Let’s Talk Protein
What is protein?
Protein is a macronutrient required for almost all processes and functions in our bodies. It builds and repairs bodily tissues, forms enzymes for chemical reactions and hormones for chemical messages, aids in fluid and pH balance, helps with nutrient transport, fights infection, promotes wound healing, and can be used as an energy source when carb and fat intake is insufficient (Diker, 2023). In the fitness and nutrition industry, protein is often discussed with regard to its role in exercise recovery and muscle protein synthesis (MPS), or the body’s adaptive response to exercise that contributes to muscle growth.
Amino acids
Protein is made up of compounds called amino acids, of which there are twenty different types. Amino acids are often referred to as the “building blocks of protein” because they combine to form the proteins responsible for various bodily functions. To keep this succinct, I won’t list out all twenty and their unique functions, but it’s important to understand the two categories of amino acids: essential and nonessential.
Eleven of the amino acids are considered “nonessential” because our bodies can produce them—we don’t need to get them from external sources. The remaining nine are “essential”—our bodies can’t produce them, so they must be consumed via food or supplements. A healthy, balanced diet that includes a variety of protein sources will likely provide you with an adequate amount of essential amino acids (EAAs) to support protein synthesis and function, but more on that later.
Dietary Reference Intakes
Many different guidelines exist pertaining to daily protein needs. These guidelines are referred to as Dietary Reference Intakes (DRIs), and some DRIs are thought to provide better recommendations than others. Let’s talk about two DRIs in particular: Recommended Dietary Allowance and Acceptable Macronutrient Distribution Range.
Recommended Dietary Allowance
One guideline is the Recommended Dietary Allowance (RDA), which suggests we consume 0.8 grams of protein per kilogram of bodyweight per day. For example, if you weigh 60 kg, you would need 48 grams of protein per day. The problem with this recommendation is that it was originally based on the amount of protein required to avoid nitrogen loss in the body, not to promote optimal health or aid in exercise recovery (Wolfe et al., 2017). Studies have shown significant benefits to consuming more protein than the RDA, so it’s criticized for underestimating our protein needs. It might therefore be more appropriately thought of as the minimum intake guideline rather than the recommended intake.
Acceptable Macronutrient Distribution Range
Although the RDA is most commonly recognized as the recommendation for protein, the Acceptable Macronutrient Distribution Range (AMDR) may actually be a better guideline because it allows for individual variation in protein needs. The AMDR suggests that protein should comprise 10-35% of total daily calories. Based on a 2000-calorie diet, the AMDR would suggest that 200-700 of those calories come from protein. Protein contains four calories per gram, so this equates to 50-175 grams of protein per day, but would differ based on your unique caloric needs. The lower limit of this range, 10%, takes into account the minimum amount of protein required to avoid protein deficiencies, whereas the upper limit, 35%, accounts for extremely high-protein diets, often exceeding the needs of the average person. This begs the question: how much protein within the 10-35% range do you actually need? Well, it depends on your goals.
How much protein do I need?
Unless you have pre-existing kidney issues, there’s really no such thing as too much protein—although there is a point where your ROI flattens. There definitely is, however, such a thing as too little. The right amount of protein for you depends on your goals—whether you want to support optimal health, lose weight, build muscle, or improve endurance performance.
Protein for optimal health
Studies have shown that a daily protein intake of 1.2 grams per kilogram of bodyweight, which equates to about 15% of your total daily calories, is sufficient to promote optimal health (Phillips et al., 2016). A bodyweight of 60 kg would correspond to 72 grams of protein per day, according to this recommendation. This intake level mitigates sarcopenia, or declining muscle mass as we age, and provides sufficient protein for all vital bodily functions. It won’t necessarily optimize hypertrophy (muscle growth), weight loss, or endurance performance, but it’s adequate to support a healthy lifestyle.
Protein for weight loss
Before we talk about how much protein is optimal for weight loss, let’s first start with why protein is important for weight loss. Of the three macronutrients—protein, carbs, and fat—protein is the only one that has an effect on weight loss, and there are a few reasons for that. Firstly, protein is the most satiating of the three macros—it fills you up and keeps you full for longer, so you may consume fewer calories throughout the day when prioritizing protein because you’re more satiated (Carreiro et al., 2016). Secondly, metabolizing food requires energy, or calories, which is known as the thermic effect of food. Protein has the highest thermic effect of the three macros, meaning it burns the most calories during this process and may marginally support your calorie deficit as a result. Finally, a higher protein intake helps with muscle preservation during periods of caloric restriction (Hudson et al., 2020). Lean muscle mass contributes to a higher metabolic rate, which means the more muscle you have, the more calories you burn at rest—a helpful contribution in the pursuit of weight loss. However, when you’re in a calorie deficit, your body might break down muscle tissue in addition to fat to supplement the missing fuel, but this effect can be mitigated with an elevated protein intake. Specifically, a protein intake of 18-25% of total calories has been shown to be more effective in maintaining lean body mass compared to a protein intake of 10-12% (Wolfe et al., 2017).
With all that in mind, 1.6-2.2 grams of protein per kilogram of bodyweight per day is ideal for weight loss, and the bigger the calorie deficit, the more protein is required to offset lean body mass losses (Dieter, 2022; Hector & Phillips, 2018). If you weigh 60 kg, you would need 96-132 grams of protein per day if your goal is weight loss, depending on the magnitude of your calorie deficit.
Protein for muscle growth
Evidence shows that eating higher amounts of protein supports hypertrophy when combined with resistance training. While you can preserve muscle with adequate protein, resistance training must be incorporated alongside adequate protein if you’re looking to build muscle. Resistance training combined with protein consumption in excess of the RDA of 0.8 g/kg has demonstrated increased muscle mass compared to resistance training alongside the RDA (Hudson et al., 2020). This is because muscle protein synthesis, which is ultimately responsible for muscle growth, increases with higher protein intakes, so your body can more effectively build muscle.
The optimal range of protein for hypertrophy is the same as for weight loss—1.6-2.2 grams per kilogram of bodyweight per day (Schoenfeld & Aragon, 2018). However, the body can only utilize a certain amount of protein in one sitting for muscle protein synthesis, and since muscle growth is the goal, optimizing MPS is key. It’s therefore beneficial to spread your 1.6-2.2 g/kg out across four or more meals or snacks throughout the day, aiming for a minimum of 0.4 g/kg per meal to meet the lower end of the intake threshold or 0.55 g/kg to reach the upper end (Schoenfeld & Aragon, 2018). To use the same 60 kg example, this could look like a total daily protein intake of 96-132 grams, broken up into four meals and snacks of 24-33 grams of protein each.
You may be eating in a calorie surplus if your goal is hypertrophy, as building muscle requires additional energy. As a result, your protein intake as a proportion of the AMDR may seem smaller if you’re consuming more calories overall. If your maintenance calories are 1800 and you’re eating 100 grams of protein per day, this represents about 22% of your total daily calories. But if you’re in a calorie surplus, consuming 2100 calories per day, this same amount of protein would represent about 19% of your total daily calories. All that to say, it’s okay if your protein intake as a proportion of total calories decreases during a hypertrophic phase, as long as you’re still within that 1.6-2.2 grams per kilogram range.
Protein for endurance
Let’s talk about protein for endurance or cardio-related goals—things like running, swimming, and cycling, for example. Carbohydrates will likely have the strongest effect on performance for endurance exercise, but adequate protein is, of course, still crucial. The intensity of your training plays a big role in recommended protein intake, and the higher the intensity and/or longer the length of your training sessions, the more protein you’ll need. Generally speaking, a daily protein intake of 1.2-2.0 grams per kilogram of bodyweight is sufficient (Kato et al., 2016). For a bodyweight of 60 kg, the recommended protein intake would be 72-120 grams, or 14-24% of total daily calories, based on a 2000-calorie diet.
If your cardio sessions are of at least moderate intensity and lasting for over an hour, your protein intake should be within the upper limit of this range at a minimum of 1.8 g/kg, or 15% of total daily calories—whichever is the greater amount (Williamson et al., 2023). Protein may be used as fuel in prolonged endurance sessions, and it’s therefore crucial to replenish any protein that was lost while training (Kato et al., 2016).
Complete vs. incomplete proteins
Not all proteins are built the same, but I don’t think the average person needs to be overly concerned with the complexities of protein quality—that is, unless absolute maximization of protein is critical to your health and fitness goals. There is, however, one element of protein quality I do consider in my day-to-day nutrition: complete versus incomplete proteins.
A protein source is considered either complete or incomplete based on its essential amino acid profile. Complete proteins contain all nine EAAs, whereas incomplete proteins are missing at least one. Ensuring all nine essential amino acids are represented in your diet is critical to supporting vital bodily functions and will help to support your health and fitness goals as well.
Complete proteins
Animal proteins are considered complete proteins—things like chicken, beef, eggs, fish, and dairy—because they contain all nine essential amino acids. Soy is one of the few plant-based foods that also falls into this complete protein category, including soy milk, tofu, tempeh, edamame, etc. If you’re eating an adequate amount of protein from complete sources, then it’s likely your EAA intake will also be sufficient. With that being said, you don’t need to exclusively consume complete proteins in order to obtain all the essential amino acids—a diverse diet is the best diet. There’s a variety of other protein sources that aren’t considered complete but can still effectively contribute to your total daily protein and EAA intake.
Incomplete proteins
“Incomplete” doesn’t mean “bad,” as the name might suggest—incomplete protein sources are often highly nutritious and complementary to a healthy, balanced diet. Most plant-based protein sources, besides soy, are incomplete, including nuts, seeds, whole grains, legumes, etc. This means they’re lacking one or more essential amino acids, but you can still obtain all nine EAAs simply by combining incomplete protein sources to balance out amino acid gaps and supplement a complete protein. For example, beans lack the amino acid methionine, but brown rice is high in methionine; conversely, beans are high in the amino acid lysine, whereas brown rice is low in lysine. The beans provide the EAAs missing from the brown rice, and vice versa. A similar relationship is seen by combining peanut butter with whole grain toast, pita with hummus, lentils with rice—the world is your (plant-based) oyster.
You can also spread out your incomplete proteins throughout the day, and you don’t necessarily need to eat them at the same time (Dimina et al., 2021). You can eat your beans and rice together, or you can have beans with lunch and rice with dinner—either way, you’ll still reap the rewards of the incomplete protein combination.
The best way to ensure you’re meeting your protein and essential amino acid needs is to incorporate diverse sources of both complete and incomplete proteins into your diet. Such diversity will also help you meet other macro- and micronutrient needs alongside protein, because although our focus here is protein, we still need to consider how it fits within the broader context of our nutrition.
To weigh or not to weigh?
You can get super specific and weigh your food or use an app to track your exact protein intake, and if you enjoy getting that deep into the particulars, go right ahead! But, just as I don’t track my calories, I also don’t meticulously track my protein. If that approach isn’t for you either, rest assured you don’t need to get that granular to still reach your protein goals.
I typically aim for around 80-100 grams of protein per day to support my current goal of hypertrophy, but I never know exactly how much protein within that range I’m actually eating. Instead, I’ve familiarized myself with the approximate protein content of different foods so I can estimate my daily protein intake, but I don’t stress too much about it being precise. Most days, this puts me within my 80-100 gram range, but some days it doesn’t. I’m okay with sacrificing precision in the interest of my sanity, so I just try to incorporate at least one source of protein into every meal and snack, or at least most, and I’ll throw in a protein shake when I feel like I’m lacking.
There’s no right or wrong way to monitor your protein intake, whether you meticulously calculate it or take a more laid-back approach and estimate it. Do what works for you, but either way, it’s a good idea to familiarize yourself with the approximate amount of protein in various foods to make educated decisions about your nutrition.
Key takeaways
Protein is a complex topic, but having a general understanding of what protein is, how much you need, and where to get it from is a great foundation for being able to prioritize protein in a way that supports your body and your goals. You can choose to eat more protein than what’s recommended, since additional protein is rarely a bad thing, but avoid eating less than the recommendations to ensure you’re giving your body what it needs.
The good news is that most people are already consuming an adequate amount of protein, with daily protein intake averaging around 79.47 grams per day, or about 16% of total calories based on a 2000-calorie diet (Auclair & Burgos, 2020). This means that your protein intake might already be sufficient, but if it’s not, it’s likely that you’ll only need to make minor changes to accommodate that additional protein. Strive to incorporate at least one substantial source of protein into each meal, and it’s even better if you can do the same with snacks. Remember that variety is the spice of life, and your protein sources should have variation, too. Also, contrary to what gym bros might suggest, protein isn’t everything—pay attention to other macro- and micronutrients to promote optimal nutrition overall, not just optimal intake of one component.
Below is an overview of the recommended daily protein intakes we discussed, so go grab a protein shake and start crushing your goals.
OPTIMAL HEALTH:
1.2 g/kg/day
WEIGHT LOSS:
1.6-2.2 g/kg/day
MUSCLE GROWTH (HYPERTROPHY):
1.6-2.2 g/kg/day
ENDURANCE:
1.2-2.0 g/kg/day
References
Auclair, O. & Burgos, S. A. (2020). Protein consumption in Canadian habitual diets: usual intake, inadequacy, and the contribution of animal- and plant-based foods to nutrient intakes. Applied Physiology, Nutrition, and Metabolism, 46(5), 501-510. https://doi.org/10.1139/apnm-2020-0760
Carreiro, A. L., Dhillon, J., Gordon, S., Jacobs, A. G., Higgins, K. A., McArthur, B. M., Redan, B. W., Rivera, R. L., Schmidt, L. R., & Mattes, R. D. (2016). The macronutrients, appetite and energy intake. Annual Review of Nutrition, 36, 73-103. https://doi.org/10.1146/annurev-nutr-121415-112624
Dieter, B. (2022). Protein and weight loss: How much protein do you need to eat per day? NASM. https://blog.nasm.org/nutrition/how-much-protein-should-you-eat-per-day-for-weight-loss?utm_source=blog&utm_medium=referral&utm_campaign=organic&utm_content=safeandhealthyweightloss
Diker, A. (2023). Introduction to Nutrition. LibreTexts.
Dimina, L., Rémond, D., Huneau, J.-F., & Mariotti, F. (2021). Combining Plant Proteins to Achieve Amino Acid Profiles Adapted to Various Nutritional Objectives—An Exploratory Analysis Using Linear Programming. Frontiers in Nutrition, 8. https://doi.org/10.3389/fnut.2021.809685
Hector, A. J. & Phillips, S. M. (2018). Protein Recommendations for Weight Loss in Elite Athletes: A Focus on Body Composition and Performance. International Journal of Sport Nutrition and Exercise Metabolism, 28(2), 170-177. https://doi.org/10.1123/ijsnem.2017-0273
Hudson, J. L., Wang, Y., Bergia, R. E., III., & Campbell, W. W. (2020). Protein Intake Greater than the RDA Differentially Influences Whole-Body Lean Mass Responses to Purposeful Catabolic and Anabolic Stressors: A Systematic Review and Meta-analysis. Advances in Nutrition, 11(3), 548-558. https://doi.org/10.1093/advances/nmz106
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). https://doi.org/10.1371/journal.pone.0157406
Phillips, S. M., Chevalier, S., & Leidy, H. J. (2016). Protein "requirements" beyond the RDA: implications for optimizing health. Applied Physiology, Nutrition, and Metabolism, 41(5), 565-572. https://doi.org/10.1139/apnm-2015-0550
Schoenfeld, B. J. & Aragon, A. A. (2018). How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. Journal of the International Society of Sports Nutrition, 15(10). https://doi.org/10.1186/s12970-018-0215-1
Williamson, E., Fung, H. J. W., Adams, C., West, D. W. D., & Moore, D. R. (2023). Protein Requirements Are Increased in Endurance-Trained Athletes but Similar between Females and Males during Postexercise Recovery. Medicine & Science in Sports & Exercise, 55(10), 1866-1875. doi: 10.1249/MSS.0000000000003219
Wolfe, R. R., Cifelli, A. M., Kostas, G., & Kim, I.-Y. (2017). Optimizing Protein Intake in Adults: Interpretation and Application of the Recommended Dietary Allowance Compared with the Acceptable Macronutrient Distribution Range. Advances in Nutrition, 8(2), 266-275. https://doi.org/10.3945/an.116.013821