How Much Protein Should You Eat Per Day?

Proteins are the only macronutrients that contain nitrogen, which makes them irreplaceable in the body. They are the raw material for every muscle tissue, every digestive enzyme, every peptide hormone (insulin, glucagon, IGF-1), and every antibody of the immune system. Hemoglobin, which carries oxygen in the blood, is itself a protein, globin. Without sufficient protein intake, the body cannot repair damaged tissues, synthesize its functional molecules, or maintain lean mass.

Two concepts that popular nutrition media frequently conflate must be distinguished: minimal intake and optimal intake. Minimal intake is the threshold below which deficiencies appear, muscle loss, immune suppression, impaired wound healing. Optimal intake, on the other hand, is the amount that supports muscle protein synthesis (MPS), post-exercise recovery, satiety, and favorable body composition. These two figures are very different, and the confusion between them is one of the most frequent errors in mainstream nutritional advice.

The protein debate is one of the most thoroughly documented areas of sports nutrition. Hundreds of randomized clinical trials, meta-analyses covering thousands of subjects, and the official positions of the ISSN (International Society of Sports Nutrition), the ACSM (American College of Sports Medicine), and the WHO now provide a solid evidence base for precise and reliable recommendations.

The WHO RDA (Recommended Dietary Allowance) is 0.8 g of protein per kilogram of body weight per day. This figure, often cited as the "sufficient dose," is in fact the minimum threshold calculated to prevent deficiencies in a healthy sedentary adult, it does not represent the optimal amount for health, performance, or body composition. For a 70 kg person, that equals 56 g of protein per day, roughly the amount in two medium chicken fillets.

The ISSN (International Society of Sports Nutrition, official 2017 position stand) sets the optimal range for physically active individuals at 1.6 to 2.2 g/kg/day. For a 70 kg person, this translates to 112 to 154 g of protein per day, two to three times the WHO recommendation. This range maximizes muscle protein synthesis, post-training recovery, and body composition in active adults.

Older adults represent a special case: anabolic resistance, the diminished muscular response to a given protein dose, develops progressively after age 60. The ESPEN (European Society for Clinical Nutrition and Metabolism) recommends 1.2 to 1.5 g/kg/day for this population, rising to up to 2 g/kg/day in cases of malnutrition or acute illness. For a 70 kg person over 65, that means 84 to 105 g/day, well above the WHO threshold, and frequently under-consumed in care facilities.

For muscle gain, the recommended range is 1.6 to 2.2 g/kg/day combined with a moderate caloric surplus. The meta-analysis by Morton et al. (2018, *British Journal of Sports Medicine*, n = 1,800 participants) is the benchmark in this field: it shows that lean mass gains are maximized around 1.62 g/kg/day, and that intake beyond 2.2 g/kg/day yields no additional measurable muscle benefit. Beyond that threshold, excess protein is simply oxidized as an energy source.

For weight loss, protein plays an even more strategic role. The recommended intake is 1.2 to 1.6 g/kg of lean body mass (not total weight, to avoid overestimating needs in cases of significant obesity). The satiating effect of protein is well documented: it reduces ghrelin levels (the hunger hormone) and stimulates the release of PYY and GLP-1 (satiety hormones), resulting in a spontaneous 10 to 15% reduction in total caloric intake among subjects who increased their protein consumption. Protein also preserves muscle mass during a caloric deficit, which is critical for maintaining basal metabolic rate during dieting.

For weight maintenance in an active adult without specific body recomposition goals, 1.2 to 1.4 g/kg/day is a reasonable target. Endurance athletes (long-distance running, cycling, swimming) need 1.2 to 1.6 g/kg/day, since branched-chain amino acids (BCAAs), particularly leucine and isoleucine, are partially oxidized as an energy substrate during prolonged effort. Pregnant and breastfeeding women should add approximately +25 g/day to their baseline intake, according to ANSES recommendations.

The concept of the leucine threshold is central to understanding how to optimize muscle protein synthesis (MPS). Leucine is the essential amino acid that activates the mTORC1 complex, the primary regulator of MPS. To trigger an optimal anabolic response, each meal must provide 2 to 3 g of leucine, which corresponds to approximately 20 to 40 g of protein depending on the food source. A 150 g steak (31 g of protein) provides about 2.4 g of leucine; 200 g of cottage cheese (22 g of protein) provides approximately 2.1 g. Below this threshold, MPS remains sub-optimal even if the total daily intake is met.

The ideal distribution supported by the literature is 4 protein meals per day of approximately 0.4 g/kg of body weight each. For a 70 kg person targeting 1.6 g/kg/day (112 g/day), that means 4 meals of 28 g of protein. This regular distribution maximizes the total duration over which MPS is activated across 24 hours, compared to an asymmetric distribution concentrating protein in one or two meals.

Regarding peri-workout timing, the "anabolic window", the idea that protein must be consumed within 30 minutes of training, is an oversimplification. The meta-analysis by Aragon & Schoenfeld (2013) shows this window is actually 3 to 5 hours, and that total daily intake remains the priority over precise 15-minute timing. However, slow-release protein (casein) before bed has documented benefits: the study by Res et al. (2012) showed a 22% increase in overnight MPS in subjects who consumed 40 g of casein before sleep, compared to the control group.

The DIAAS score (Digestible Indispensable Amino Acid Score), adopted by the FAO in 2013, is now the international standard for assessing the quality of a dietary protein. Unlike the older PDCAAS score, it accounts for actual digestibility measured in the small intestine. DIAAS scores of the best animal protein sources are: whole eggs (1.18), whole milk (1.14), whey protein (1.09), cooked chicken (1.08), salmon (0.96). A score above 1.0 indicates that the protein exceeds requirements for indispensable amino acids.

Plant proteins generally have lower DIAAS scores because they are deficient in one or more essential amino acids, lysine for cereals, methionine for legumes. The combination of rice + legumes (beans, lentils, chickpeas) creates a complete amino acid profile and forms the protein foundation of many traditional cuisines worldwide. Soy is the notable plant-based exception, with a DIAAS score of 0.91 and a near-complete amino acid profile.

In terms of protein content per 100 g of cooked or as-served product: cooked chicken 31 g, canned tuna 26 g, cooked ground beef 26 g, tempeh 19 g, cooked edamame 11 g, cooked lentils 9 g, firm tofu 8 g, skyr 10 g, 0% quark 8 g, whole egg 13 g, cooked quinoa 4.4 g. The bioavailability of plant proteins is 70 to 85% compared to 90 to 95% for animal proteins, vegans and strict vegetarians should increase their intake by 10 to 15% to compensate.

"Protein destroys the kidneys." This is only true in patients with pre-existing chronic kidney disease, for whom nephrologists do indeed recommend reducing protein intake. In healthy adults, the evidence is clear: the study by Antonio et al. (2016, *Journal of the International Society of Sports Nutrition*) followed athletes consuming 2.2 g/kg/day for 2 years without any adverse effects on kidney markers (creatinine, GFR, urinary albumin). Healthy kidneys adapt without difficulty to high protein intakes.

"You can't absorb more than 30 g of protein per meal." The body fully digests and absorbs quantities well above 30 g per meal, digestion simply takes longer. What is true, however, is that MPS (muscle protein synthesis) plateaus after 20 to 40 g of high-quality protein per meal. The excess isn't "wasted": it is oxidized as an energy source or converted to glucose (gluconeogenesis). For body recomposition goals, it is therefore better to distribute protein across several meals than to concentrate 100 g in a single sitting.

"You need a protein shake within 30 minutes of training." The anabolic window actually lasts 3 to 5 hours, not 30 minutes. If you ate a protein-rich meal 1 to 2 hours before your session, your body still has sufficient substrates for post-exercise protein synthesis. The absolute priority remains total daily protein intake, not timing to the nearest 15 minutes.

"Vegans can't get enough protein." False. The combination of legumes + grains + soy can meet 1.6 g/kg/day without supplementation. The practical rule is simple: include soy (tempeh, edamame, firm tofu) in at least two meals per day, combine legumes and whole grains at other meals, and increase quantities by 10 to 15% to account for lower plant protein bioavailability.

Can you eat too much protein? From a kidney health standpoint in healthy adults, the evidence shows no adverse effects below 3.5 g/kg/day. However, beyond 2.2 g/kg/day, excess intake no longer generates additional muscle benefit and is simply oxidized for energy. In practice, a very high-protein diet may reduce dietary diversity and limit intake of quality complex carbohydrates and fats, which can impair performance and long-term health.

How much protein for a vegan or vegetarian? An active vegan targeting 1.6 g/kg/day should consume approximately 1.75 to 1.85 g/kg/day of plant protein to account for lower digestibility. Strategic combination of plant sources matters: tempeh (19 g/100 g), edamame (11 g/100 g), cooked lentils (9 g/100 g), cooked chickpeas (9 g/100 g), firm tofu (8 g/100 g), seitan (25 g/100 g). Soy remains the only plant protein with a near-complete amino acid profile and should be the cornerstone of any athletic vegan diet.

Is whey protein necessary? No. Whey is a convenient supplement, fast-digesting (plasma amino acid peak in 60 to 90 minutes) with a high DIAAS score (1.09), but it is not essential if the regular diet already covers protein needs. For people struggling to meet their daily target through food alone, or after intense sessions requiring rapid recovery, it is an effective and cost-efficient complement per gram of protein.

Does protein make you gain weight? Not directly. Protein provides 4 kcal per gram, the same as carbohydrates. It does not cause fat gain on its own, but a very high-protein diet can produce an overall caloric surplus if other macronutrients are not adjusted accordingly. Protein also has the highest thermic effect of all macronutrients (25 to 30% of ingested calories are spent on digestion and assimilation, versus 6 to 8% for carbohydrates and 2 to 3% for fat), making it the macronutrient with the lowest net caloric density.

The information presented in this guide is provided for educational and informational purposes only. It does not constitute personalized medical advice and is not a substitute for consultation with a qualified healthcare professional.

Consult a physician or registered dietitian before significantly modifying your protein intake, particularly in cases of kidney disease (even mild), pregnancy, breastfeeding, strict vegan diets, or competitive sport. The figures presented are based on the following sources: ISSN Position Stand 2017 (Morton et al., *Journal of the International Society of Sports Nutrition*), Morton et al. meta-analysis 2018 (*British Journal of Sports Medicine*, n = 1,800), FAO DIAAS 2013, WHO RDA, ESPEN Guidelines 2018, Harvard T.H. Chan School of Public Health. Values are population averages and may vary by individual, food preparation method, and measurement technique.