Therefore, CP673451 in vitro optimal protein intakes 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 during 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 consuming an average protein intake of
2 g/kg. Out of these five, as many as three were in a caloric deficit. The authors 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 consumed 1.6 g/kg of protein with lower carbohydrates. The length of the intervention was only one week, but nonetheless nitrogen losses occurred only in the lower protein 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 SBE-��-CD molecular weight 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 significantly 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 between diets was maintained by reducing dietary fat as opposed to carbohydrate
to allow for the increase in protein. While it appears that the 2.3 g/kg Vitamin B12 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. However, the participants were Selleck Epacadostat 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 degree 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.