this peice of INFO, found at another GREAT site with free info on LEANGAINS.com, its about intermittent fasting although, but so far free till his book is written at least im guessing. has significant relevance to the protein powder digestion rates that people may find interesting. Worth reading! also check out his site since it does have a ton of different studies on subjects that shed light on many bodybuilding assumptions on dieting etc.
http://www.leangains.com/2010/10/top-ten-fasting-myths-debunked.htmlMyth: Maintain a steady supply of amino acids by eating protein every 2-3 hours. The body can only absorb 30 grams of protein in one sitting.
Truth
Whenever you hear something really crazy you need to ask yourself if it makes sense from an evolutionary perspective. It's a great way to quickly determine if something may be valid or if it's more likely a steaming pile of horseshit. This myth is a great example of the latter. Do you think we would be here today if our bodies could only make use of 30 grams of protein per meal?
The simple truth is that more protein just takes a longer time to digest and be utilized. For some concrete numbers, digestion of a standard meal is still incomplete after five hours. Amino acids are still being released into your bloodstream and absorbed into muscles. You are still "anabolic." This is a fairly standard "Average Joe"-meal: 600 kcal, 75 g carbs, 37 g protein and 17 g fat. Best of all? This was after eating pizza, a refined food that should be quickly absorbed relatively speaking.
Think about this for a second. How long do you think a big steak, with double the protein intake of the above example, and a big pile of veggies would last you? More than 10 hours, that's for sure. Meal composition plays an important role in absorption speed, especially when it comes to amino acids. Type of protein, fiber, carbohydrates and prior meals eaten all affect how long you'll have amino acids released and being taken up by tissues after meals.
Origin
I think this "30 grams of protein"-nonsense started to circulate after a classic study from 1997 by Boirie and colleagues. "Slow and fast dietary proteins differently modulate postprandial protein accretion" was the first study to quantify the absorption rate of whey and casein protein and gave birth to the concept of fast and slow protein. After that, whey protein came to be known for it's ability to rapidly elevate amino acids in the blood stream and casein for it's ability to create a sustained release of amino acids. Whey was anabolic and casein anti-catabolic.
Given that 30 grams of whey protein was absorbed within 3-4 hours, I guess some people believed that meant 30 grams of protein can only be used in one sitting. Or that you had to eat every 3-4 hours to stay "anabolic." Unfortunately, people missed a few facts that made these findings irrelevant to real-world scenarios. First of all, this study looked at the absorption rate of whey protein in the fasted state. On it's own, and with no meals eaten beforehand, 30 grams of whey protein is absorbed within a mere 3-4 hours. With meals eaten earlier in the day, or if you'd consume a whey shake after a meal, absorption would be much slower.
Second of all, whey protein is the fastest protein of all and digests at 10 g/hour. Casein is much slower; in Boirie's study, the casein protein was still being absorbed when they stopped the experiment 7 hours later. Most whole food proteins are absorbed at a rate of 3-6 grams an hour. Add other macronutrients to that and they'll take longer.
One of my clients, showing symptoms of profound catabolism by impaired protein absorption and daily 16 hour periods of fasting.
Further reading:
"Is There a Limit to how Much Protein the Body can Use in a Single Meal?" by Alan Aragon.
What Are Good Sources of Protein? – Speed of Digestion Part 1
What Are Good Sources of Protein? – Speed of Digestion Part 2