How to Find How Much Protein You Need Each Day

Your daily protein need depends on your body weight, activity level, age, and goals, but the starting point for most healthy adults is somewhere between 0.8 and 1.2 grams per kilogram of body weight per day. That range sounds simple enough, yet the “official” number on the lower end was set two decades ago using methods that newer research suggests may underestimate what your body actually uses. For anyone who exercises regularly, is trying to lose fat without losing muscle, is pregnant, or is over about 65, the number climbs higher still. Getting to your personal target means understanding which of these factors apply to you and how much each one shifts the math.

The Baseline Number and Why It Is Probably Too Low

The Recommended Dietary Allowance for protein in the United States and Canada is 0.8 grams per kilogram of body weight per day for healthy adults. That figure was published in 2005 and has not been updated since, despite a growing body of research questioning whether it captures what the body actually needs.¹ The RDA was derived primarily from nitrogen balance studies, which measure how much nitrogen enters and leaves the body. The idea is straightforward: if nitrogen in equals nitrogen out, you are eating enough protein. But nitrogen balance has well-documented blind spots. It tends to overestimate intake and underestimate losses, which means it can declare you “balanced” at a protein level that is actually below what would maximize your body’s ability to build and repair tissue.

A newer technique, called the indicator amino acid oxidation method, consistently produces higher estimates. A recent umbrella review and meta-analysis comparing the two approaches found that in non-athletes, the requirement measured by this newer method was about 36 percent higher than the nitrogen balance estimate. In athletes, it was about 27 percent higher.² That said, some researchers caution that the newer method may be measuring something subtly different: not the bare minimum to avoid deficiency, but the intake that maximizes your body’s anabolic response.³ In other words, the “requirement” and the “optimal intake” may be two different things. For a practical starting point, though, most people eating around 0.8 g/kg are likely getting enough to avoid clinical deficiency but may not be getting enough to feel, perform, or recover at their best.

How Exercise Changes the Target

If you lift weights, your protein needs go up. Research on people engaged in resistance training consistently recommends a range of roughly 1.2 to 2.0 grams per kilogram of body weight per day to support muscle growth and repair.⁴ That is a wide range because individual variation matters: someone just starting a lifting program probably does fine near the lower end, while a competitive athlete in a hard training block may benefit from the upper end.

Endurance athletes have their own set of numbers. For casual joggers and people doing moderate cardio, protein needs do not rise much above those of someone who is sedentary. But for serious endurance athletes, the picture shifts. One study using the indicator amino acid oxidation method found that the average protein requirement after endurance exercise was about 1.65 g/kg/day, with a recommended intake of roughly 1.83 g/kg/day to cover most individuals.⁵ A 2025 review went further, advocating for about 1.8 g/kg/day for endurance athletes and noting that the requirement may exceed 2.0 g/kg/day during periods of restricted carbohydrate intake or on rest days.⁶ An older review drew a more conservative boundary, placing the maximum at about 1.6 g/kg/day for top-level athletes and noting that moderate-intensity activity does not raise protein needs much at all, as long as you are eating enough total calories and carbohydrates.⁷

The practical takeaway: if you exercise regularly at any serious intensity, somewhere between 1.2 and 2.0 g/kg/day is a well-supported range. Where you land within it depends on your sport, how hard you are training, and whether you are eating enough overall.

Your Body Weight Is the Wrong Starting Point Sometimes

All of these recommendations are expressed in grams per kilogram of body weight, which works well for people at a roughly average weight. But if you are carrying a lot of extra fat or if you are significantly underweight, using your total body weight can skew the calculation. Fat tissue does not have the same protein demands as muscle. A person at 130 kilograms with a high body-fat percentage does not need twice the protein of a person at 65 kilograms who is mostly lean.

Research comparing protein calculations based on total body weight versus fat-free mass found clinically meaningful differences for most people with overweight or obesity. Using an adjusted or “corrected” body weight overestimated protein needs in a large share of participants with overweight or healthy weight, and underestimated needs in some with severe obesity.⁸ Similarly, a study of masters athletes found that when protein intake was indexed to lean body mass rather than total body weight, the apparent gap between men’s and women’s needs largely disappeared, suggesting that lean mass is the more relevant reference point.⁹

If you have a rough sense of your lean mass (from a DEXA scan, a body-fat scale, or even a visual estimate), you can use that number instead. If not, a common shortcut for people at higher body weights is to base the calculation on a “goal” or “ideal” body weight rather than actual weight. This avoids dramatically overshoot protein targets because of fat mass that does not need to be fed like muscle.

Losing Weight Without Losing Muscle

When you eat fewer calories than you burn, your body does not exclusively dip into fat reserves. It also breaks down some muscle, especially if protein intake is low or you are not doing any resistance exercise. Bumping protein higher during a calorie deficit is one of the most effective ways to protect lean mass. A systematic review and meta-analysis of studies in adults with overweight or obesity found that intakes above about 1.3 g/kg/day were associated with increases in muscle mass during weight loss, while intakes below 1.0 g/kg/day were linked to a higher risk of muscle loss.¹⁰ Earlier work on weight-loss diets supported using protein at levels above 1.5 g/kg/day for the best results, partly because of the amino acid leucine’s role in stimulating muscle repair.¹¹

Even in very-low-calorie diets, maintaining adequate protein and adding resistance exercise are the two most important factors for holding on to muscle.¹² If weight loss is your goal, the calculation shifts upward compared to someone eating at maintenance, and combining higher protein with strength training gives you the best shot at losing fat while keeping the muscle you already have.

Aging and the “Anabolic Resistance” Problem

As you get older, your muscles become less responsive to the protein you eat. The same meal that would trigger a strong muscle-building response in a 25-year-old produces a blunted response in a 70-year-old. This phenomenon, known as anabolic resistance, is one of the drivers behind age-related muscle loss.¹³ The practical consequence is that older adults need more protein per meal and per day to achieve the same muscle-preserving effect.

Many geriatric nutrition experts recommend that adults over 65 aim for at least 1.0 to 1.2 g/kg/day, and higher if they are dealing with illness, recovering from surgery, or exercising regularly. The standard RDA of 0.8 g/kg/day is increasingly viewed as insufficient for this age group. Because anabolic resistance can also be partially offset by resistance exercise and by concentrating protein into meals with enough leucine to cross the threshold that triggers muscle repair, older adults benefit from both eating more protein overall and being strategic about how they distribute it.

Pregnancy and Breastfeeding

The current Estimated Average Requirement for protein during lactation is 1.05 g/kg/day, but studies using the indicator amino acid oxidation method have found that actual needs are higher. One study measured protein requirements during breastfeeding and concluded they exceeded the official recommendation, consistent with earlier findings that late pregnancy requires about 1.52 g/kg/day.¹⁴ When estimated as an absolute increment, the protein cost of producing breast milk comes to roughly 15 to 20 grams per day on top of baseline needs, depending on whether you factor in the non-protein nitrogen present in human milk.¹⁵

The broader systematic review of protein requirements across the lifecycle flagged pregnancy, lactation, infancy, childhood, and adolescence as life stages where evidence is particularly thin.¹ If you are pregnant or nursing, the safest approach is to eat well above the generic adult RDA, and working with a dietitian to dial in the number makes sense given the limited research.

Spreading Protein Across the Day

Once you have a daily target, the question becomes how to split it up. The popular belief that your body can only “use” about 20 to 25 grams of protein at a sitting is a simplification. That figure comes from studies measuring muscle protein synthesis in young adults after a single dose of protein, and it represents the point at which the rate of synthesis plateaus in that immediate window. But not all of the extra protein beyond that threshold is wasted; some of it goes to other tissues and processes.¹⁶

A practical guideline from the same review suggests aiming for about 0.4 g/kg per meal spread over at least four meals to hit a daily minimum of 1.6 g/kg. For someone at 80 kilograms, that is roughly 32 grams per meal, four times a day. If your target is higher, scaling up to about 0.55 g/kg per meal across four sittings gets you to the upper end of about 2.2 g/kg/day.¹⁶ The main point is that distributing protein relatively evenly is better for muscle synthesis than loading it all into one or two meals, which is a pattern many people fall into by eating a protein-light breakfast and lunch followed by a large dinner.

Not All Protein Is Created Equal

The source of your protein affects how much of it your body can actually use. Animal-derived proteins like eggs, dairy, meat, and fish deliver all the essential amino acids in proportions closely matching human requirements and are highly digestible. Plant-sourced proteins are generally lower in certain amino acids, especially lysine and leucine, and their digestibility varies widely depending on the food and how it is processed.

A study of 193 vegans in New Zealand found that while most met the crude Estimated Average Requirement for total protein, once the researchers adjusted for the digestibility of each amino acid, only about half the group met requirements for lysine and leucine.¹⁷ Commercially available plant-based meat and dairy substitutes have the same limitation: they tend to contain less protein than their animal-based counterparts and often have incomplete amino acid profiles.¹⁸

The older protein-quality scoring system, PDCAAS, has been gradually replaced in research circles by a newer one, DIAAS, which measures the digestibility of individual amino acids at the small intestine rather than using an overall fecal nitrogen number. DIAAS tends to give animal proteins slightly higher marks and some plant proteins lower marks compared to PDCAAS, because the older method could overestimate protein quality for certain plant sources.¹⁹ The difference between the two scoring systems exceeded 13 percent for several protein sources in one head-to-head comparison.²⁰

None of this means you cannot meet your needs on a plant-based diet. It means you have to eat a bit more total protein and combine sources throughout the day (legumes with grains, for instance) to make sure you are covering the amino acids that individual plant foods lack. If you eat a mixed diet with at least some animal protein, this is mostly a non-issue.

High Protein and Your Kidneys

One worry that comes up whenever people push protein higher is kidney damage. The evidence here splits cleanly along one line: whether your kidneys are already healthy or not. In people with normal kidney function, high-protein diets have not been shown to cause kidney disease. A review in the American Journal of Kidney Diseases concluded that there are no clear kidney-related reasons to avoid high-protein diets in healthy individuals, though the theoretical risks should be discussed.²¹

The picture reverses sharply for people with existing chronic kidney disease. High protein intake can increase pressure inside the kidney’s filtering units, potentially accelerating damage and protein leakage into the urine.²² If you have any kidney issues or are at elevated risk because of diabetes or high blood pressure, a conversation with your doctor before increasing protein is genuinely important, not just a boilerplate disclaimer.

Protein’s Effect on Hunger and Overeating

One reason higher-protein diets keep coming up in weight-management conversations is that protein is the most satiating macronutrient. Part of the mechanism involves gut hormones. A high-protein meal triggers a stronger release of the appetite-suppressing hormones GLP-1 and PYY compared to meals high in fat or carbohydrates.²³ At the same time, protein tends to lower ghrelin, the hormone that drives hunger.²⁴

The protein leverage hypothesis adds an evolutionary angle to this. The idea is that humans have a particularly strong appetite for protein specifically, and when the protein percentage of the diet drops (as it does in heavily processed modern food environments), people compensate by eating more total food in an unconscious attempt to hit their protein target.²⁵ In other words, when your diet is diluted with calorie-dense but protein-poor foods, you may keep eating past the point of caloric need because your protein appetite is not satisfied yet.²⁶ Whether or not the hypothesis fully explains modern obesity trends, the satiety benefit of protein is well established and worth considering when you are planning meals.

What Happens in Your Gut at Very High Intakes

There is a less-discussed downside to pushing protein very high. Not all the protein you eat gets absorbed in the small intestine. Whatever escapes digestion there travels to the large intestine, where gut bacteria ferment it. This fermentation produces metabolites like ammonia, phenols, indoles, and sulfides, some of which can irritate the intestinal lining.²⁷ The higher the protein content of the diet, the more undigested protein reaches the colon, and the more these potentially harmful byproducts accumulate.²⁸

This does not mean a high-protein diet is bad for your gut, but it does suggest that pairing higher protein with adequate fiber is a smart move. Fiber feeds the beneficial bacteria in your colon and promotes the production of short-chain fatty acids, which counterbalance some of the negative effects of protein fermentation. The people most likely to run into gut issues are those eating very high protein with very low fiber, which is a common pattern on restrictive low-carb diets.

How Accurate Is Your Tracking

Knowing your target is one thing. Knowing how much protein you are actually eating is another, and the tools most people use are not as reliable as they seem. A study comparing MyFitnessPal records to 24-hour dietary recalls found that the app significantly underestimated energy intake and all macronutrients.²⁹ A broader meta-analysis of dietary record apps found that protein intake was underreported by an average of about 12 grams per day.³⁰ Part of the problem is user error: forgotten snacks, inaccurate portion estimates, choosing the wrong database entry. Part of it is the databases themselves, which contain crowd-sourced entries of varying accuracy.

Research-grade dietary tools are not much better in everyday use. The ASA24, a tool developed by the National Cancer Institute, still showed underreporting of energy intake relative to objective biomarkers, though protein estimates were somewhat closer to recovery biomarkers for women.³¹ The implication is practical: if you are using an app and consistently landing right at your target, there is a decent chance you are actually a bit under it. Building in a small buffer, or occasionally weighing portions to calibrate your eye, can help close the gap.

A Quick Way to Find Your Number

Pulling all of this together, here is a rough framework. Multiply your weight in kilograms by the factor that best fits your situation:

Sedentary adult: 0.8 to 1.0 g/kg/day, which is the minimum to avoid deficiency. Many researchers now argue the floor should be closer to 1.0 to 1.2.
Recreationally active: 1.2 to 1.6 g/kg/day, covering moderate exercise and general fitness.
Strength or endurance athlete: 1.6 to 2.2 g/kg/day, with the higher end for heavy training or competition phases.
Losing weight actively: at least 1.3 g/kg/day, and often 1.5 or higher to protect muscle during a calorie deficit.
Over 65: at least 1.0 to 1.2 g/kg/day at minimum, higher with regular exercise.
Pregnant or breastfeeding: around 1.2 to 1.5 g/kg/day, based on the limited evidence suggesting needs are above current guidelines.

If you are significantly overweight, use a goal or adjusted body weight rather than your actual weight, or estimate your lean mass and multiply by a slightly higher factor. If your diet is entirely plant-based, consider adding roughly 10 to 20 percent more total protein to compensate for lower digestibility and amino acid gaps in plant sources. And if you are trying to hit the upper end of any range, spreading your intake across at least four meals gives your body the best opportunity to use what you eat for repair and growth rather than simply burning it for energy.