Monday, July 1, 2013

Short on Sleep May Mean More Calories – and Weight Gain

     Over the past several years, the evidence that points to lack of sleep as a contributing factor to overeating has increased. In a 2010 study, researchers put 10 overweight participants on a moderately low calorie diet and then let them sleep up to either 8.5 hours or 5.5 hours for two weeks. They then switched participants to the other sleep group for another two weeks. They measured weight and body composition (fat vs. muscle) after each two period.  
Here’s what they found:
  • More Sleep, More Fat Loss. When people got more sleep, they lost more of their weight as fat (3 pounds vs. 1.3 pounds) and less of their weight as muscle (3 pounds vs. 5 pounds).
  • Less Sleep, Higher Hunger. When people got less sleep, they were hungrier. Their levels of a hormone called ghrelin were higher than when they were allowed to sleep longer. Ghrelin is a hormone in the stomach that makes you hungry.

      A study published last year in the Annals of Internal Medicine gives us a clue as to how a lack of sleep contributes to insulin resistance – which can lead to obesity and heart disease. The researchers found that when people were sleep deprived, their fat cells ability to respond to insulin dropped by about 30%. 
      But both of these studies were very small and inconclusive. Now a study published in this month’s edition of the journal Sleep, adds to the data. And this was a big study – 225 people. In this study, the researchers found that the people who were allowed only four hours of sleep over 5 consecutive days ate 500 calories above their needs a day and gained about 2 pound over the following 9 days. The people who were not sleep deprived did not eat extra calories above their needs nor did they gain any weight.  This was a short-term study so we cannot say whether these changes would remain over the long haul.
      Now, getting more sleep alone is not going to make you fit into your bikini in time for summer vacation. For one thing, not everyone is sleep deprived and not everyone who is sleep deprived overeats as a result. But lack of sleep could be contributing to America’s weight problem. The Centers for Disease Control reports that over 20% of Americans are getting 6 or fewer hours of sleep a night – well below the seven to nine we need.
So here are some tips to get the best sleep:
  • Stay Calm Before Sleep: avoid caffeine, alcohol, troubling reading, and over stimulating, violent TV at bedtime
  • Avoid Energizing Activities Before Bed: avoid exercise and bright lights around bedtime; try dim lights, meditative thoughts, and warm milk (yuck!).  A warm bath right before bed can help with sleep. Computers and cell phones seem to stimulate brain activity so avoid them before bed!
  • Set the Stage: make sure your bedroom has curtains that are heavy and keep your room dark.
  • Make Sleep a Priority:  just like you make time for your family, exercise, and eating, making the time to sleep should be just as important.

Now if only we could find a way to add more hours to the day!

Beth Kitchin PhD RDN
Assistant Professor, Department of Nutrition Sciences
University of Alabama at Birmingham

Sources:
Nedeltcheva AV et al. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153:435-441.

Broussard JL, Ehrmann DA, Van Cauter E, Tasali E & Brady MJ. Impaired insulin signaling in human adipocytes after experimental  sleep restriction: a randomized, crossover study. 2012; 549-557.

Spaeth AM, Dinges DF & Goel N. Effects of experimental sleep restriction on weight gain, caloric intake, and meal timing in healthy adults. Sleep. 2013

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