How much protein do you need?

The RDA for adults is 0.8 grams of protein per kilogram of body weight a day, about 0.36 grams per pound.^[1] It is set to prevent deficiency in nearly all healthy adults.^[2] The 2025–2030 Dietary Guidelines for Americans set a higher goal of 1.2 to 1.6 g/kg a day, adjusted to your calorie needs.^[3]

The official number: the RDA

Recommended Dietary Allowance (RDA)

The daily intake that meets the needs of nearly all (97–98%) healthy people.^[2] For protein, it was set as the least you need to eat to avoid losing body nitrogen.^[2]

The National Academies reaffirmed 0.8 g/kg a day as the protein RDA for adults in 2002.^[1] The average requirement it is built on is 0.66 g/kg a day.^[2]

Pregnancy raises the RDA to 1.1 g/kg a day.^[4]

There is also a range for protein as a share of calories: 10% to 35% for adults.^[1] Most Americans already eat more than the minimum.^[5] In US survey data from 2001 to 2014, protein made up 14% to 16% of total calories.^[5]

Is the RDA too low?

This is where researchers disagree. One review argues the RDA should be called a "recommended minimum intake" and that the best intake is higher.^[2] Another group of researchers says at least 1.2 to 1.6 g/kg a day is a more ideal target for adults.^[6]

A newer lab method also points higher. In a study of 8 healthy young men, it put the RDA-level need at 1.2 g/kg a day, 50% above the current RDA.^[7] That study had only 8 men, and raising the RDA is an argument some researchers make.^{[7, 2]}

What the 2025–2030 Dietary Guidelines say

The newest Dietary Guidelines for Americans came out in January 2026.^[3] They set protein goals of 1.2 to 1.6 grams per kilogram of body weight a day, adjusted to your calorie needs.^[3] That is well above the 0.8 g/kg RDA, and the two numbers do different jobs.^{[1, 8]}

The Guidelines' scientific report says the RDA was set to prevent deficiency.^[8] It says the RDA does not reflect what it takes to keep the most muscle in every case.^[8]

The report describes the RDA and the 10% to 35% range as complementary: one prevents deficiency, the other marks a range of intakes compatible with health.^[8] It places 1.2 to 1.6 g/kg inside that range, and says people who are physically active should aim for an upper limit of 1.4 to 1.6 g/kg.^[8] That cap sits at the low end of the 1.4 to 2.0 g/kg range from the sports nutrition society below.^{[8, 9]}

The evidence behind the new goal is a review of 30 trials.^[8] Higher-protein diets led to 1.31 kg more fat loss and 0.81 kg more lean mass kept.^[8]

Most of those trials were in adults with overweight or obesity who were cutting calories, with several smaller ones in adults whose weight was stable.^[8] The goal itself is written for the general public, so the evidence and the advice do not cover quite the same people.^{[3, 8]} The report still calls 0.8 g/kg the current RDA, and puts the average US adult at about 1 g/kg a day.^[8]

Protein for building muscle

The International Society of Sports Nutrition says 1.4 to 2.0 g/kg a day is enough for most people who exercise.^[9] It also suggests 20 to 40 g per serving, spread every 3 to 4 hours.^[9]

A 2018 meta-analysis of 49 studies with 1,863 people found that extra protein during weight training added 0.30 kg of fat-free mass on average.^[10] Gains stopped rising at about 1.62 g/kg a day, but the range around that estimate ran from 1.03 to 2.20, and the cutoff itself was not statistically significant.^[10] The authors concluded that training is a far stronger stimulus for strength than added protein.^[10]

A 2022 meta-analysis of 74 trials reached a similar answer: more protein gives small extra gains in lean mass for people doing resistance training.^[11]

While eating less to lose fat

The same sports nutrition society says 2.3 to 3.1 g/kg a day may be needed to keep lean mass in trained people who are eating less.^[9] In ordinary dieters, a review of 24 trials found higher-protein diets kept about 0.43 kg more fat-free mass, a modest benefit.^[12]

Protein for adults over 65

An expert group called PROT-AGE recommends at least 1.0 to 1.2 g/kg a day for adults over 65.^[13] It advises at least 1.2 g/kg for those who exercise, and 1.2 to 1.5 g/kg for most older adults with acute or chronic illness.^[13] A European group of experts (ESPEN) made the same core recommendations.^[14]

The trials are mixed. In 29 men over 70, a diet with twice the RDA for 10 weeks increased lean mass and leg power.^[15] But a review of 8 trials in frail older adults found that protein supplements alone did not improve muscle mass, strength or function.^[16] The 2018 meta-analysis also found that the muscle benefit of extra protein shrank with age.^[10]

Does it matter how you spread it out?

The evidence here is disputed. One study of 24 trained men found that 20 g every 3 hours built muscle protein faster over 12 hours than larger or smaller doses.^[17] A 2023 study found that 100 g at once gave a larger and longer response than 25 g, and the authors concluded the response has no upper limit.^[18]

Both studies measured short-term muscle building over hours, not muscle gained over months.^{[17, 18]} The PROT-AGE group said the evidence on timing is not yet strong enough for specific advice.^[13]

Is a high-protein diet safe?

In people with healthy kidneys, a review of trials found that kidney filtration changed about the same on higher- and lower-protein diets.^[19]

The sports nutrition society reports trials of up to one year at 2.5 to 3.3 g/kg a day in trained people that found no harm to kidney or liver markers.^[9] According to a review of the report behind the RDA, no upper limit for protein could be identified.^[2]

Kidney disease changes this. Some people with chronic kidney disease may need moderate amounts of protein so waste does not build up, while too little may lead to malnutrition.^[20] People on dialysis may need more protein.^[20]

For foods that get you there, see high-protein foods. For fitting protein into a full day of eating, see calories and macros, explained, how to count macros and body recomposition. The macro calculator gives a starting split in grams.

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