Protein Science Just Pivoted, Twice
Two new studies may have you rethinking your post-workout protein protocols.
When I lived down under, the Aussies introduced me to the expression “your bottom is hanging out.” They told me that it means you’ve made a choice that puts you in a vulnerable position, like a bad chess move or paddling for a monster wave that you’re incapable of riding.
Recently, I googled the phrase. It doesn’t exist. My “mates” made it up. This means that not only have I been using a non-existent Aussie-ism for the last two decades, but I’ve also made a Google search the questionable results of which I cannot un-see.
The lesson here is two-fold. First, never trust an Australian. Second, no matter how certain you are of a fact, there’s always a chance that you’re either wrong or could become wrong at any moment.
This holds especially true with sports nutrition. This might be hard to believe given the way so many sports nutrition authorities hammer their points of view as absolute, claiming they’re based on science. Science is the foundation for fact, right?
But science constantly pivots. Sometimes, studies turn out to be flawed. Other times, things are looked at from a new angle that rewrites the rules. A classic example is lactate—or lactic acid, as it’s sometimes called. For ages, experts thought it was the cause of delayed onset muscle soreness (DOMS) until one day science figured out that lactate actually fuels muscles.
On that note, a couple of studies just dropped out of the Maastricht University Medical Centre in the Netherlands that might have you rethinking your stance on protein. The first one questions the upper limit for post-workout protein ingestion. The second one questions the viability of plant-based protein sources.
The one about post-workout protein.
Translation: If you consume a lot of protein after working out, it might keep helping your muscles recover for twelve hours or more.
The post-workout anabolic window theory claims that there’s a timeframe after you exercise when your muscles are especially receptive to protein, so consuming it will help you recover faster. For a long time, the recommendation was 20 grams of protein within 30 minutes of completing exercise. Then, research like this 2013 study in the Journal of the International Society of Sports Nutrition threw those numbers under the bus, claiming that the anabolic window was much longer.
The prevailing wisdom shifted. Nowadays, post-workout protein is still considered beneficial, but not super important. Instead, more experts recommend focusing on eating protein at regular intervals so that whenever your muscles have a chance to repair, you’ll have the amino acid building blocks you need.
Also, that recommended 20-gram intake crept up to 30 or 40 grams. Eat any more than that, and current thinking is that the excess protein oxidizes, meaning you can’t use it for muscle repair.
To clarify a little, when you eat protein, it’s broken down into amino acids that float around in your blood until you use them for, among other things, muscle repair. The big question is how long do amino acids stay in your blood and how many amino acids can you hold onto.
Recently, scientists in the Netherlands discovered that no one has really tested the intake of more than 45 grams of protein for more than 6 hours post-workout—so neither the upper limit nor the time limit are certain. They put this to the test by feeding “36 healthy, recreationally active young men” either zero grams, 25 grams, or 100 grams of milk protein after a whole-body resistance workout and monitored them over the course of 12 hours.
As it turns out, the ones who consumed 100 grams had amino acids in their blood stream available for muscle repair for the full 12 hours. This means they could continue to recover the whole time.
Practical applications.
It’s win-win, really. This study doesn’t discount the current way of doing things. However, it validates intermittent fasting, where people often pile on all their calories in a small timeframe. Basically, it acknowledges that there are multiple ways to do it right.
Just keep in mind that 100 grams is a lot of protein. It’s about three to five protein shakes, or four chicken breasts. From a real-world perspective, we’re talking roughly two fully-loaded Chipotle carne asada burritos.
I see this study as a license to be a little more flexible with your protein intake. Also, it’s a silver lining for those of us who may overdo our Mexican food intake occasionally.
The one about plant-based protein versus a hamburger.
Translation: People absorbed the protein in meals with meat in them better than entirely plant-based meals.
Eight men and eight women between the ages of 65 and 85 were fed a meal with quinoa, chickpeas, soybeans, broad beans, and soy sauce; or a meal with lean ground beef, string beans, potatoes, apple sauce, and herb butter. Calories and protein were matched.
The protein in the meat-based meal promoted muscles building and repair better than the protein of the plant-based meal.
It wasn’t the protein causing the problem. Instead, it was the nutrients surrounding the protein. This is called the “food matrix”—my new favorite terms to use at cocktail parties so I sound smart and worldly, replacing “your bottom is hanging out.”
The food matrix is how all the elements in food interact. It’s rare when you eat a single nutrient. Usually, it’s a mix. An obvious example is how the fiber in fruits like grapefruit and pears cause sugars to absorb slower than those in, say, soda pop.
To this point, the researchers suggested, “Plant-based whole-foods typically contain many antinutritional factors (e.g., dietary fiber, trypsin inhibitors, and phytates) that lower protein digestibility.” In other words, there’s stuff in plant foods that reduce absorption of protein.
Practical applications.
If you’re a vegetarian or vegan, don’t panic. There are a lot of “buts” here. First off, this was a study on older people, who tend not to absorb protein well. Younger people might have absorbed the plant-based protein better. The study authors acknowledged this by writing, “Though we support the concept of moving toward a more plant-based diet for ethical, environmental, and health considerations, there are some concerns with regards to maintaining muscle health later in life.”
Also, you can work around food matrixes by isolating nutrients. In other words, if you’re a vegan athlete, make a point of adding protein powder to your routine—specifically, a “protein isolate” powder that doesn’t have a bunch of other ingredients in it, even good ingredients.
I’m not presenting a couple stone tablets of truth here. Again, science pivots. The results of these studies will probably rewrite the rules a little. Intermittent fasters will glom onto the 100 grams thing. Paleo and keto followers will glom onto the meat thing. But hang on loosely to these new recommendations. Use them as a way to experiment and a reminder not to see nutrition in black and white terms.
Get too dogmatic and the science might pivot again—then you’ll be stuck with your bottom hanging out, mate.
(Props to Dr. Emily Fritz for turning me onto these studies.)
All I read was that the Burrito Challenge is a valid form of training.
Seriously though, it's great to hear you talk about how nutrition, and science in general, keep changing as we learn more and do better experiments. It makes you one of the few people I can trust on this subject.