Friday, March 4, 2011

Research Update: Protein, Glycemic Index, And Maintenance Of Weight Lost

Diets With High Or Low Protein Content And Glycemic Index For Weight Loss Maintenance
Larsen TM, et al.
New England Journal Of Medicine 363:2102-13 2010.

Objective: To examine whether manipulating dietary glycemic index and protein consumption has an impact on maintaining weight loss.

Study Population: 773 men and women from 8 European countries that had lost at least 8% of their body weight on an 800 calorie diet.

Methods:  All participants were put on a low calorie diet prior to the study and had lost 8% of their initial body weight.  After this point they were randomly assigned to one of 5 diets:
1) Low protein (13% of calories) and low glycemic index
2) Low protein (13% of calories) and high glycemic index
3) High protein (25% of calories) and low glycemic index
4) High protein (25% of calories) and high glycemic index
5)  A control diet

The goal of the glycemic index variable was a difference of 15 units of dietary glycemic index.  Subjects were monitored for 26 weeks to see which group was able to keep the weight they lost off.

Results:  1) Subjects who were in the low protein, high glycemic index diet intervention were the only ones to gain a statistically significant amount of their weight back. 2) Subjects in either high protein group regained significantly less weight than subjects in either low protein group. 3) Subjects in either low glycemic group regained significantly less weight than subjects in either high glycemic group.

Take Home Message:  First of all, this was a really tightly designed study that made it into the #1 journal in the world, The New England Journal of Medicine.  That alone says a lot about the methods and overall validity of the study design.

This study shows that if you focus on lower glycemic carbohydrates and add a bit more high quality protein to your diet, you’ll have an easier time maintaining your weight loss.  If you’ve read my book or work with me privately, this is old news to you.  I have seen this for years with my own clients. 

Another really interesting finding is that the investigators also watched the subjects for additional weight loss.  Both the high protein and low glycemic groups were more likely to achieve an additional weight loss of more than 5%.  It appears that in this group of subjects, a higher protein and lower glycemic approach improved both the ability to lose weight and the ability to keep it off.

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