Protein: Quantity, Quality & Timing,

Lets talk all things protein. We’ll keep it pretty simple to start. The protein you eat provides amino acids which are used for building new tissue, repairing old tissue, and many other cellular functions. Bodily proteins are made from 20 different amino acids. 9 of these are called “essential amino acids” (EAAs) because your body can’t synthesize them, so they must be obtained through the diet.

QUANTITY

The current RDA of protein is 0.8 grams / kg of bodyweight (0.36g/lb). These recommendations come from outdated studies observing relatively inactive adults, and the amount of protein intake needed to maintain nitrogen balance. But these recommendations don’t apply to anyone who wants to optimize their muscle mass and strength while living an active lifestyle. Individuals looking to promote skeletal muscle growth and strength should consume upwards of 1-1.2 grams per pound of bodyweight per day.

When you exercise, you damage your muscles and need amino acids to repair, rebuild and recover. If your protein intake is insufficient, your body will break down muscle tissue over time to increase circulating amino acids, which will be used for other processes instead of maintaining muscle mass. Adequate protein intake provides all the amino acids needed for muscle repair and all other bodily functions served by amino acids. A good starting goal if you know you don’t eat your bodyweight in protein each day? Consciously aim to eat more protein at each meal.

TIMING

While total quantity of protein is what you should focus on first, protein timing does have implications on muscle growth too. Say you weight 150lbs, and aim to consume 150 grams of protein each day. Doing so in 2 meals would be difficult, each having 75 grams of protein. That’s almost a pound of meat each meal. It also likely wouldn’t keep you in an anabolic (growth promoting) state for as long throughout the day.

Optimizing protein intake timing to increase time spent in muscle-protein synthesis (MPS) will likely contribute to greater gains. You are always in a state of MPS or muscle protein breakdown (MPB). MPS is stimulated by resistance training, but also by protein ingestion. Of the EAAs, leucine seems to be the trigger for MPS. The duration of MPS and leucine needed to initiate it likely vary depending on an individuals muscle mass. Most studies show 2.5-4g of leucine (found in 25-40g animal based protein) will initiate MPS. MPS will remain elevated for 2-3 hours, or all day, depending on the quantity and quality of the protein ingested, as well as the amount of other macronutrients ingested with it.

For example. Post workout, you consume a 30 gram Whey isolate protein shake. Whey isolate is a rapidly absorbed protein, which will give you a quick rise in circulating leucine, triggering MPS. But, that elevation will likely be more rapid in onset but shorter in duration compared to consuming a protein shake with whey, casein, and some fruit. Casein is a slower absorbed protein, fiber in fruit slows down digestion, so the onset of MPS would likely be more gradual but last for longer.

Therefore, it seems reasonable to assume that consuming a meal with at least 30 grams of protein 3-5 times a day will keep MPS elevated for majority of the day. This is where intermittent fasting can get in the way of optimal muscle growth. If you must intermittent fast, consider adding in a simple 30g protein meal within an hour of waking (ex. protein shake, 25g egg whites + cheese, 1.5 cups non-fat Greek yogurt, 4oz cooked meat) while abiding to your feeding window as you normally would.

Training Considerations

If you are evenly distributing your protein over 3-5 meals each day, you’ll have enough circulating amino acids to build muscle and recover. The post workout “anabolic window” has been disproven, and you don’t NEED to get protein in immediately post workout. But, for many, post workout is an easy time for them to get a protein shake in, contributing to their total daily goal.

If you’re training fasted, first thing in the morning, protein intake post workout is important. MPS is stimulated by exercise, but MPB is also at its highest following an overnight fast. Both are elevated, but MPB will prevail unless you ingest some amino acids. Eating protein and carbohydrates after training first thing in the morning will give you the amino acids to recover and stimulate MPS, but also stimulate insulin release from carb ingestion, which inhibits muscle protein breakdown.

*Although eating protein more frequently may be beneficial, eating too little per sitting is counterproductive. Eating 15g of protein in a sitting won’t give your body the same anabolic response as 25g. The amino acids contained in that 15g won’t hit the MPS threshold, and they’ll likely be oxidized for energy or other bodily repair.

QUALITY

Protein quality is characterized by the EAA content and their digestibility, or what percentage of the protein is actually absorbed. Animal proteins are higher quality because they have higher amounts and bioavailability of all EAAs. Plant proteins typically have low amounts of a few EAAs, lysine and methionine being the most common. If your intake of an EAA is too low, deamination and oxidation of other amino acids will occur. Rice and beans are a common meal in vegetarian diets, likely because grains are low in lysine and beans are low in methionine, so pairing the two provides all necessary EAAs in sufficient quantity. Plant proteins are usually lower in leucine than animal proteins, so total daily intake would have to be increased by about 15-30% if consuming a plant based diet to account for the necessary amount of leucine to keep MPS elevated.

The Digestible Indispensable Amino Acid Score (DIASS) is an index measuring protein quality, examining EAA content and bioavailability. Plant proteins tend to score lower on this index than animal proteins. When plants are consumed in whole food form, their other nutrients (like fiber) make the digestion and absorption of amino acids more difficult. For every 10 grams of protein from whole chickpeas (DIASS = 83) you consume, you’re only absorbing about 75% of that 10 grams of protein. Amino acid absorption from whey, eggs or egg whites is nearly 100%.

Some proteins are absorbed faster than others. Therefore, they can have different implications on MPS rates and duration. Whey protein, milk, eggs, egg whites, and other isolate protein supplements will be absorbed quickly, spiking MPS but maybe not keeping it elevated for long. Casein, a slower digesting form of protein powder, is slow to breakdown and release amino acids into the bloodstream. Whole food protein, like chicken breast, takes longer to digest and provides a consistent stream of amino acids for longer. Therefore, it helps to mix up your protein sources, and consume mixed macronutrient meals.

TAKEAWAYS

• Aim for 1 gram protein / lb of bodyweight if you want to maintain or increase muscle mass over time

• Consume 3-5 meals with relatively equal amounts of protein to keep MPS elevated, promoting muscle growth

• Animal proteins have better EAA composition and bioavailability than plant proteins

• If you’re consuming a plant based diet, aim for 1.3-1.5 grams of protein/lb BW each day to optimize muscle growth

• Rates of protein digestion and duration of MPS elevation depend on the quality, quantity, and other macronutrients consumed with the meal