A while back, I shared with you the results of a study looking at different protein feeding patterns. They had one group drink 10g of protein every 1.5 hours. Another group drank 20g every three hours. A third group drank 40g every six hours. All groups drank the same amount of whey protein (80g) over the 12-hour study period. In their experiment, the group that drank 20g every three hours produced the greatest anabolic response.
The results didn’t surprise me because previous studies have shown 20g of whey protein to maximally stimulate protein synthesis. What confused me was the seemingly poor response to 40g of whey. I would have thought 40g would’ve produced a strong anabolic response with blood amino acid levels not returning to baseline for six hours. Part of my confusion may have been caused by the authors of this study suggesting some sort of desensitization to high amino acid levels. This was in line with another theory previously put out by some researchers that there is a “muscle full” effect where despite high levels of amino acids, the cell stops synthesizing muscle protein. This did not bode well for folks like me who consume in excess of 300g of protein per day. Every meal I eat has at least 40g of protein.
Then a group at Rutgers University changed my thinking on the issue of desensitization. They acknowledged that post-meal muscle protein synthesis (MPS) increased rapidly with peak values around 90 minutes and a decline to pre-meal baseline by 180 minutes. The response of muscle tissue was difficult to explain with rapid initiation of MPS associated with increased circulating amino acids, however, the decline in MPS at 180 minutes post-meal occurred with plasma leucine levels still elevated and initiation factors still activated. Everything about the cell and its environment was primed for protein synthesis, but by 180 minutes, everything just stops.
The Rutgers researchers were able to show that the problem lies in the cells’ energy status and a process called elongation. Considering that whole body protein turnover accounts for more than one quarter of resting energy expenditure and that assembling amino acids into protein chains (i.e., elongation) accounts for more than 99% of that energy expenditure, it’s logical that skeletal muscle would shut down protein synthesis to prevent cellular energy depletion.
Not only did this group identify the problem, it also showed that there is a solution, literally. A solution of leucine and/or carbohydrates given between meals is able to restore the energy status of muscle cells and prolong protein synthesis far beyond 180 minutes. So in order to stay anabolic between big meals, prepare a mixture of 5g leucine and 15–30g carbs (e.g., waxy maize) and drink it two hours after your meal. If possible, using BCAAs instead of straight leucine may produce a better effect as BCAAs have been shown to deplete during protein synthesis.