Protein plays countless vital roles in maintaining overall health and well-being. But ensuring adequate intake is particularly important for anyone exercising regularly and with goals to optimize the repair, growth, and adaptation of muscle to improve strength and fitness.
Proteins are made up of amino acids, which act as the building blocks needed to form the structural basis of most of the body’s tissues — including skeletal muscle. Resistance training — and, as described below, endurance training — puts stress on the muscles by causing microscopic damage, leading to the breakdown of muscle protein.
It’s this muscle damage that stimulates the body to not only repair itself, but also to adapt and grow so that it can better cope with repeated future bouts of exercise. Over time, with consistent training, proper nutrition, and sufficient rest, the muscle fibers repair and modify, leading to increases in muscle size, strength, and/or efficiency.
So how much protein is needed to maintain body tissues and support muscular adaptations? The answer depends on numerous factors, including individual goals, body weight, training intensity, and overall diet. Here, we’ll break down the science behind optimal protein intakes based on some of the most common health and fitness goals.
How Much Protein Do You Actually Need?
For General Health
In the US, the recommended dietary allowance (RDA) for protein in healthy adults is a modest 0.8 grams of protein per kilogram of body weight. For a healthy adult weighing 180 pounds (about 82 kilograms), this equates to 66 grams of protein per day.
It’s important to note that the RDA is the amount of a nutrient calculated to meet basic nutritional requirements for nearly all (97.5%) of adults. For most sedentary to moderately active adults, this should be enough to support overall health and ensure the important functions work properly, including the maintenance of tissues, functioning of the immune system, and formation of hormones and enzymes. But for anyone who exercises regularly and has goals of building muscle, improving endurance, or losing weight, it can be helpful to increase protein intake beyond the RDA.
For Building Muscle
For decades, many gym goers bought into the traditional belief that aiming for one gram of protein per pound of body weight was required to build muscle. That means that a 180-pound (~82-kilogram) adult would need to consume 180 grams of protein every single day (around 2.2 grams of protein per kilogram of body weight). Putting such an emphasis on protein can be difficult to sustain, and often results in reducing intake of other healthful food groups like whole grains and starchy vegetables in order to maintain energy balance, which can result in lower overall dietary quality.
The latest, most comprehensive research shows that the optimal protein requirements for building muscle are in fact lower than those previous estimations. In 2018, an analysis of 49 controlled trials found that, when combined with regular resistance training, increasing protein intake only led to greater improvements in muscle growth up to an average of 1.6 grams of protein per kilogram of body weight per day1.
These findings were supported by another 2022 assessment of 82 controlled trials, which found that, alongside strength training programs, increases in muscle strength plateaued at an average of 1.5 grams of protein per kilogram of body weight per day2. This equates to around 123 grams of protein for the 180-pound strength-training athlete, or at least 30 grams of protein across four meals (this is why FYTA Elite Plant Protein was formulated to contain significantly more protein per serving than most other brands). As discussed at the end of this article, there may be some individual variation in optimal protein intake, but for most athletes looking to build muscle, these levels should provide all the protein they need.
For Endurance-Based Exercise
Although endurance athletes aren’t necessarily trying to put on muscle, they usually have increased protein requirements due to several factors associated with their training and performance demands. Endurance training still places significant stress on the muscles, leading to muscle damage and breakdown, so protein is crucial for repairing and rebuilding the damaged muscle tissue. The adaptations to endurance training include increased mitochondrial density, improved oxygen utilization, and enhanced energy production pathways. Dietary protein is involved in all of these adaptations, as it provides the building blocks for new proteins involved in these processes.
Prolonged endurance exercise can also increase the oxidation (breakdown) of amino acids for energy. This occurs as the body depletes glycogen stores and shifts to using alternative fuel sources, including amino acids, through a process known as gluconeogenesis. To compensate for this increased protein breakdown, endurance athletes also need higher protein intakes than the RDA to support muscle maintenance.
To account for these processes, general recommendations for endurance athletes looking to support their performance, recovery, and general health sit at around 1.2–1.4 grams of protein per kilogram of body weight, but can be even higher following more intense or prolonged endurance exercise3,4. This would equate to around 98-115 grams of protein or more per day for the 180-pound athlete.
For Body Fat Reduction
For most people, losing unwanted body fat is as straightforward as consuming fewer calories than they burn. While exercising more often can be useful in achieving this goal, research has shown that food is the most important factor, and that eating a more plant-forward diet is the healthiest and often the most effective approach, both for the short and long-term5,6.
Many people who want to shed body fat aren’t concerned that in doing so, they may lose some muscle mass in the process. This is especially true if they try to lose weight rapidly and/or don’t consume enough protein.
However, for those who want to preserve (or even gain) muscle mass while reducing body fat, eating more protein than the recommended dietary allowance can be a useful strategy, especially when combined with resistance training. This is because consuming extra protein during a caloric deficit can help offset muscle protein breakdown7.
Even if preserving or building muscle isn’t a priority, doing so when seeking to reduce body fat can be advantageous because muscle tissue is highly metabolic, helping you burn more calories, even at rest. Additionally, higher protein meals can help us feel fuller for longer, curbing cravings and reducing overall energy intake8.
General recommendations for those wishing to prevent muscle breakdown during body fat loss vary depending on individual factors such as age, sex, weight, activity level, and specific goals, but tend to fall in the range of 1.6 to 2.2 grams of protein per kilogram of body weight7 (or between around 131-180 grams for a 180-pound adult).
Other factors that influence protein requirements:
On top of the type of training and physical goals, there are a number of other factors that will influence what the optimal protein intake is for each individual. For instance:
- Body fat percentage: most of the ranges given above have been calculated for individuals with a healthy body mass index (BMI), so requirements are likely to be lower for people with a higher body fat percentage, or a little higher for anyone who is underweight
- Exercise intensity: athletes aiming to build muscle rapidly through more extreme exercise regimens, such as bodybuilders and powerlifters, may benefit from increasing protein intake beyond the established intakes described above for building muscle
- Training experience: there is evidence that well-trained, experienced athletes require less protein than people first initiating an exercise programme9
- Age: studies show that for older adults, protein intakes higher than the RDA can lead to greater muscle strength and lean body mass when combined with resistance exercise10,11
- Overall diet: the context of the diet as a whole is important to consider, since the consumption of adequate energy — particularly from carbohydrates — is important to help limit the amount of amino acids being oxidized (burned) as an alternative energy source, rather than being used for protein synthesis
Other factors including genetics and specific health conditions can affect recommended protein intakes. Consulting with a healthcare professional or registered dietitian can help you determine your specific protein needs.
The Take Home Message
For anyone with goals of increasing strength, improving endurance or losing weight, increasing protein intake above the recommended dietary allowance can be useful. At the same time, it’s important not to overemphasize protein, which can displace other important food groups like wholegrains and starchy fruit and vegetables and often results in reduced overall dietary quality. Aiming for the majority of protein to come from a balance of whole plant foods helps to ensure the widest range of important vitamins, minerals and other healthy plant compounds are taken in. Additionally, high quality protein supplements like FȲTA Elite Plant Protein can be a quick, convenient, and cost-effective way to boost intake to meet the optimal protein levels required to reach a range of health and fitness goals.
Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., Aragon, A. A., Devries, M. C., Banfield, L., Krieger, J. W., & Phillips, S. M. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British journal of sports medicine, 52(6), 376–384. https://doi.org/10.1136/bjsports-2017-097608
Tagawa, R., Watanabe, D., Ito, K., Otsuyama, T., Nakayama, K., Sanbongi, C., & Miyachi, M. (2022). Synergistic Effect of Increased Total Protein Intake and Strength Training on Muscle Strength: A Dose-Response Meta-analysis of Randomized Controlled Trials. Sports medicine - open, 8(1), 110. https://doi.org/10.1186/s40798-022-00508-w
Jäger, R. et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14, 20. https://doi.org/10.1186/s12970-017-0177-8
Kato, H., Suzuki, K., Bannai, M., & Moore, D. R. (2016). Protein Requirements Are Elevated in Endurance Athletes after Exercise as Determined by the Indicator Amino Acid Oxidation Method. PloS one, 11(6), e0157406. https://doi.org/10.1371/journal.pone.0157406
Dinu, Monica, Abbate, Rosanna, Gensini, Gian Franco, Casini, Alessandro, & Sofi, Francesco. (2016). Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Critical Reviews in Food Science and Nutrition, 57(17), 3640-3649. https://doi.org/10.1080/10408398.2016.1138447
Huang, Ru-Yi, Huang, Chuan-Chin, Hu, Frank, & Chavarro, Jorge. (2016). Vegetarian Diets and Weight Reduction: A Meta-Analysis of Randomized Controlled Trials. Journal of General Internal Medicine, 31(1), 109-116. https://doi.org/10.1007/s11606-015-3390-7
Moon, J., & Koh, G. (2020). Clinical Evidence and Mechanisms of High-Protein Diet-Induced Weight Loss. Journal of obesity & metabolic syndrome, 29(3), 166–173. https://doi.org/10.7570/jomes20028
Belza, A., Ritz, C., Sørensen, M. Q., Holst, J. J., Rehfeld, J. F., & Astrup, A. (2013). Contribution of gastroenteropancreatic appetite hormones to protein-induced satiety. The American journal of clinical nutrition, 97(5), 980–989. https://doi.org/10.3945/ajcn.112.047563
Moore, D. R., Del Bel, N. C., Nizi, K. I., Hartman, J. W., Tang, J. E., Armstrong, D., & Phillips, S. M. (2007). Resistance training reduces fasted- and fed-state leucine turnover and increases dietary nitrogen retention in previously untrained young men. The Journal of nutrition, 137(4), 985–991. https://doi.org/10.1093/jn/137.4.985
Coelho-Júnior, H. J., Calvani, R., Tosato, M., Landi, F., Picca, A., & Marzetti, E. (2022). Protein intake and physical function in older adults: A systematic review and meta-analysis. Ageing research reviews, 81, 101731. https://doi.org/10.1016/j.arr.2022.101731
Nunes, E. A., Colenso-Semple, L., McKellar, S. R., Yau, T., Ali, M. U., Fitzpatrick-Lewis, D., Sherifali, D., Gaudichon, C., Tomé, D., Atherton, P. J., Robles, M. C., Naranjo-Modad, S., Braun, M., Landi, F., & Phillips, S. M. (2022). Systematic review and meta-analysis of protein intake to support muscle mass and function in healthy adults. Journal of cachexia, sarcopenia and muscle, 13(2), 795–810. https://doi.org/10.1002/jcsm.12922