Most healthy adults do well eating somewhere between 1.2 and 2.0 grams of protein per kilogram of body weight each day, though where you fall in that range depends on how active you are, whether you’re trying to lose fat or gain muscle, and how old you are. For a 70-kilogram (about 154-pound) person, that works out to roughly 84 to 140 grams per day. The standard government recommendation of 0.8 grams per kilogram is designed to prevent deficiency in sedentary people, not to optimize health, body composition, or performance. The real answer is more personal than a single number, and the science around protein needs has shifted considerably in recent years.
Why the Standard Recommendation Falls Short
The 0.8 g/kg/day figure you see on nutrition labels and in dietary guidelines represents the minimum intake needed to keep most sedentary adults from losing muscle over time. It was never intended as a target for anyone who exercises regularly, is trying to change their body composition, or is over 65. Think of it the way you’d think of the minimum passing grade on a test: it keeps you out of trouble, but it’s not something to aim for.
Researchers who study muscle protein synthesis, weight management, and aging have consistently arrived at higher numbers. Strength athletes, endurance runners, older adults, and people cutting calories all appear to benefit from intakes well above that 0.8 g/kg floor. The practical question isn’t “how little can I get away with?” but “how much do I actually need for what I’m trying to do?”
If You’re Trying to Build Muscle
For people engaged in regular resistance training, the range most supported by the literature is about 1.2 to 2.0 g/kg per day. A review in the Journal of the International Society of Sports Nutrition identified that range as one of the key nutritional requirements for maximizing muscle growth in weightlifters.1PubMed Central. Protein timing and its effects on muscular hypertrophy and strength in individuals engaged in weight-training Most strength-focused athletes land in the upper half of that range, around 1.6 to 2.0 g/kg, and there’s little evidence that going much higher yields additional muscle gains.
Endurance athletes have different demands but similarly elevated protein needs. A recent review in Sports Medicine concluded that endurance athletes should aim for about 1.8 g/kg per day, with the caveat that needs can climb above 2.0 g/kg during periods of restricted carbohydrate intake or on rest days when the body is focused on repair.2PubMed Central. Protein Nutrition for Endurance Athletes: A Metabolic Focus on Promoting Recovery and Training Adaptation A study using the indicator amino acid oxidation method found that the average protein requirement for endurance athletes after exercise was about 1.65 g/kg, with the recommended safe intake pegged at 1.83 g/kg.3PLOS ONE. Protein Requirements Are Elevated in Endurance Athletes after Exercise as Determined by the Indicator Amino Acid Oxidation Method
One thing the research has made clear: total daily protein matters more than when you eat it. A meta-analysis looking at protein timing around workouts found that total protein intake was the strongest predictor of muscle growth, and that consuming protein at a specific time relative to your training session didn’t make or break results.4PubMed Central. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis So if you’ve been stressing about chugging a shake within 30 minutes of your last set, you can relax. Just hit your daily number.
Protein During Weight Loss
When you’re eating fewer calories than you burn, your body doesn’t just tap fat for energy. It also breaks down muscle. This is where protein intake becomes especially important, because higher protein during a calorie deficit helps preserve muscle while the fat comes off. A review in Advances in Nutrition confirmed that high protein intake helps preserve lean body and muscle mass during weight loss.5PubMed Central. Preserving Healthy Muscle during Weight Loss
The most striking demonstration of this came from a trial that compared two groups of young men placed on a significant calorie deficit with intense exercise. The higher-protein group (about 2.4 g/kg/day) actually gained lean mass during the deficit while the control group’s lean mass stayed flat. On top of that, the high-protein group lost more fat: about 4.8 kg versus 3.5 kg.6The American Journal of Clinical Nutrition. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial That’s a remarkable result, gaining muscle while losing fat simultaneously, and it was driven by a combination of high protein and heavy exercise.
Very low-calorie diets deserve special mention. When calories are cut aggressively, the risk of muscle loss climbs sharply. Resistance exercise is the first priority for protecting muscle in that scenario, with adequate protein intake as the second.7PubMed Central. The impact and utility of very low-calorie diets: the role of exercise and protein in preserving skeletal muscle mass If you’re on a deep calorie cut, pushing protein toward the higher end of the range and lifting weights are your two best tools against muscle loss.
Why Protein Seems to Resist Turning Into Body Fat
One of the more counterintuitive findings in nutrition research is that overeating protein doesn’t produce the same weight gain as overeating carbohydrates or fat. A narrative review found that consuming a high-protein diet may not result in gains of body weight or fat mass, even when total calories exceed your normal intake.8PubMed Central. The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition – A Narrative Review A controlled overfeeding trial published in JAMA confirmed this in a more direct way: when people were overfed by about 1,000 extra calories a day, all three diet groups (low, normal, and high protein) gained roughly the same amount of body fat, but the higher-protein groups gained substantially more lean mass. Protein intake predicted lean mass gain but not fat storage.9JAMA. Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition During Overeating: A Randomized Controlled Trial
The likely explanation involves the thermic effect of food. Your body uses more energy to digest and process protein than it does for carbohydrates or fat. Protein’s thermic effect is roughly two to three times higher than that of the other macronutrients, meaning a good chunk of extra protein calories get burned off as heat rather than stored.
Protein Needs After 60
As you age, your muscles become less responsive to the protein you eat. Researchers call this “anabolic resistance,” and it means that the same serving of chicken or eggs that stimulated strong muscle-building in your 30s produces a blunted response in your 60s and beyond. Because of this, older adults generally require a greater protein intake to get the same muscle-building signal from a meal.10Advances in Nutrition. Keeping Older Muscle “Young” through Dietary Protein and Physical Activity
For older adults who already have sarcopenia (significant age-related loss of muscle mass and strength), the needs appear to be even higher. A 2025 study using the indicator amino acid oxidation technique concluded that older adults with sarcopenia may require more dietary protein than the current recommendations suggest, noting it was the first study to directly measure protein requirements in this specific group.11PubMed Central. Dietary protein requirements of older adults with sarcopenia determined by the indicator amino acid oxidation technology Most geriatric nutrition experts now suggest at least 1.0 to 1.2 g/kg per day as a minimum for healthy older adults, with higher amounts for those who are already losing muscle or are physically active.
Protein and Appetite
One reason high-protein diets tend to help with weight management, beyond their muscle-sparing effects, is that protein is the most satiating macronutrient. When you eat a high-protein meal, your gut releases more of the hormones that signal fullness to your brain. Protein stimulates the release of hormones like GLP-1 and cholecystokinin from cells in the intestinal lining.12PubMed Central. High Protein Intake Stimulates Postprandial GLP1 and PYY Release These hormones slow gastric emptying and dial down hunger.
A systematic review and meta-analysis of randomized controlled trials found that protein consumption led to a decrease in ghrelin (the hunger hormone) and increases in cholecystokinin and GLP-1. These appetite-regulating effects were present at lower protein doses but became significantly stronger at doses of 35 grams or more per serving.13PubMed. Effect of short- and long-term protein consumption on appetite and appetite-regulating gastrointestinal hormones, a systematic review and meta-analysis of randomized controlled trials That roughly 35-gram threshold is a useful benchmark if you’re trying to make meals more satisfying: it’s about the amount in a palm-sized portion of meat, a cup of Greek yogurt, or a generous scoop of protein powder mixed with milk.
Plant Protein vs. Animal Protein
Not all protein sources are equally effective at stimulating muscle growth. Animal proteins, such as meat, dairy, and eggs, tend to have higher digestibility and a more complete amino acid profile, particularly when it comes to leucine, the amino acid most important for triggering muscle protein synthesis. Plant-based proteins are generally lower in essential amino acids and contain less leucine, which means plant amino acids are more likely to be used for energy rather than muscle building.14PubMed Central. The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review Plant proteins can also contain compounds that reduce how much protein your body actually absorbs.15PubMed Central. Protein Nutrition: Understanding Structure, Digestibility, and Bioavailability for Optimal Health
This doesn’t mean a plant-based diet can’t deliver adequate protein for muscle maintenance or even athletic performance. It just requires more intentional planning. Modeling studies have shown that completely plant-based diets, when designed to meet energy needs and spread across multiple meals, can reach sufficient leucine thresholds. One study modeled plant-based meal plans for adult male rugby players and found that eating four meals a day could provide about 2.9 grams of leucine per meal, meeting the targets.16PubMed Central. Protein and Leucine Requirements for Maximal Muscular Development and Athletic Performance Are Achieved with Completely Plant-Based Diets Modeled to Meet Energy Needs in Adult Male Rugby Players The practical takeaway: if you eat mostly or entirely plants, aim for the higher end of protein recommendations, combine different plant protein sources across the day, and consider soy, pea, or other legume-based proteins that are relatively leucine-rich.
Pregnancy and Lactation
Protein needs climb during pregnancy and breastfeeding, and the standard recommendations may underestimate how much is needed. A study using the indicator amino acid oxidation method found that protein requirements during late pregnancy (around 36 weeks) were about 1.52 g/kg per day, well above the general adult recommendation.17PubMed Central. Protein Requirements of Healthy Lactating Women Are Higher Than the Current Recommendations Lactating women showed similarly elevated needs. These numbers suggest that the typical dietary advice given to pregnant and breastfeeding women may leave them short, particularly if they’re also active.
Will Too Much Protein Hurt Your Kidneys?
This is one of the most persistent concerns about high-protein diets, and the answer is more nuanced than the internet usually allows. High dietary protein intake does increase the kidneys’ workload by raising the rate at which they filter blood. A review in the Journal of the American Society of Nephrology noted that high-protein diets can cause kidney hyperfiltration and may worsen function in people who already have impaired kidneys, and raised the possibility that long-term high intake could even contribute to new kidney disease.18PubMed Central. The Effects of High-Protein Diets on Kidney Health and Longevity
However, an earlier review looking at centuries of high-protein Western diets found no significant evidence that high protein intake damages kidney function in healthy people.19PubMed Central. Dietary protein intake and renal function The distinction matters: if your kidneys are healthy, there’s no strong evidence that a high-protein diet will harm them. If you already have chronic kidney disease or reduced kidney function, excess protein is a legitimate concern and restricting it is standard medical advice. The safest approach for anyone with kidney concerns is to get checked and talk to a doctor before pushing protein intake aggressively.
The Bone Health Question
An older concern held that high-protein diets leach calcium from bones, potentially increasing the risk of osteoporosis. This idea came from the observation that protein increases calcium excretion in urine. But the story turns out to be more complicated. A review in Nutrients found that while high protein intake does cause some extra calcium in the urine, it simultaneously increases calcium absorption in the gut, and any spike in urinary calcium is transient, typically normalizing within about three weeks.20PubMed Central. Impact of Dietary Protein on Osteoporosis Development Excessive calcium excretion from high protein intake does not appear to cause bone mineral loss.
In fact, the evidence leans the other way. Epidemiological studies show that greater protein intake tends to be beneficial for bone health in adults, and this effect is enhanced when calcium intake is also adequate. Protein may support bones by increasing muscle mass (which exerts mechanical force on bone), increasing calcium absorption, and stimulating the production of growth factors like IGF-1.21PubMed Central. Dietary protein is beneficial to bone health under conditions of adequate calcium intake: an update on clinical research So the old “protein is bad for your bones” narrative has largely been put to rest, with the caveat that adequate calcium matters too.
What Happens in Your Gut at High Intakes
One area that gets less attention is what high protein does further down the digestive tract. When you eat more protein than your small intestine can fully absorb, the undigested portion reaches the large intestine, where gut bacteria ferment it. This fermentation produces a mix of metabolites including ammonia, hydrogen sulfide, and phenolic compounds.22PubMed. Protein fermentation in the gut; implications for intestinal dysfunction in humans, pigs, and poultry Some of these byproducts are potentially harmful: they’ve been linked to increased inflammation, greater tissue permeability in the gut, and in some research, even a higher risk of colorectal cancer development.23PubMed Central. Microbial Fermentation of Dietary Protein: An Important Factor in Diet⁻Microbe⁻Host Interaction
The amount of undigested protein reaching the colon increases with the amount you eat. A systematic review confirmed that as dietary protein intake goes up, so does the substrate available for proteolytic fermentation, shifting the gut environment in potentially unfavorable ways.24PubMed Central. Effect of Dietary Protein and Processing on Gut Microbiota—A Systematic Review This doesn’t mean moderate protein intake is harmful to your gut, but it’s one reason that extremely high intakes (north of 3 g/kg per day, for instance) may carry hidden costs that don’t show up in short-term body composition studies. Eating plenty of fiber alongside your protein likely helps by giving gut bacteria a preferred fuel source, nudging fermentation away from protein and toward carbohydrate substrates.
The Environmental Dimension of Protein Choices
How much protein you eat matters, but so does where it comes from, particularly if you care about the environmental footprint of your diet. A study published in Science of The Total Environment identified five distinct dietary protein profiles and found that the profile with the lowest contribution from meat had the lowest impact on nearly all environmental indicators, including greenhouse gas emissions, and also carried the lowest long-term health risk. On the other end, the profile dominated by ruminant meat (beef and lamb) had the highest environmental pressures across most indicators.25PubMed. Dietary protein consumption profiles show contrasting impacts on environmental and health indicators
This doesn’t mean you need to go fully plant-based to reduce your impact. Even shifting a portion of your protein from beef and lamb toward poultry, fish, dairy, legumes, or soy makes a meaningful difference. For people aiming at higher protein intakes for athletic or health reasons, leaning on a mix of animal and plant sources rather than relying heavily on red meat represents a workable middle ground.
What Hunter-Gatherers Ate, for Context
It can be useful to zoom out and look at protein intake through an evolutionary lens. An analysis of worldwide hunter-gatherer diets found that protein typically supplied about 19 to 35 percent of total calories in these populations, with most societies deriving over half their food energy from animal sources whenever the local ecology allowed it.26The American Journal of Clinical Nutrition. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets That translates to something like 95 to 175 grams of protein per day on a 2,000-calorie diet. A more recent review noted that the plant-to-animal food balance among warm-climate hunter-gatherers averages around 50/50, with enormous variation depending on geography: arctic populations ate far more animal food, while groups in the tropics or those who practiced some farming ate more plants.27PubMed. Effects of Evolution, Ecology, and Economy on Human Diet: Insights from Hunter-Gatherers and Other Small-Scale Societies
None of this proves that modern humans should eat like hunter-gatherers, since our activity levels, lifespans, and health challenges differ substantially. But it does suggest that the human body evolved handling protein intakes much higher than the 0.8 g/kg minimum, and that the 1.2-to-2.0 g/kg range supported by current research sits comfortably within the range our species has eaten for most of its history.