Your ideal daily protein intake depends on your body weight, activity level, and goals, but the starting point is simple: multiply your weight in kilograms by a number between 0.8 and 2.2. A sedentary adult needs about 0.8 grams of protein per kilogram of body weight per day. That’s the international Recommended Dietary Allowance, and for a 75 kg (165 lb) person, it works out to roughly 60 grams. But if you exercise, want to lose fat without losing muscle, or are over 65, you likely need significantly more.
The Quick Formula
To estimate your needs, start by converting your weight to kilograms (divide your weight in pounds by 2.2). Then multiply by the factor that fits your situation:
- Sedentary adult: 0.8 g/kg per day
- Recreationally active: 1.0–1.4 g/kg per day
- Endurance training: 1.0–1.6 g/kg per day
- Strength or power training: 1.6–2.0 g/kg per day
- Losing weight while preserving muscle: 1.2–1.6 g/kg per day
So a 180 lb person (about 82 kg) who lifts weights would aim for roughly 131 to 164 grams of protein per day. That same person, if sedentary, would technically meet the minimum at just 66 grams.
Why the Standard RDA Is a Floor, Not a Target
The RDA of 0.8 g/kg was designed to prevent deficiency in 97–98% of the population. It’s the amount needed to avoid negative nitrogen balance, which essentially means your body isn’t breaking down more protein than it’s building. That’s a survival threshold, not an optimal intake for someone trying to build muscle, stay strong as they age, or lose fat effectively.
Most sports nutrition research places the practical range for active people between 1.2 and 2.2 g/kg per day. The International Society of Sports Nutrition recommends up to 2.0 g/kg for strength and power athletes, with endurance athletes needing somewhat less at 1.0 to 1.6 g/kg depending on training intensity and experience level.
Protein Needs During Weight Loss
When you eat fewer calories than you burn, your body doesn’t just pull energy from fat stores. It also breaks down muscle tissue unless you give it enough protein to work with. Research shows that intakes below 1.0 g/kg per day during a calorie deficit are associated with a higher risk of losing muscle mass. An intake exceeding 1.3 g/kg per day, on the other hand, is associated with actually gaining muscle even while losing weight overall.
Studies comparing normal protein diets (0.8 g/kg) to higher protein diets (1.2–1.6 g/kg) during weight loss consistently show better preservation of lean mass and improved body composition with the higher intake. For a 170 lb person cutting calories, that translates to roughly 93 to 124 grams of protein per day rather than the bare-minimum 62 grams.
How Much Protein Per Meal Matters
Your body doesn’t just care about how much protein you eat in a day. How you distribute it across meals affects how well your muscles can use it. Research suggests aiming for about 0.4 g/kg per meal spread across at least four meals to maximize muscle protein synthesis. For that same 82 kg person, that’s roughly 33 grams per meal.
There’s also a practical ceiling per sitting. Consuming more than about 0.55 g/kg in a single meal (around 45 grams for an 82 kg person) doesn’t appear to stimulate additional muscle building, though the extra protein still provides calories and can be used for other bodily functions. The key takeaway: eating 130 grams of protein in two large meals is less effective for muscle maintenance than spreading it across four meals of roughly 33 grams each.
Adjustments for Age
Aging muscles become less responsive to protein. Younger adults can trigger muscle protein synthesis with relatively small amounts of essential amino acids, but older adults need a larger dose to get the same response. Specifically, small servings of around 7.5 grams of essential amino acids (the amount in roughly 15 grams of protein) fail to stimulate muscle building in older adults, while they work fine in younger people.
To compensate, adults over 65 should aim for 25 to 30 grams of high-quality protein at each meal rather than spreading smaller amounts throughout the day. This per-meal threshold maximally stimulates muscle protein synthesis in both younger and older individuals, but it’s especially critical for older adults because falling short at any given meal represents a missed opportunity that their bodies can’t easily make up for later. Over time, consistently low protein meals contribute to sarcopenia, the gradual loss of muscle mass and strength that accelerates after 65.
Pregnancy and Breastfeeding
Protein needs increase during pregnancy, but not as dramatically as you might expect in the early stages. During the first trimester, the additional requirement is only about 1 gram per day above your normal needs. In the second and third trimesters, that jumps to an additional 21 grams per day. For a moderately active pregnant woman weighing 68 kg (150 lbs), that means going from roughly 55–75 grams per day to about 76–96 grams in later pregnancy.
Total Body Weight vs. Lean Body Mass
All of the standard recommendations are based on total body weight, which works reasonably well for people at a healthy weight. But if you’re carrying significant extra body fat, using total weight can overestimate your needs since fat tissue doesn’t require protein the way muscle does. Some researchers argue that lean body mass (everything in your body except fat) provides a more accurate basis for protein calculations.
The challenge is that most people don’t know their lean body mass. The most accurate way to measure it is through a DEXA scan, which isn’t something most people have easy access to. A practical workaround: if you’re significantly overweight, use your goal body weight or an estimated “ideal” weight for your height instead of your current weight. If you’re at a relatively normal body fat percentage, total body weight works fine and is much simpler.
Is Too Much Protein Dangerous?
For healthy people with two functioning kidneys, intakes up to 2.0 g/kg per day are well studied and considered safe. Most definitions classify anything above 1.5 g/kg as a “high protein” diet. People with a single kidney should generally stay below 1.2 g/kg per day, as the remaining kidney handles all the filtering work and excessive protein increases its workload.
The idea that high protein diets damage healthy kidneys persists, but the evidence doesn’t support it for people without pre-existing kidney disease. That said, there’s a difference between “not harmful” and “more is better.” Beyond about 2.2 g/kg per day, the research shows diminishing returns for muscle building, and the extra calories from protein still count toward your total energy intake.
Putting It All Together
Here’s a worked example. Say you weigh 155 lbs (70 kg), you strength train three days a week, and you’re trying to slowly lose some body fat. Your target range would be 1.6 g/kg per day on the higher end, giving you about 112 grams daily. Split that across four meals and you’re looking at 28 grams per meal, which is roughly a palm-sized portion of chicken, a cup of Greek yogurt with some nuts, or a large serving of lentils with rice. Track for a week or two to calibrate your eye for portion sizes, then adjust based on how your body responds.