In this article, I am NOT going to discuss why you SHOULD eat protein every 3 hours, but rather, why you SHOULD NOT eat protein less than 3 hours apart.

The real reason why you SHOULD NOT eat protein less than 3 hours apart is because your skeletal muscle tissue becomes insensitive to further stimulation by amino acids, increasing protein oxidation in the liver.

Here’s what this means:

After you intake protein, protein synthesis is increased ~30 mins later and will stay elevated for at least 2 more hours before decreasing back to baseline. However, when we look at Leucine (an amino acid) appearance in our blood, it is still present longer than 2 1/2 hours. Note that these numbers are for whey protein, not casein (milk protein). As seen in this graphic that I used in my previous article, Leucine appearance in whey creates a quick large spike, then proceeds to drop near baseline after around 3 1/2 hours.

These are important to differentiate (protein synthesis vs Leucine appearance) because protein synthesis decreases EVEN WHEN blood amino acid levels are elevated.

When your blood amino acids are still elevated, any amino acids (protein) consumed at this time will just elevate your blood amino acid levels more and have no positive impact of protein synthesis.

This is why you SHOULD NOT intake protein less than 3 hours apart.

When you add amino acids to already elevated blood amino acid levels, it increases urea production (a waste product of protein metabolism). Indicating that the excess amino acids were simply being catabolized in the liver to be excreted in the urine. Now, all of these added amino acids aren’t totally wasted, instead, they just replace proteins that were damaged or oxidized, as I mentioned in a previous article. This means that the protein was simply never utilized by the muscle–so, basically if you ate protein less than 3 hours apart, the protein was worthless in terms of muscle anabolism and stimulation of protein synthesis.

If you are ingesting protein in the fastest digestible form–a whey protein drink–then the earliest you should ingest protein again is 3 hours later. Solid protein foods take longer to digest, so your next meal should be ~4 hours later for optimal protein synthesis stimulation.

In this study, they found greater lean body mass (LBM) gains in 3 versus 6 meals per day–perhaps due to spreading the meals further apart, which led to greater stimulation of protein synthesis when protein was eaten.

Eating less than 3 hours apart could not only be useless in protein synthesis, but could also be detrimental.