Diving Into Protein
When it comes to general protein intake, it’s one of the most important variables when it comes to making improvements to your physique. Protein is the most versatile macronutrient we consume. It can be used to build tissue, broken down to make energy, used as a cofactor in detoxification, or used as an enzyme in metabolism, While all macronutrients require metabolic processing for digestion, absorption, and storage, the thermic effect of protein is roughly double that of carbs/fat. Therefore, eating protein is actually thermogenic and can lead to a higher metabolic rate. This means greater fat loss when dieting and less fat gain during overfeeding/muscle building.
At the basic level proteins are organic molecules made up of amino acids– the building blocks of life. These amino acids are joined together by chemical bonds and then folded in different ways to create three-dimensional structures that are important to our body’s functioning. During digestion, the body breaks down the protein we eat into individual amino acids, which contribute to the pool of amino acids in our plasma. This pool is a storage reserve of amino acids that circulate in the blood. The amino acid pool in the bloodstream readily trades with the amino acids and proteins in our cells, provides a supply of amino acids as needed, and is continuously replenished. Since our bodies need proteins and amino acids to produce important molecules in our body – like enzymes, hormones, neurotransmitters, and antibodies – without an adequate protein intake, our bodies can’t function well at all.
🔹In 2017 the ISSN concluded that the basic recommendation for protein is 0.8-1g/lb of LBM. For people who resistance train, protein requirements can go up to 1.2-1.5g/lb of LBM (1). Switching to a higher protein diet is one of the quickest ways to improve body composition. If you’re not getting a sufficient amount of protein in regularly, you WILL benefit from increasing intake. For some people, .8g/lb may seem pretty high number. However, if you’re currently under that level of intake, you will accrue benefits as you eat more protein.
Muscle protein synthesis (MPS) and muscle protein breakdown (MPB) are the primary mechanisms that regulate muscle tissue growth and loss. MPS is said to build muscle, while MPB does the opposite. The daily net balance of MPS and MPB ultimately determine muscle gains. This is called muscle tissue remodeling, and it responds to stimuli like diet, exercise, and sleep.
The essential amino acids in the protein that are responsible for the increase in ‘muscle protein synthesis’ is in response to total protein quantity and quality. In particular, the amino acid Leucine appears to have an important role as a trigger. It appears to be the most important amino acid, however, all of the essential amino acids are required to serve as building blocks for the building of new muscle.
🔹IN a 2010 publication by @laynenorton it was found that to maximize the MPS, ~2.5g (~0.05g/kg of body weight) of leucine is required (2). This is known as the “leucine threshold” proteins with a higher quantity of Leucine have a larger ability to stimulate and maximize MPS.
If you take something like beef, beef has about 8.6% leucine, so to get 2.5 grams of leucine in beef you’d need about 29 grams of protein and that would require about 183 kcal (“calories”). If you did the same thing with quinoa, it only has about 6% leucine in it. So you need almost 42 grams of protein and quinoa (pretty diluted) you get almost 27 calories per gram of protein. So you need 1100 kcal of quinoa to just get to 2.5 grams of leucine. If we consider that… if you were to consume a meal that contains, let’s say, 20 grams of protein, some of that protein will be coming from plant-based sources (lower in leucine), we don’t know that it would have the same MPS response as a 20-gram bolus of high-quality whey protein rich in lucine.
🔹Dr. Stu Phillips et Al. did an investigation of the impact of protein quality, quantity, and it’s effects on MPS. They found that ~0.045g leucine/kg is sufficient to stimulate/maximize MPS (3).
Practical Ex: Let's take a 200lbs male= ~90.9kg x 0.04 = ~4.09g Leucine/meal to stimulate/maximize MPS.
That would translate to ~40g of whey
~50g of soy protein isolate
~8oz Top Round Beef
~8oz Chicken Breast
To maximize the (MPS) response over the course of a day, it seems that having a protein feeding of at least 30–40g evenly spaced out is sufficient to stimulate/maximize MPS. Quality AND quantity is important! If someone consumes less than that quantity of protein (or a sub-par quality) in a meal the muscle protein synthetic response is going to be sub-maximal, whereas if they consume over that quantity of protein the muscle protein synthetic response isn’t going to be any greater and those amino acids will just be oxidized. When you eat protein is just as important as how much. After resistance training, the body synthesizes proteins for up to 48 hours after training. During and immediately after training, protein breakdown is increased as well. The body actually drops into a short-term wasting or 'catabolic' state... but, consuming enough protein peri-workout can help offset this.
Of all the macronutrients, it seems that timing and distribution (versus simply total daily intake) is most important when it comes to protein.
Take Home Points:
- Muscle protein synthesis is an anabolic response that occurs based on protein feedings and resistance training. For protein, it specifically relates to leucine intake. To maximize the MPS response, ~2.5g of leucine is required. This is known as the “leucine threshold”
- To maximize the MPS response over the course of a day, it seems appropriate to consume 30-40g of protein every 3-4 hours, total meals/day depends on total protein intake.
- A meal that contains 0.4 grams of protein/kg of body weight (I personally like basing protein intake based on lean body mass) (g/kg (BW)) from a high-quality protein source should be sufficient to hit the leucine threshold.
- The best sources of protein is animal proteins (particularly whey protein) due to their high amino acid composition. Plant-based protein sources will mean a higher protein intake is needed to hit the required level of leucine, or becoming strategic about food selection.
- When MPS is “spiked” in response to a protein feeding, it will drop back to baseline within 2–3 hours depending on what that protein source was consumed alongside.
- MPS is only a single variable for muscle hypertrophy, not an exact correlate. Net muscle protein balance (MPS vs. muscle protein breakdown) matters more. And further, there are many other factors that influence actual hypertrophy outside of MPS and MPB.
- Of all the macronutrients, it seems that timing and distribution (versus simply total daily intake) is most important when it comes to protein.