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.

If you are no newbie to the SuppVersity you will be aware that there is no way to escape the "anti-anabolic" effects of suboptimal energy intakes. You will also know that protein catabolism cannot be countered by the ingestion of extra protein (see "Protein Intake & Muscle Catabolism: Fasting Gnaws on Your Muscle Tissue and Abundance Causes Wastefulness" | read more).

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 data from the Pasiokos study shows: 1.6g/kg and not 2.4g/kg allows for the optimal balance of fat loss and lean mass retention (Pasiakos. 2013)

I guess, I have to warn you again! More protein is not a solution - even if some gurus want to make you believe it was. While the study at hand will only confirm that it does not help, a previous study by Pasiakos et al. (2013) revealed that eating too much protein (in this case 3x the RDA, i.e. 2.4g/kg) and thus necessarily too few carbohydrates and fats (learn more in " Evidence From the Metabolic Ward: 1.6-2.4g/kg Protein Turn Short Term Weight Loss Intervention into a Fat Loss Diet" | go back)

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)

for 31 days. The testosterone, sex-hormone binding globulin (SHBG) and IGF-I levels of the 20-22-year old men were assessed after a 10-day period of weight-maintenance (WM) and after 21 days of consuming a calorically reduced (-40%) diet.

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)

The testosterone and IGF-1 levels of the volunteers who resided on the metabolic ward at the USDA Grand Forks Human Nutrition Research Center to ensure experimental control, plummeted and the acid-labile subunit decreased (Note: The ostensibly high decrease in total testosterone in the 1xRA is a result of surprisingly high total testosterone levels 668.9ng/dL after the accommodation phase on the 1xRDA diet). This alone is not exactly what you would call "muscle preserving". In conjunction with the concomitant increases in the respective binding proteins, i.e. SHBG and all three IGF binding proteins (P < 0.05), the short (21 day) diet phase led to an utter deterioration of two important components of what I would like to the "anabolic milieu" that's necessary for optimal skeletal hypertrophy.

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.

It takes some profound changes in T-levels to see real-world effects on lean and/or fat mass | learn more

Bottom line: Protein helps, but it's effect are non-hormonal and mediated via the activation of the p-AKT/mTOR protein synthetic cascade. Put simply: A higher protein intake can help you keep the protein synthetic machinery running. In conjunction with exercise (s. red box), the unquestionably the most powerful anti-catabolic, a higher protein intake helps to preserve lean mass on a diet. What (additional) protein cannot do, though is to ameliorate the diet-induced reductions in testosterone and IGF-1 that occur, whenever you consume significantly less energy than you need.

Whether you consider it surprising or even unbelievable or simply natural that this doesn't mean that you will "fall apart", is probably a matter of how deeply rooted your (from a science perspective) unwarranted believe in the effects of reductions / increases in testosterone within the normal range is (with 420ng/dL even the men in the 3xRDA group who had the lowest T-levels were still "in range"). If you've read my previous dissertations in "Quantifiying the Big T" (read more), you shouldn't be all too surprised, though (suggested read: "IGF-1 and its Splice Variants MGF, IGF-IEa & Co - Master Regulators or a Bunch of Cogs in the Wheel of Muscle Hypertrophy?" | more).

References:

• 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]