Lots and lots of studies have shown that consuming higher intakes of protein, especially when performing weight training, is associated with having more muscle. Muscle is important for a healthy functioning body, and not to be overlooked just because you’re not a bodybuilder.
Protein is used for a wide variety of functions, including but not limited to cell signaling, transport, storage, immune system regulation, DNA replication, enzymatic activities, and proteins are structural components of cells like muscle cells.
Proteins are made up amino acids, which are commonly referred to as the “building blocks” of protein. When we eat protein, our bodies break it down in to amino acids. Our bodies in turn take these amino acids and create other proteins that our body needs in order to function. If you don’t eat enough protein, your body will need to get amino acids by breaking down cells, tissue, and muscle in order to continue functioning, which hinders muscle growth. When you eat enough protein, the body has enough amino acids to continue to function without breaking down tissue, and thus will give your body a chance to build new muscle.
So, the question becomes, how much protein do you need in order to maximize muscle growth? Although there are always different and unique variables to consider between each person, there is definitely some hard evidence surrounding this topic, and some fairly easy and attainable goals to meet in regards to protein intake. In this article, I’m mostly focusing on the minimum amount of protein to maximize muscle growth, while also avoiding eating excess protein.
- 20-25 g of protein per meal will maximally stimulate muscle protein synthesis in most people
- Consume 20-25 g protein at each meal throughout the day, immediately following resistance training, and right before bed for maximum muscle protein synthesis
- If you consume only plant-based protein, you’ll need to up your protein intakes to 25-30 g each meal, post-exercise, and before bed
Muscle Protein Synthesis
A lot of this article is going to refer to something known as muscle protein synthesis, so it’s a good idea to get an understanding of what it is. Muscle protein synthesis is the main component to muscle building. In order for muscle building to occur, we need to stimulate muscle protein synthesis, and muscle protein synthesis needs to be greater than muscle protein breakdown. Most of the studies looking at muscle building use muscle protein synthesis as a measurement tool to see how good the chances are of building muscle. Two things that stimulate muscle protein synthesis are weight training and consuming certain amounts of protein.
Hypertrophy, the word used to define enlarging cells and muscle gains, is enhanced by nutrition, particularly protein. The amount of dietary protein intake can influence the amount of muscle a person has. (1)
In order to build muscle, we need to be in a positive net protein balance. Net protein balance = Muscle protein synthesis – muscle protein breakdown. If you are breaking down protein more than you are synthesizing, you will be in a negative net protein balance, which means it’s physically impossible for you to build muscle. Basically, what you need to do is increase muscle protein synthesis. The two best ways are to perform resistance exercises, and to consume adequate amounts of protein, carbohydrate, and fat. In this article, I’m going to focus on what protein amount is ideal in order maximize muscle growth, assuming that all other nutrients and calories are being meet. (2)
Current Recommended Dietary Allowance (RDA)
The current Recommended Dietary Allowance (RDA) for protein is set at 0.8 g/kg of body weight, which is the equivalent of 0.36 g/lb of body weight. For a 175 lb person, this means that a daily dietary intake of 63 g of protein should be sufficient to maintain muscle and healthy function. The studies that support the idea that high a dietary protein intake increases muscle protein synthesis and mass include protein intakes well above the RDA of 0.8 g/kg. One reason for this is that the RDA of 0.8g/kg/day is set for sedentary, healthy, adult Americans, and is the amount that replaces protein losses and prevents protein deficiencies. People who partake in some sort of exercise and training, particularly hard resistance training need significantly more protein, likely twice as much or more. If you are a beginner bodybuilder or starting some form of training you’ll actually need more protein than people who are well conditioned, probably because the well trained individuals are able to utilize protein more efficiently. (3)
Although the amount of protein you need to consume to maximize muscle growth can depend on your age, gender, and activity level, a good rule of thumb is to consume 20-25 grams of protein at each meal. It has been shown that consuming 20 g of protein in one meal reaches the upper limit of muscle protein synthesis in young men. This means that consuming more than 20 g of protein will not further stimulate muscle protein synthesis significantly. (4)
It has also been demonstrate that consuming 30 g of protein in one meal is as effective at stimulating muscle protein synthesis as a meal containing a whopping 90 g of protein. One possible explanation for this is the muscles become saturated with amino acids, and more amino acids will not do any good. Once this occurs, excess amino acids will be diverted and oxidized for other metabolic processes beyond muscle protein synthesis. (4)
So, it’s safe to say that for most people, maximal muscle protein synthesis can be reached at 20-30g of protein consumption per meal. (5) If you are consuming plant-based protein sources, you’ll need to consume more at each meal. Aim for 25-30 g of plant-based protein, because plant proteins are less digestible and harder to absorb. (6)
Weightlifters who want to maximize muscle hypertrophy need to consume 1.2-2.0 g protein/kg body weight (this equates to 0.55 – 0.9 g protein/lb body weight). The higher end of this range is close to the rule of thumb of 1 g of protein per 1 lb of body weight for bodybuilding. (7)
There are definitely some mixed results when it comes to protein timing. However, a lot of studies have shown that protein timing is indeed an important factor to consider when trying to build muscle. Therefore, I’m going to focus on the studies that show protein timing to be beneficial.
One study determined that within 3 hours and 45 minutes following the consumption of a high protein meal (0.5 g/kg protein), 20 g of protein will be sufficient to stimulate maximum muscle protein synthesis again. (4)
We already know that 20 g of protein will likely saturate the muscles with amino acids and maximize muscle protein synthesis. This study tells us that we can do it all over again within less than 4 hours of our last meal, and likely sooner.
It’s important to spread protein consumption throughout the day, because it does increase your ability to build muscle. One study found that consuming 3 meals containing 30 g of protein at each meal stimulated muscle protein synthesis better than eating 1 meal containing 10 g, 1 meal containing 16 g, and then eating 1 large meal in the evening containing 63 g. This is because 30 g of protein is maximizing muscle protein synthesis, and 10-16 g of protein isn’t quite enough to maximize muscle protein synthesis.
Although the evidence is a bit mixed on whether there is a window of opportunity to consuming protein immediately following exercise, I think it would still be a good idea to try to do this. The reason being is that it doesn’t hurt to consume protein within an hour of working out, and some studies have shown it to have a favorable effect on muscle protein synthesis. (8)
One review found that consuming protein either immediately before or after resistance training increases muscle building more than not consuming anything during that time. (2) If it doesn’t seem to help you, then I wouldn’t put the effort in, but it potentially could help. The window of anabolic opportunity after exercising has been shown to be much greater than 1 hour, and so it’s not critical to immediately drink a protein shake or consuming large meal immediately after resistance training. (6) However, we are trying to maximize muscle building, so have 20 g or so of protein after resistance training.
Eating some protein before sleeping at night is also recommended. Consuming a slow releasing protein (like casein) before going to bed stimulates muscle protein synthesis better than not consuming anything before bed. (6) It makes sense. One study found that consuming 27.5 g protein and 15 g carbohydrate before sleep in conjunction with resistance training increases muscle protein synthesis overnight compared to placebo, resulting in an increase in muscle mass. However, the group that was consuming the protein supplement was technically consuming more calories, 746 calories more actually. If the protein supplement is excluded from the total calories, then the two groups were consuming the same amounts. So, we can’t really say 100% that an increase in muscle mass is due to the protein, when it’s more likely due to the overall increase in both protein and carbohydrate calories. (5)
What Type of Protein
Not all types of protein are created equal. Animal sources of protein offer all of the essential amino acids and are more digestible than plant sources of protein. That being said, it’s perfectly fine to consume only plant sources of protein, and you can definitely build muscle doing so. I recommend consuming both animal and plant sources of protein.
Although some studies show one type of protein is better than another, I think it’s more important to not complicate things, and instead first focus on the quantity, and then consider whether the protein you’re consuming is from plant-sources and/or animal sources. If it’s from plant sources, you need an extra 5-10 g of protein per meal in order to maximize muscle protein synthesis.
Get Enough Calories, Too
Calories are an important part of muscle building. If you’re not eating enough calories, you’re not going to put on muscle, no matter how much protein you’re consuming. For instance, one study found that men who run 5 to 10 miles a day and are in a caloric deficit, but consuming 2 g/kg of protein (that’s a lot), were still in a significant negative nitrogen balance. This means that they were not able to build muscle, and instead were breaking down their own tissues to meet their bodies’ protein and caloric needs. If we don’t eat enough calories, then we’ll end up breaking down our bodies instead of building them up. (9)
Elderly and Illnesses
The loss of muscle can greatly affect how well we function in day to day tasks. This is more apparent and easy to see in elderly. Once muscle is lost, it’s pretty hard to get it back, especially if you’re unhealthy and have a difficult time exercising. Typically, when muscle is lost, fat is gained back. This is why it’s important to try to maintain as much healthy lean body mass as you can. Having adequate muscle and strength isn’t only healthy, it also allows us to be independent and live an active lifestyle. (10)
The loss of muscle is an important topic for elderly. Age-related muscle loss, known as sarcopenia, greatly affects elderly and their ability to complete day to day tasks and remain independent. Elderly need to consume higher amounts of protein. Resistance training and adequate intakes of protein does help age-associated loss of muscle.
Although the loss of muscle mass can be caused by many factors, inadequate protein intake is a major contributing factor. Intakes of 1.2 g/kg and 1.5 g/kg of protein has been shown to prevent the loss of muscle-mass. (1)
Those who have inflammatory conditions associated with illnesses also need to consume more protein, because protein is broken down and for both inflammatory and catabolic responses. (11)