Your protein needs depend on your body weight, activity level, age, and goals. The baseline recommendation for healthy adults is 0.8 grams of protein per kilogram of body weight per day, which works out to about 46 grams for the average woman and 56 grams for the average man. But that number is a minimum to prevent deficiency, not an optimal target, and many people need significantly more.
Start With the Baseline Formula
The simplest way to estimate your protein needs is to multiply your body weight in kilograms by 0.8. If you think in pounds, divide your weight by 2.2 first. A 150-pound person (68 kg) would need at least 54 grams of protein per day under this formula. The acceptable range for protein as a percentage of total calories is 10 to 35 percent, giving you wide room to adjust based on your circumstances.
That 0.8 g/kg number is the Recommended Dietary Allowance, which represents the amount sufficient for about 97 percent of healthy, relatively inactive adults. It’s a floor, not a ceiling. If you exercise regularly, are over 65, are pregnant, or are trying to lose weight while preserving muscle, your needs climb well above this baseline.
Adjustments for Exercise and Muscle Goals
If you strength train or do endurance exercise regularly, a protein intake of 1.2 to 2.0 g/kg per day is a more appropriate range. The higher end applies to people training intensely or trying to build muscle, while the lower end suits those doing moderate recreational exercise. For a 170-pound (77 kg) person lifting weights several times a week, that translates to roughly 92 to 154 grams per day.
How you distribute that protein across the day matters too. Your muscles can only use so much protein at once for repair and growth. Research shows that roughly 30 grams of protein in a single meal is enough to maximally stimulate muscle building, and meals containing 30 to 45 grams produced the strongest associations with leg muscle mass and strength. Eating one large protein meal and skimping the rest of the day is less effective than spreading your intake across three or four meals.
The key trigger for muscle building is an amino acid called leucine, which is found in higher concentrations in animal proteins, soy, and some legumes. Older adults in particular benefit from hitting about 2,500 to 3,000 milligrams of leucine per meal, which roughly corresponds to that 25-to-30-gram protein serving. You don’t need to track leucine directly if you’re eating complete protein sources at each meal, but it’s worth knowing why that 30-gram-per-meal guideline exists.
Protein Needs After 65
Aging muscles become less responsive to protein. The same meal that triggers robust muscle repair in a 30-year-old produces a blunted response in a 70-year-old, which is one reason muscle loss accelerates with age. To counteract this, the PROT-AGE study group recommends that adults over 65 consume 1.0 to 1.2 g/kg of body weight per day as a baseline, rising to 1.2 g/kg or more for those who are physically active.
Older adults dealing with acute or chronic illness need even more, in the range of 1.2 to 1.5 g/kg per day, to support recovery and prevent further muscle breakdown. For a 140-pound (64 kg) older adult with a chronic condition, that means 77 to 96 grams daily, roughly double the standard RDA of 46 grams for women.
Protein During Weight Loss
When you cut calories, your body doesn’t just burn fat. It also breaks down muscle for energy, especially if protein intake is low. Eating more protein during a caloric deficit helps preserve lean mass so that most of the weight you lose comes from fat. Current recommendations for athletes losing weight call for 1.6 to 2.4 g/kg per day, and even non-athletes benefit from staying at the higher end of the protein range when dieting.
For a 180-pound (82 kg) person on a weight loss plan, that works out to roughly 131 to 197 grams per day. That’s a lot of protein, and hitting the top of that range requires intentional planning. Prioritizing a protein source at every meal and snack is the most practical strategy. The payoff is that you retain more muscle, keep your metabolism higher, and tend to feel fuller on fewer total calories.
Pregnancy and Breastfeeding
Protein needs increase gradually during pregnancy. In the first trimester, the additional requirement is negligible, roughly 1 extra gram per day. By the second trimester, you need about 9 additional grams daily above your normal intake. The third trimester is where demand peaks, with recommendations calling for an extra 28 to 31 grams per day on top of your pre-pregnancy needs.
During breastfeeding, the extra requirement is about 19 grams per day for the first six months of exclusive nursing, dropping to around 13 grams per day once you introduce solid foods. For most women, these increased needs can be met through a regular diet without supplements, as long as total calorie intake is adequate. Undereating overall is a more common problem than specifically undereating protein during this period.
Why Body Weight Alone Can Be Misleading
All of these calculations use total body weight, but protein is primarily needed by lean tissue (muscle, organs, bone) rather than fat tissue. For most people in a normal weight range, calculating from total body weight works fine. But if you carry a high percentage of body fat, using total weight can significantly overestimate your needs.
Research comparing protein calculations based on actual body weight versus fat-free mass found clinically meaningful differences in 78 to 100 percent of participants with overweight or obesity. A 280-pound person with 40 percent body fat has very different protein needs than a 280-pound person with 20 percent body fat, even though a simple weight-based formula would give them the same number.
If you know your body fat percentage from a DEXA scan, bioimpedance scale, or even a rough estimate, you can calculate your fat-free mass (total weight minus fat weight) and use 1.5 g per kilogram of fat-free mass instead. Alternatively, some people with obesity use an “adjusted body weight” that splits the difference between their actual weight and an ideal body weight. Either approach gives a more realistic target than plugging a very high body weight into a standard formula.
Putting It All Together
Here’s a quick reference for daily protein targets based on your situation:
- Healthy, mostly sedentary adult: 0.8 g/kg body weight
- Recreationally active adult: 1.2 to 1.6 g/kg
- Serious strength training or endurance athlete: 1.6 to 2.0 g/kg
- Adult over 65, generally healthy: 1.0 to 1.2 g/kg
- Adult over 65, active or managing illness: 1.2 to 1.5 g/kg
- Active adult in a caloric deficit: 1.6 to 2.4 g/kg
- Third trimester of pregnancy: baseline needs plus 28 to 31 g/day
- Breastfeeding (first 6 months): baseline needs plus 19 g/day
To convert these to actual grams, take your weight in pounds, divide by 2.2, and multiply by the appropriate g/kg number. Then divide your daily total by three or four meals, aiming for at least 25 to 30 grams per meal to make the most of each eating opportunity. If you have a high body fat percentage, consider using an adjusted weight or fat-free mass for your calculation instead of stepping on a scale and plugging in the raw number.
For healthy adults, high protein diets are not known to cause kidney damage or other medical problems. The concern about protein harming kidneys applies to people who already have compromised kidney function, not to the general population. If your kidneys are healthy, eating at the higher end of these ranges is safe.