I've been wondering for a while where protein to build muscle comes from?

If I consume protein throughout the day and that protein is pretty much digested and processed within an hour or two of consumption. But most muscle building happens while at rest, how does the protein I consumed at 5:00pm make it to bed time?

2 Answers 2


Not all the protein is digested.

But without enough, the body will feed on itself during the night. This is why athletes, bodybuilders, etc. eat slow-digesting protein (e.g., casein) at bedtime--to provide a sustained protein store.

  • I'm currently consuming casein before I go to bed. But it seems I may need to consume an extra shake before bedtime.
    – Salsero69
    Commented Jun 13, 2012 at 23:12
  • @Salsero69 Why do you believe that? Commented Jun 13, 2012 at 23:12
  • This theory that having some hard-to-digest protein in the gut while sleeping helps with muscle building is something I have never heard of. Is there any research indicating that it's true?
    – J. Win.
    Commented Jun 14, 2012 at 7:37
  • @DaveNewton proteins have to be «digested» (broken down into amino acids) by enzyme protease before it can be used to build muscle. Commented Jun 14, 2012 at 9:18
  • 1
    That's an interesting study. So if that pans out I might eat some protein before going to bed too :) But it has to be said: It's a study with 16 people which is preliminary at best. Especially since the increased muscle growth only was on the fringes of statistical significance. So that study doesn't tell you much except that further studies might be a good idea. Commented Jun 15, 2012 at 6:31

About 1% of all amino acids (which proteins are made of) in your body are in free form. For example inside the cells or in the blood. So that pool can be used for muscle building.

But you also should not forget that muscle building is a pretty slow process and it's not like all your muscle growth will happen at night. So the amount of protein needed for that won't be that much. Especially compared to the amount of protein needed for other purposes.

Proteins basically run the whole body. Or they are the whole body. The immune system, all enzymes, structural proteins, hormones (e.g. insulin) etc.etc. So you can safely assume that the body has a "storage space" for amino acids like he has for glucose and fat.

So as a normal, healthy person I wouldn't worry too much about getting a protein deficit only because you don't eat protein for half a day.

  • This really depends on a person's goals, activity level, etc. I wouldn't give the same advice to an athlete concerned with peak performance that I'd give to a desk jockey. Commented Jun 14, 2012 at 22:19
  • That's why I wrote normal :). An athlete concerned with peak performance hopefully has better resources and or knowledge than some forum on the internet can provide. A specialized MD for example. Commented Jun 14, 2012 at 22:31
  • 2
    some of us are desk jockeys concerned with peak performance ;)
    – J. Win.
    Commented Jun 16, 2012 at 2:24

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