High Protein Diets Don't Counter Anti-Anabolic Effects of Low Energy Intake: 29% Reduction in Free Testosterone, -16% IGF-1 With 40% Energy Deficit Despite 2.4g/kg Protein
|Melt the belly, keep the muscle - a decent amount of protein is key, but more ain't more and as a recent study shows: This has nothing to do with hormones.|
And, last but not least, you will be aware of the fact that the best you can do is to eat enough protein to keep the protein synthetic machinery running by consuming mTOR-promoting fast-absorbing high BCAA (leucine) protein sources such as whey protein (learn more about whey protein).
The fact that protein cannot save your testosterone and IGF-1 levels from plummeting, on the other hand, is something you may only have have gathered based on the data I presented in my March 2013 article about the contest prep of natural bodybuilder Chris Fahs (see "Scientific BB Contest Prep Coverage: Six Months of Dieting, Daily Workouts & Hormonal + Metabolic Shutdown Pave the Natural Way to the Sub 5% Body Fat Zone" | read more). A sufficiently powered study that would determine what Henning et al. call "the anabolic hormonal response to habitual consumption of high protein diets during short-term ED [energy deficit]" as well as the downstream effects of the "modulations in testosterone and IGF-I" on the well-documented preservation of fat free mass "subsequent to consuming high protein diets" (Henning. 2014).
Are effects of protein on IGF-1 and testosterone responsible for the preservation of lean mass
To this ends, Paul C. Henning, Lee M. Margolis, James P. McClung, Andrew J. Young, and Stefan M. Pasiakos (you know him from the dark blue infobox ;-) from the U.S. Army Research Institute of Environmental Medicine recruited 33 adults. The perfectly healthy subjects were assigned to diets providing protein
- 0.8g/kg protein per day (RDA),
- 1.6g/kg protein per day (2X-RDA), and
- 2.4g/kg protein per day (3X-RDA)
Warning, there is a methodological "glitch" here: Actually it's no glitch for us, because we will achieve our "caloric deficit" by the very same combination of working out and eating less as the subjects in the study at hand. Unfortunately, we all know that simple calculations like "run for an hour and eat those three cups of rice less equals 1000kcal" are notoriously unreliable. This does not diminish the overall significance of the study, but I sill want you to keep that in mind, before you overgeneralize the results to "diet only" or "exercise only" scenarios.In view of the previously cited results from Lindy Rossow's natural bodybuilding study (Rossow. 2013; see corresponding SuppVersity article) it's actually not surprising that the scientists hypothesis that "high protein diets would attenuate decrements in testosterone and IGF-I components" is flawed.
|Figure 1: Relative pre vs. post changes in testosterone and IGF-1 & its binding proteins (Henning. 2014)|
This leaves us with an interesting side-finding in the higher protein groups where the changes in fat free mass were directly and negatively (r = − 0.62, P < 0.05) associated with a molecule the scientists call "acid-labile subunit (ALS)". In view of the fact that this protein is also known insulin-like growth factor binding protein this observation provides further evidence for the direct involvement of IGF-1 in the accrual and maintenance of muscle mass.
- Henning, et al. "High protein diets do not attenuate decrements in testosterone and IGF-I
during energy deficit." Metabolism (2014). Accepted Paper - 14. February 2014
- Pasiakos SM, Cao JJ, Margolis LM, Sauter ER, Whigham LD, McClung JP, Rood JC, Carbone JW, Combs GF Jr, Young AJ. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial. FASEB J. 2013 Jun 5. [previous SuppVersity article]
- Rossow LM, Fukuda DH, Fahs CA, Loenneke JP, Stout JR. Natural Bodybuilding Competition Preparation and Recovery: A 12-Month Case Study. Int J Sports Physiol Perform. 2013 Feb 14 [previous SuppVersity article]