Research has shown that the timing of protein intake can have a significant effect on your gains. In short, you want amino acid levels to peak in your bloodstream when blood flow and nutrient uptake in muscle tissue are maximized. Blood flow and nutrient uptake in muscle tissue are at their highest during your workout, when you’re feeling the muscle pump. Sounds simple enough, right? Well, it’d be a lot simpler if all protein foods were digested and absorbed at the same rate. In other words, it’s hard to time “peak amino acid levels” if you don’t know how long your last protein meal takes to peak.

Whey and casein are two of the most popular protein powders, and countless studies have analyzed how long amino acids take to peak after a dose of each. Whey is particularly quick-peaking, taking 40–60 minutes and returning to baseline by 120 minutes. Casein is far slower and has a less-pronounced peak, with amino levels staying elevated for nearly four hours after casein ingestion. But what about actual protein foods such as eggs, beef, or milk? Information about their absorption rates could benefit anybody planning their meals. 

A study conducted at the Australian Institute of Sport measured how long it took for amino acid levels to peak after ingestion of several protein foods. They looked at skim milk, soy milk, eggs, beef, and a liquid meal replacement drink with a 1:1:1 ratio of whey, casein, and soy. They looked at time to peak total amino acids (TAA), essential amino acids (EAA), leucine, and branched chain amino acid (BCAA).

They found significant differences in the time it took amino acids to peak in the bloodstream. Skim milk stood out as the fastest protein to produce peak amino acid levels in all categories. Similar to whey, skim milk caused a rapid increase and a rapid decline in amino acid levels. Beef and egg stood out as keeping amino acid levels elevated well into the two-to- three-hour range. Eggs were particularly good at keeping BCAAs elevated above all others, reaching the two-hour mark. 

With these results we know that protein meals based on skim milk and/or whey protein need to be taken 30 minutes before or immediately after training. On the other hand, protein meals containing eggs or beef should be saved for the last meal of the day, allowing blood amino-acid levels to stay elevated for hours into the night. Taking in the right protein at the right time will go a long way toward maximizing your gains. – FLEX