I was listening to an episode of the always excellent Sigma nutrition radio, this one an interview with Dr. Donald Layman, who is one of the top researchers in the world studying dietary influences on protein synthesis.
I'm not new to the science on protein synthesis, but if this research is new to you, listen to the podcast, because it's a great overview of the science as we know it today, given by a guy who isn't selling anything (Dr. Layman is an academic, not a supplement salesman), interviewed by a very, very good podcaster in Danny Lennon.
In case you're less of a geek for this stuff than I am, I thought I'd review the key points on what we know regarding protein synthesis.
What is protein synthesis?
Protein synthesis is the process of building new protein in your body. Your tissues in general are not static - your muscles aren't made of the same stuff they were 10 years ago; instead, your body is constantly breaking down and building new tissues. So if not for protein synthesis you would slowly lose muscle mass, or at the very least be unable to gain new muscle.
Why is it important for performance?
If you're any kind of athlete, martial artist or otherwise, you need your muscle. That's what moves you. As you age it gets harder and harder to gain muscle, and to keep the muscle you have, so strategies to grow muscle become more and more important. Almost nobody has too much muscle, and almost everybody who does only gets that way by taking a LOT of drugs that have harmful side effects.
Why is it important for health and longevity?
1. Muscle improves your metabolism, by burning calories and by storing glucose. So having very little muscle will make you prone to accumulating bodyfat. Also, if you have very little muscle and eat a high carbohydrate meal, those carbs have nowhere to 'go' for short term storage, so your blood sugar gets and stays high, and those carbs are turned to fat. If you have lots of excess muscle those carbs can be stored as glycogen to be used in your next workout.
2. Muscle exerts force on your bones. Whenever you move, the bigger and stronger (those are very closely connected) your muscles the more force gets put on your bones, which increases your bone health and strength. Strong dense bones are better at resisting breaks, and broken bones are a huge health risk when you're older.
3. Muscle is key to mobility and independence. If you're not strong enough to get up out of a chair, or carry your luggage around, you lose your ability to be independent. Stay strong, stay out of the nursing home.
What kind of protein is best for increasing protein synthesis?
Protein (all protein) is made up of amino acids. There are different ones (20), and different proteins have different proportions of those amino acids, so the protein in quinoa has a different relative amount of each amino acid as the protein in dairy or beef or eggs or rice.
To get an increase in protein synthesis you need 2 very specific things: 1) 2.2 - 2.5 grams of leucine, a particular amino acid which is relatively high in animal proteins like whey or beef and relatively low in vegetable proteins - this amount acts as a sort of spark to the protein synthesis pathway; and 2) enough of all the essential amino acids so the synthesis can occur. Think of leucine as the guy yelling at the workers to get to work - less than 2.2 or so grams in a meal and the workers don't hear the guy - and the other amino acids as the bricks, without which the workers are trying to work but can't build anything.
Overall, Dr. Layman recommends a meal with at least that much leucine (2.5 g) and somewhere around 50 g total protein. That will kick off a session (my word, not his) of protein synthesis that will last 2-3 hours. He recommends repeating that 3 times per day (more often if you REALLY need to build a lot of muscle, like if you're a competitive bodybuilder). Yes, that's a lot of protein.
As you get older, you get resistant to these cues, so you might need more leucine and/or more protein to get the same response. I imagine the same is true if you have any kind of digestive impairment.
Generally speaking, whey, beef, and eggs are your best bang for the buck for protein that has lots of leucine. Sorry, but vegetable and grain proteins are low in leucine. Getting enough quinoa to spark protein synthesis requires eating just a ridiculous amount of quinoa (think 1000 kCal worth of quinoa in a meal, each meal).
Is muscle protein synthesis really all that matters?
Researchers study muscle protein synthesis because it's relatively easy to study. Give someone a meal, see what happens. But in a way, it's a proxy for what we really care about - long term protein balance. That is, we REALLY care about whether some eating/workout strategy helps us gain (build) net muscle, not whether it results in some short term chemical process.
What exactly do we really care about?
We really care about long term muscle gain or loss. But that's very hard to study - you'd have to control people's meals for weeks or months at a time, and deal with dozens or hundreds of confounding variables. The fact is, if some eating strategy is increasing synthesis but is increasing catabolism (muscle breakdown) even more, you're going to lose.
So there is definitely more to know. I suspect that short fasts decrease catabolism, meaning that you wouldn't necessarily see the best overall muscle mass increase by eating a huge meal every 4 hours, 6 times a day, but that you'd see less synthesis but also less breakdown by eating less often. But I can't prove that, it's just an hypothesis.
What do I REALLY need to know about this research?
1. To gain muscle, you really need to get 40-50 grams of high quality protein in a single meal, and you need to do it probably at least twice a day. Eating 10-15 grams of total protein in each meal, but spreading it out over many meals, is NOT going to get you equivalent results. You can do this by supplementing a normal meal (eat a little, drink a protein shake for dessert) or by eating an animal product heavy meal (this is NOT a huge amount of protein - we're not talking about a pound of steak). If you're not sure whether a particular protein is 'good,' remember to look for the amount of leucine. That's the only amino acid you really need to worry about.
2. DO NOT eat your 50 grams of protein close before your workout. If you spark a session of protein synthesis, that takes a lot of energy. Your muscle cells will be depleted, and you'll be relatively weaker. Try to eat your main meals long before or right after your hard workouts!