Muscle Diet

I keep hearing that whey protein only lasts for about two hours in your system and that it’s not anti-catabolic. If this is true, how come so many guys use whey? Is casein better?

I've heard and read tons of claims about how quickly whey is digested from “experts” and supplement advertisements over the years. It’s pretty sad, really, because the research on this is clear. I've also heard the “anti-catabolic” (stops muscle breakdown) theory. Okay, let’s do a little myth-busting here:

By far the best research that looked at exactly these topics was done by a group of French protein researchers several years ago. These guys (or monsieurs) meticulously looked at amino acid levels and activity in the blood in research subjects after drinking 30 grams of whey protein versus 43 grams of casein. (They had to give more casein because they wanted to keep levels of the most anabolic amino acid, leucine, equal between the groups, and whey has more leucine.)

Their results show that the whey group experienced higher levels of amino acids in the blood for over three hours. So there’s your first answer. Don’t listen to any of these clowns who say whey is out of your system in one or two hours! This is important because spiking amino acid levels in the blood has been proven to be probably the most important stimulus to muscle building.

More importantly, this resulted in a 68 percent increase in protein synthesis (muscle building) versus 31 percent for casein. The authors described this as a “dramatic” increase in protein synthesis and noted there was no difference in muscle breakdown (catabolism) between the two groups. With the casein, fewer of its amino acids were burned for fuel (oxidized), and it boosted amino acid levels for over seven hours (although it looked like aminos were still being burned at the end of the seven-hour measurement period, so who knows?).

So from these results, you can see that whey is a much better muscle builder over a short or medium time frame and stops muscle breakdown over a three-hour period, whereas if you’re going without food for more than three and a half hours or so, you may be better off with the casein. Keep in mind, though, that the smaller serving of whey and the fact that the subjects hadn't eaten anything for 10 hours would tend to give whey the disadvantage in this study.

Also, studies have proven that the muscle-building process pretty much shuts off after a few hours even if you keep feeding protein, so it’s probably a better idea to use whey to dramatically jack up muscle building in short spurts throughout the day and use casein before bed but only to stop potential catabolism in the early hours of the morning.