Here we are. It’s 2018, and yet we still don’t have everything pegged down with regards to the optimal amount of protein to maximize recovery, repair, and adaptations to training. We were told we had it all figured out years ago, yet most of what we were told as fact was much closer to assumption and extrapolation. So before I tell you that this is the most definitive, cutting-edge, space age answer to one of the most important nutrition and training related questions, I’d first like to remind everyone that we still don’t have all the bases covered. Most of the research into this specific question deals only with lean tissue maintenance, hypertrophy, or changes in body fat. The amount of research in this area looking directly at the effects of protein absorption on true athletic performance is basically non-existent.
So we have to borrow what we can from changes in body composition and muscle protein synthesis and hope there is crossover into the sports realm. The data we have is better than nothing, and we’re heading in the right direction with meta-analyses and reviews of the literature becoming more and more effective at giving us the most practical and important pieces to this incredibly complex puzzle that is human physiology. The most recent, and useful, piece of the puzzle comes to us from Alan Aragon and Brad Schoenfeld in their review of the longitudinal findings of research looking specifically at the amount of protein per meal to maximize muscle protein synthesis (MPS) and the implications of these findings on total daily protein intake and distribution throughout the day.
The first thing we should do is establish what is meant by protein absorption. This is a very confusing topic because the term is used to mean many different things. For our purposes, protein absorption is the amount of protein that can be ingested and effectively utilized to stimulate the synthesis of new muscle protein. This gets confusing when people don’t explain whether they are referring to either:
- Acute protein absorption (how much can be effectively utilized in one sitting)
- Daily total protein absorption (how much can be effectively utilized in a 24 hour period).
The data is pretty clear that whey protein, for example, when ingested by itself, has an acute protein absorption rate of about 10 grams per hour. If you ingest 30 grams of whey protein, it will take approximately 3 hours before this bolus of protein is broken down into its individual amino acids and therefore made available for anabolic processes.
Whey is a very fast-acting protein, so amino acid levels in the blood spike very quickly after ingesting whey. This may be a very good thing when it comes to the training window, but may not lend itself to maximal efficiency when it comes to maximizing net protein synthesis versus net protein breakdown. After all, what good is maximizing muscle protein synthesis right now if you aren’t getting enough protein in throughout the day to counteract the entire protein breakdown that occurs that day? This is where things begin to get a little tricky. We have to step back from our current position and evaluate what the best level of analysis will be. The hard question to answer is now this: Is it better to maximize the anabolic effects of protein at the level of a meal, or at the level of a 24-hour day?
Maximizing Max Protein Synthesis per meal OR Maximize Max Protein Synthesis per day?
These two often-competing ideas both have their pro’s and con’s, as well as data to support their basic presuppositions. The first camp, often called the “muscle full” concept, views the practical aspects of protein absorption research from the level of the meal. The basic idea is that the amount of protein that can be effectively used to maximize muscle protein synthesis in one sitting is about 20-25 grams of high quality protein. Perhaps this level of analysis brings the focus too close to the question, and therefore leaves us with a need to eat this amount of protein every 2-3 hours through the course of the entire time one is awake in order to maximize the muscle full effects. Though effective, this is quite unpractical.
The idea on the other end of the spectrum is to determine the total amount of protein necessary to maximize muscle protein synthesis in a full day. This area of research is getting more attention as Intermittent Fasting gains more popularity. The general idea is to hit your daily protein goal (typically about 2.2 grams of protein per kilogram of body weight per day, or 1 gram of protein per pound of body weight per day) in any way that you can within a 24-hour day. Proponents of this type site data showing that the timing of ingestion may be less important than ensuring you are getting enough protein in the day to match and exceed the amount of protein breakdown that occurs. Perhaps this level of analysis brings the focus too far from the ideal question, since it leaves open the option to get all of ones’ protein in 1 or 2 meals. The research on this is very weak in the area of sport performance and hypertrophy, but does show that this type of protein ingestion (all in 1-2 meals) does work equally effectively at maintaining lean tissue mass in comparison to other protein feeding timing structures (source). The research in this area usually includes studies using less than ideal protein consumption and few studies include a resistance-training component. So if both of these have their pro’s and con’s, how do we get the best of both worlds?
This is specifically where Aragon and Schoenfeld deliver and show their quality. They explain that both of these ways at looking at protein absorption and utilization are not mutually exclusive, and therefore the most effective way to maximize MPS, currently, is by first getting enough protein per meal to maximize acute MPS (we’ll get to how much this is in the next paragraph). This acute goal (hitting minimum protein per meal) is then placed into the realm of the daily protein goal so that the athlete gets maximal stimulation of new muscle protein at specific times of the day, but also maximal stimulation of new muscle protein for the full day. From a practical perspective, most athletes simply cannot eat a meal every 2-3 hours. For most athletes, therefore, the most practical nutrient timing and distribution plan is 4 meals per day, or 3 meals and a pre- or post-workout snack or mini-meal.
Hitting the acute protein goal is most effectively accomplished by ingesting at least .4 grams of protein per kilogram of body weight per meal. This means that someone who weighs 200 lbs (200/2.2 = 90.9 kgs) would need to get at least 36 grams of protein per meal (.4 x 90.9 = 36.36). Since the daily minimum of protein ingestion to maximize net protein synthesis is 1.6 grams of protein per kilogram of body weight per day, this athlete needs to ingest at least 145 grams of protein per day (90.9 x 1.6 = 145.44). This equates to 4 meals per day of 36 grams of protein per meal. This is actually quite easy to accomplish, but remember, this is on the low end of the spectrum. For this athlete to ensure they are really maximizing acute and daily protein absorption and utilization, they should shoot for somewhere between .4 and .6 grams of protein per kilogram of body weight per meal and 2.2 grams of protein per kilogram of body weight per day. Using .55 grams of protein per kilogram of body weight per meal gives us 200 grams of protein for the day to maximize MPS for a 24 hours period and 50 grams of protein per meal, spread into 4 meals.
There you have it, folks. Based on what we can glean from current and previous research, the best way to understand and get the most out of the rate of protein absorption is to place an equal amount of emphasis on the two different levels of analysis, and follow one while not neglecting the other. Both are necessary to maximize muscle protein synthesis, and therefore maximize your recovery from training, repair from muscle damage, and adaptations to training specific variables like speed, power, strength, and reaction time. I think the best way to pay tribute to this quest of answering the protein absorption question is to let the researchers conclude things in their own words. Aragon and Schoenfeld state:
“It is therefore a relatively simple and elegant solution to consume protein at a target intake of 0.4 g/kg/meal across a minimum of four meals in order to reach a minimum of 1.6 g/kg/day – if indeed the primary goal is to build muscle. Using the upper CI (confidence interval) daily intake of 2.2 g/kg/day over the same four meals would necessitate a maximum of 0.55 g/kg/meal. This tactic would apply what is currently known to maximize acute anabolic responses as well as chronic anabolic adaptations.”
About Kevin Kuhn
Kevin Kuhn, M.S.Ed., CSCS, MFS is a Kinesiologist and Sport Nutrition Coach in Dallas, Texas. Before moving to Dallas in 2012, Kevin was the head strength & conditioning coach for the Indiana Invaders professional running club in Indianapolis, Indiana. Kevin specializes in athletic performance with great interest and experience in running-specific strength & conditioning, corrective exercise, and exercise and sport nutrition. Kevin has been certified by the National Strength & Conditioning Association as a Certified Strength and Conditioning Specialist (CSCS) and as a Master Fitness Specialist by the Cooper Institute.
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