Protein improves body composition in women without exercise

Earlier this month I wrote a blog about a study which found that supplementation with protein (whey protein) and the amino acid leucine resulted in increased muscle mass and muscle strength over an 8-week period. I was particularly interested in this because I sometimes recommend whey protein supplementation to individuals looking to maximise muscle gains to be had from resistance exercise.

I came across another study recently that suggests that protein has power to improve body composition in other ways too [1].

In this study, normal weight women (average age 25) were assessed for a number of parameters including the rate at which the burn fat during exercise, body mass, and body fat.

Over the next 3 months, half the study participants had about 480 calories of their normal diet substituted for a protein rich supplement each day. The other half made the same substitution, but with supplements rich in carbohydrate and fat.

At the end of the study period, all of the women were reassessed.

Compared to the women substituting with carbohydrate and fat, those substituting with protein saw:

  • Enhanced fat metabolism during exercise
  • Enhanced fat free mass (weight of body from tissue other than fat such as muscle)
  • Reduced fat mass
  • Reduced body fat percentage

In other words, by replacing some of their usual diet with protein-rich foodstuffs, these women saw improvements in their body composition with (and this is important), no additional exercise. And no conscious restriction of calories either. Sounds like a plan.


1. Soenen S, et al. Protein intake induced an increase in exercise stimulated fat oxidation during stable body weight. Physiol Behav. 2010;101(5):770-4

5 Responses to Protein improves body composition in women without exercise

  1. Lori 24 February 2011 at 11:17 pm #

    This goes along with something I was thinking about this morning. I haven’t lifted weights in over a month. It started with a neck injury; now I’m just being lazy. I haven’t gained any weight, of course, but nor have I lost any according to my scale. And my clothes don’t fit any differently. I know weightlifting has benefits, but now I don’t think it’s a big deal if I miss a workout now and then.

  2. Jane Laine 25 February 2011 at 10:45 pm #

    This isn’t that interesting! If they are substituting protein for their ‘usual food’ which is likely to be more insulin increasing, of course they are going to lose weight. As you say in your book it has nothing to do with calories.

  3. cupcake 25 February 2011 at 10:54 pm #

    I’ve wondered for some time if Hemp protein might suffice instead of Whey? Anyone tried it?
    I’m allergic to milk but would love to boost my ability to burn fat….


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