However if you actually try to locate an answer to your question you should be able to locate citations that reveal the ingestion of dietary protein beyond roughly 2.0 Gms/kg/day will result in increased Amino acid oxidation, Renal Urea excretion yet NOT result in any improvements in LBM, as compared to ATHLETES ingesting 1.5 to 2gms/kg/day of protein.
So once again contrary to what you may have heard or believe, the often applied bro colloquialism, (that seemingly justifies excesses of almost anything, and everything) MORE IS BETTER is WRONG!
I'm not familiar with any HUMAN studies that involved athletes whom were using AAS and similarly modified their dietary protein intake. However I do suspect they may benefit from even higher protein diets BUT there is obviously a limit bc the overwhelming majority of anabolic pathways are also regulated by feedback mechanisms.
Protein Adequate protein consumption during contest preparation is required to support maintenance of LBM. Athletes require higher protein intakes to support in- creased activity and strength athletes benefit from higher intakes to support growth of LBM [5,22-28]. Some re- searchers suggest these requirements increase further when athletes undergo energy restriction [13,16,22,28-33]. Furthermore, there is evidence that protein requirements are higher for leaner individuals in comparison to those with higher body fat percentages [7,33,34].
The collective agreement among reviewers is that a pro- tein intake of 1.2-2.2 g/kg is sufficient to allow adaptation to training for athletes whom are at or above their energy needs [23-28,35-38]. However, bodybuilders during their contest preparation period typically perform resistance and cardiovascular training, restrict calories and achieve very lean conditions [2-6,17-21]. Each of these factors increases protein requirements and when compounded may further increase protein needs [33]. Therefore, optimal protein in- takes for bodybuilders during contest preparation may be significantly higher than existing recommendations.
In support of this notion, Butterfield et al. [22] found that male athletes running five to 10 miles per day dur- ing a slight caloric deficit were in a significant negative nitrogen balance despite consuming 2 g/kg of protein daily. Celejowa et al. [39] showed that five out of 10 competitive weight lifters achieved a negative nitrogen balance over the course of a training camp while con- suming an average protein intake of 2 g/kg. Out of these five, as many as three were in a caloric deficit. The au- thors concluded that a protein intake of 2–2.2 g/kg under these conditions only allows for a small margin of error before nitrogen losses occur.
Walberg et al. [32] examined the effects of two energy restricted isocaloric diets of differing protein intakes in 19 lean (9.1-16.7% body fat), male, non-competitive body builders. One group consumed a protein intake of 0.8 g/kg and higher carbohydrates, while the other con- sumed 1.6 g/kg of protein with lower carbohydrates. The length of the intervention was only one week, but none- theless nitrogen losses occurred only in the lower pro- tein group and LBM decreased by a mean of 2.7 kg in the 0.8 g/kg protein group and by a mean of 1.4 kg in the 1.6 g/kg protein group. While the high protein group mitigated LBM losses compared to the low protein group, they were not eliminated.
A recent study by Mettler et al. [29] employed the same basic methodology as Walberg et al. [32]. However, one group consumed a protein intake of 1 g/kg, while the other consumed 2.3 g/kg. The high-protein group lost sig- nificantly less LBM (0.3 kg) over the course of the two week intervention compared to the low-protein group (1.6 kg). Unlike Walberg et al. [32] calorie balance be- tween diets was maintained by reducing dietary fat as op- posed to carbohydrate to allow for the increase in protein.
While it appears that the 2.3 g/kg protein intervention in Mettler et al. [29] was superior for maintaining LBM compared to 1.6 g/kg in Walberg et al. [32] a recent study by Pasiakos et al. [40] found a trend towards the opposite. In this study, a non-significant trend of greater LBM retention occurred when subjects consumed 1.6 g/kg of protein compared to 2.4 g/kg of protein. How- ever, the participants were intentionally prescribed low volume, low intensity resistance training "to minimize the potential of an unaccustomed, anabolic stimulus influencing study outcome measures". Thus, the non- anabolic nature of the training may not have increased the participants’ protein requirements to the same de- gree as the participants in Mettler et al. [29] or to what would be expected among competitive bodybuilders.
Maestu et al. [6] did not observe a significant loss of LBM in a group of drug free bodybuilders consuming 2.5-2.6 g/kg of protein during the 11 weeks prior to competition. These results when considered alongside the works by Walberg et al. [32] and Mettler et al. [29] imply that the higher the protein intake, the lower the chance for LBM loss. However, it should be noted that this study did not include a low protein control and not all studies show a linear increase in LBM preservation with increases in protein [40]. Furthermore, two subjects did lose significant amounts of LBM (1.5 kg and 1.8 kg), and the authors noted that these specific bodybuilders were among the leanest of the subjects. These two sub- jects lost the majority of their LBM (approximately 1 kg) during the latter half of the intervention as their per- centage of calories from protein increased from 28% to 32-33% by the end of the study. The group as a whole progressively decreased their calories by reducing all three macronutrients throughout the investigation. Thus, the two subjects uniquely increased their propor- tion of protein, possibly reducing fat and carbohydrate to the point of detriment [6]. That said it is also plaus- ible that the lost LBM seen by these two subjects was necessary in order to achieve their low levels of body fat. It is unknown whether or not the lost LBM influenced their competitive outcome and it is possible that had the competitors not been as lean, they may have retained more LBM but also not have placed as well.
In a review by Phillips and Van Loon [28], it is sug- gested that a protein intake of 1.8-2.7 g/kg for athletes
training in hypocaloric conditions may be optimal. While this is one of the only recommendations existing that targets athletes during caloric restriction, this rec- ommendation is not given with consideration to body- builders performing concurrent endurance and resistance training at very low levels of body fat. However, the re- cently published systematic review by Helms et al. [33] on protein intakes in resistance-trained, lean athletes during caloric restriction suggests a range of 2.3-3.1 g/kg of LBM, which may be more appropriate for bodybuilding. More- over, the authors suggest that the lower the body fat of the individual, the greater the imposed caloric deficit and when the primary goal is to retain LBM, the higher the protein intake (within the range of 2.3-3.1 g/kg of LBM) should be.
http://www.jissn.com/content/pdf/1550-2783-11-20.pdf
