Tuesday, May 12, 2015

Study Spotlight: Effects of Diet Composition on Energy Expenditure during Weight-Loss Maintenance

If someone is trying to lose weight there are often a variety of recommended strategies to help them achieve their weight loss goal: eat less, eat low-fat, eat high protein etc. etc. But, what about that person who was able to hit their weight loss goal? What should they be eating???  Researchers out of the New Balance Foundation Obesity Prevention Center set up a study to find out.

What did they do?
The researchers were trying to determine the effects of 3 different dietary strategies on energy expenditure following weight loss. Specifically they were looking at 3 popular macronutrient ratios and glycemic loads on energy expenditure.  All participants in the study participated in a weight loss program that yielded a 10-15% reduction in body weight while consuming a "run-in" diet which consisted of either:

  • Low fat diet (60% of calories from carbs, 20% from protein) which was classified as a high glycemic load.
  • A low-glycemic diet (40% of calories from carbs, 40% from fat and 20% from protein)
  • The same diet (as far as ratios) as the low-glycemic diet but moderate glycemic foods were used.
  • And a very low-carb diet (10% from carbs, 60% from fat and 30% from protein).

All diets were the same in total calorie amount and were followed for a period of 4-weeks.

What did they find?
After a 10-15% reduction in weight loss, those who consumed a low-fat (higher carb) diet experienced the greatest reduction in resting and total daily energy expenditure.  The group that consumed a very low carb diet experienced the smallest reduction in energy expenditure following weight loss even though total calories consumed were the same.

So what does this mean?
Based on the results of the study, following a period of weight loss (or during for that matter), people often experience a reduction in resting & daily energy expenditure. Essentially meaning at the end of the day you burn less calories which moving forward with further weight loss or maintaining that lost weight will be more and more difficult as you will have to further restrict calorie intake or exercise more to maintain that weight loss. However, these decreases in energy expenditure can be mitigated by consuming a diet higher in fat and protein which goes against a lot of people's assumptions when it comes to diet composition.  The added fat and protein help to maintain lean muscle mass which is an active tissue that can help maintain energy expenditure throughout the day. So don't stray away from fat thinking it will help you to lose weight just because it's fat. There is much more to it than that!

Ebbeling CB, Swain JF, Feldman HA, et al. Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance. JAMA. 2012;307(24):2627-2634

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