Why was this study done?

The role of hormones (insulin, testosterone, growth hormone) in muscle building is fairly well established. What is less understood is the role of macronutrients (protein, carbohydrate, fats) and their impact on those hormones. This study was designed to help understand the importance of post-exercise supplementation for anabolic hormone production. Participants were supplemented with either protein, carbohydrate, or a combination of the two following exercise.

What did the study find?

Carbohydrate alone and carbohydrate with protein had the most stimulating effects on insulin production. The combination of carbohydrate and protein has the best effect on growth hormone six hours after exercise. Testosterone was decreased by all supplementation, but appears to be the result of increased excretion.

Dietary supplements affect the anabolic hormones after weight-training exercise.
Authors: Chandler RM, Byrne HK, Patterson JG, Ivy JL. J Appl Physiol (1985). 1994 Feb;76(2):839-45.
PubMed Citation PMID: 8175597.
PDF Manuscript: J Appl Physiol, 1994.