Another factor that may have played a role in the current investigation is
the type of protein consumed in the high protein group. Because of the difficulty in consuming 4.4 grams of protein per kg body weight daily, every subject in the high protein group acquired their additional protein calories primarily from whey protein powder. It has been shown that the thermic effect is greater with whey versus TGF-beta Smad signaling casein or soy protein . Recently scientists demonstrated that consuming similar calories and protein during resistance training in initially untrained individuals resulted in greater gains in lean body mass in the whey supplemented group versus soy or carbohydrate . Another investigation found that muscle protein synthesis after whey consumption was check details approximately Chk inhibitor 93% greater than casein and approximately 18% greater than soy. Furthermore, the same pattern held when measured post-exercise (whey > soy > casein) . On the other hand, 48 grams of both whey and rice protein isolate consumed post resistance exercise improved indices of body composition and exercise performance similarly . Thus, one might speculate
that if the protein dose or intake is sufficiently high, it may not matter what that particular protein source may be. Conclusion This is the Tangeritin first investigation in resistance-trained individuals which demonstrates that a hypercaloric high protein diet does not contribute to a fat mass gain. Furthermore, there was no change in body weight or lean body mass. This is in contrast with other overfeeding studies which showed gains in body weight, fat mass and
lean body mass; however, those investigations were performed in non exercise-trained individuals that were consuming a lower protein diet (in comparison to our study). It should be noted that the subjects in the current study did not alter their training. It would be intriguing to ascertain if a high protein diet concurrent with a heavy resistance bodybuilding training regimen would affect body composition (i.e. increase lean body mass and lower fat mass). We did not measure blood indices to determine if any side effects (i.e. renal or hepatic function) occurred in the high protein group. A few subjects did complain of gastrointestinal distress as well as feeling ‘hot’ (i.e. their body temperature was chronically elevated). Future research should focus on trained subjects using a single source of protein during overfeeding. Furthermore, a heavy resistance program geared towards skeletal muscle hypertrophy in conjunction with protein overfeeding needs further investigation. Acknowledgement We would like to thank Dr.