deprivation Cause Weight Gain?

There are several reasons why a lack of sleep can lead to you gaining unnecessary pounds.

  • Hypothalamic- pituitary functions (a place where your hormones originate from) are strongly linked to circadian rhythms and sleep regulatory processes. These include hormones that influence eating, energy balance and metabolism. So basically a lack of sleep can mess around with some pretty important hormones for maintaining weight.
  • Short term sleep restriction lowers your level of the satiety producing hormone, leptin, which basically makes you feel full. A double whammy to that is that sleep restriction increases levels of the appetite producing hormone, ghrelin. Which makes you basically want to eat more.
  • A side effect of lack of sleep is fatigue. If you are tired you are less inclined to exercise and may reduce physical activity and energy expenditure. Therefore predisposing you to weight gain.
  • It has been suggested lack of sleep can affect your metabolic rate, but further research is needed to confirm this.

So… hit the sack and help your cause, and ask yourself, Are You Sleeping Enough?