The RDA for protein is 0.8 grams per kilogram of body weight per day for healthy adults, which works out to about 0.36 grams per pound. For a 150-pound person, that’s roughly 54 grams of protein daily. But this number represents the minimum to prevent deficiency, not necessarily the amount that keeps you in peak health, and many nutrition researchers now argue it’s too low for several groups.
How to Calculate Your RDA
The math is straightforward. Take your weight in pounds and multiply by 0.36, or take your weight in kilograms and multiply by 0.8. A 180-pound (82 kg) person lands at about 65 grams per day. A 130-pound (59 kg) person needs around 47 grams.
These figures come from the 2005 Dietary Reference Intakes, which remain the official U.S. and Canadian guidelines. The National Academies has acknowledged that an update to the macronutrient DRIs is overdue and is currently under consideration, but no revision has been published yet.
What the RDA Actually Measures
Your body constantly breaks down and rebuilds proteins. Several times more protein is recycled inside your body each day than you eat, but that recycling isn’t perfectly efficient. Small amounts of amino acids are lost through urine, feces, sweat, shed skin, hair, and nails. The RDA is calculated to replace those losses and keep you in “nitrogen balance,” meaning you’re not losing more protein than you’re taking in.
The baseline for this calculation comes from studies of people fed protein-free diets. Across more than 200 adults aged 20 to 77, obligatory nitrogen losses averaged about 53 milligrams of nitrogen per kilogram per day, a figure that’s remarkably consistent across body sizes and ages. The RDA adds a safety margin on top of the average requirement (0.61 g/kg/day) to cover 97.5% of the population, landing at 0.8 g/kg/day.
Amino acids you eat beyond what your body needs for building and repair aren’t stored as protein. Instead, the nitrogen gets stripped off and excreted as urea, and the remaining carbon skeleton is burned for energy or converted into carbohydrate or fat.
Why Many Experts Say 0.8 g/kg Is Too Low
The RDA prevents clinical protein deficiency. It was never designed to optimize muscle mass, physical performance, or long-term health. A growing body of research suggests that eating closer to 1.0 to 1.6 g/kg per day offers meaningful benefits, especially for people who exercise regularly, are trying to lose weight while preserving muscle, or are over 65.
The distinction matters most for older adults. Muscle mass naturally declines with age, a process called sarcopenia, and the 0.8 g/kg target appears insufficient to slow it. An international expert panel has recommended that adults over 65 aim for 1.0 to 1.2 g/kg per day as a baseline, with intakes up to 1.3 g/kg for those doing resistance exercise and 1.2 to 1.5 g/kg for those managing acute or chronic illness. For a 160-pound older adult, that translates to roughly 73 to 87 grams daily rather than the 58 grams the standard RDA would suggest.
Requirements for Children and Teens
Children need more protein per kilogram than adults because they’re building new tissue, not just maintaining it. Current recommendations based on nitrogen balance studies are:
- Infants 7 to 12 months: 1.2 g/kg/day
- Toddlers 1 to 3 years: 1.05 g/kg/day
- Children 4 to 8 years: 0.95 g/kg/day
- Children 9 to 13 years: 0.95 g/kg/day
- Teens 14 to 18 years: 0.85 g/kg/day
Newer research using more sensitive measurement techniques suggests these numbers may also be underestimates. Studies using stable isotope methods put the requirement for children aged 6 to 10 closer to 1.55 g/kg/day, nearly double the current RDA for that age group.
Protein Needs During Pregnancy and Breastfeeding
Pregnancy increases protein demands substantially, and the increase isn’t uniform across trimesters. Recent research using precise amino acid tracking found that pregnant women need about 1.2 g/kg/day during early pregnancy (around 16 weeks) and approximately 1.52 g/kg/day in late pregnancy (around 36 weeks). For a 150-pound woman, that’s roughly 82 grams in the first trimester climbing to about 103 grams by the third. These figures are notably higher than older estimates, which placed the increase at just 25 extra grams per day.
Upper Limits and Safety
There is no official tolerable upper intake level for protein, but research has mapped out a practical safety range. Long-term intake of up to 2 g/kg/day is considered safe for healthy adults. The tolerable ceiling is around 3.5 g/kg/day for people who have gradually adapted to high protein diets, though chronically exceeding 2 g/kg/day has been linked to digestive issues, kidney strain, and vascular problems in some studies.
For most people, the realistic concern isn’t eating too much protein. It’s eating too little, particularly if you’re older, very active, or relying heavily on plant-based sources that are less protein-dense per serving.
What Common Foods Provide
Hitting your protein target is easier when you know the ballpark numbers for everyday foods:
- One egg: 6 grams
- One ounce of chicken, beef, pork, or turkey: 7 grams (a typical 4-ounce serving gives you about 28 grams)
- Half cup of cooked lentils: 9 grams
- 5 ounces of plain Greek yogurt: 12 to 18 grams
A person aiming for 60 grams of protein daily could get there with two eggs at breakfast (12 g), a cup of lentil soup at lunch (18 g), a container of Greek yogurt as a snack (15 g), and a 3-ounce portion of chicken at dinner (21 g). Spreading protein across meals rather than loading it into one sitting also helps your body use it more efficiently, since there’s a practical limit to how much muscle-building stimulus a single meal can trigger.