Its not really difficult to see that a specific exercise/training has a completely different affect on the amount of lean mass an athlete carries. You can compare an HIT athlete ie sprinter to a steady state athlete ie marathon runner and see the difference immediately...one builds muscle the other destroys it....no study required. This is irregardless of fuel intake. I would be interested to see a comparison of athletes say in the Boston Marathon or Tour De France who were on keto diets vs carb based diets and how they finished.

P