Protein
Protein supplies the amino acids the body uses to build and repair muscle, skin, and organs, and to make enzymes, hormones, and antibodies. The RDA is 0.8 g per kg of body weight for adults, and the acceptable range is 10 to 35 percent of daily calories. Active people, older adults, and those recovering from illness often need more.
Why it matters
What it does in your body
- Builds and repairs muscle and tissue
- Forms enzymes and hormones
- Makes immune antibodies
- Transports nutrients and oxygen in the blood
- Provides amino acids that cannot be stored
By age, sex, and life stage
How much you need
The protein RDA is 0.8 g per kg body weight for adults, which is about 56 g/day for a reference man and 46 g/day for a reference woman. The acceptable range is 10 to 35 percent of daily calories. Athletes and strength trainers commonly target 1.2 to 2.0 g/kg. The table shows the RDA in grams per day by life stage for reference body weights.
Recommended intake across life
in grams/dayBars scale to the highest recommendation shown. Where men and women differ, both values are listed.
Full reference table
| Life stage | Male | Female |
|---|---|---|
| Children 1-3 | 13 | 13 |
| Children 4-8 | 19 | 19 |
| Children 9-13 | 34 | 34 |
| Teens 14-18 | 52 | 46 |
| Adults 19+ | 56 | 46 |
| Pregnancy | n/a | 71 |
| Lactation | n/a | 71 |
Values in grams/day. AI marks an Adequate Intake, used when there is not enough evidence for a formal recommendation.
What moves the number
What changes your needs
Body weight
Needs scale with weight, about 0.8 g/kg as the baseline RDA for adults.
Activity level
Athletes and strength trainers often target 1.2 to 2.0 g/kg to support recovery and muscle growth.
Age
Older adults may benefit from 1.0 to 1.2 g/kg to help preserve muscle mass.
Pregnancy and lactation
Requirements rise to about 71 g/day to support fetal growth and milk production.
Running low
Signs you might not get enough
Most at risk: Rare in the United States but seen in older adults with poor appetite, people with eating disorders or malabsorption, and those following very restrictive diets.
Too much
Can you get too much?
For healthy people, high protein intake is generally well tolerated. Very high intakes displace other nutrients and provide no added benefit beyond the body's ability to use the amino acids.
Where to get it
Best food sources
The bottom line
Aim for at least 0.8 g/kg of body weight daily, and more if you are active, older, or recovering. Spread protein across meals and favor lean and plant sources.
Track protein automatically
Protein is one of the 92 nutrients Vora reads from a photo of your meal, so you can see where you stand without weighing or logging by hand.
Sources and method
The recommended intakes, upper limits, and food-source amounts on this page come from the primary references below. Numbers were checked against the current NIH Office of Dietary Supplements fact sheets and the Institute of Medicine (now the National Academies) Dietary Reference Intakes.
- Institute of Medicine, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005)
- National Institutes of Health, Office of Dietary Supplements
This page is for general education, not medical advice. Reference intakes are population averages for healthy people and do not replace guidance from your doctor or a registered dietitian, especially if you are pregnant, managing a health condition, or considering supplements.