How Much Protein Do Adults Need? Three Different Answers

The baseline: 0.8 grams per kilogram

The figure behind most protein advice in the United States is the Recommended Dietary Allowance of 0.8 grams of protein per kilogram of body weight per day for adults, set by the Institute of Medicine in its 2005 Dietary Reference Intakes for macronutrients. For someone weighing 70 kilograms (about 154 pounds), that works out to 56 grams a day.

The way that number is defined matters for reading it correctly. A Recommended Dietary Allowance is set to cover the needs of nearly all healthy people in a group, which means it sits above the average requirement by design. It is a threshold for avoiding deficiency in a healthy adult, and it was never intended to describe the intake at which muscle, strength or recovery is maximized.

Recommended Dietary Allowance (RDA)

The average daily intake that is sufficient to meet the nutrient requirement of nearly all (97 to 98 percent) healthy individuals in a particular life stage and sex group.

The same Institute of Medicine report also set an Acceptable Macronutrient Distribution Range for protein of 10 to 35 percent of total calories. This range describes the share of an eating pattern, not a requirement. Someone eating 2,000 calories a day at 10 percent protein would take in about 50 grams, while someone at 35 percent would take in about 175 grams. The width of the band reflects that no single point is known to be correct for everyone.

How the per-kilogram calculation works

Protein targets are expressed per kilogram of body weight because needs scale with body size, particularly with lean tissue. The arithmetic is simple: convert your weight to kilograms by dividing pounds by 2.2, then multiply by the grams per kilogram that apply.

The weight used in the calculation raises a genuine question for people with a high body weight, since lean mass rather than total mass drives protein requirements. Guidelines are written for body weight in the typical range, and for people well outside it a clinician or registered dietitian can say whether to use current weight, a healthy-weight reference, or something else.

Why older adults are given a higher range

The PROT-AGE Study Group, an international group of researchers in geriatrics and nutrition, published a position paper in 2013 on protein intake in older people. It concluded that healthy adults aged 65 and over should consume an average of 1.0 to 1.2 grams per kilogram of body weight per day, and more for those who are physically active or who have acute or chronic illness, with exceptions for severe kidney disease.

The reasoning is that older muscle responds less efficiently to a given amount of protein, a phenomenon sometimes called anabolic resistance, and that loss of muscle and strength with age carries real consequences for mobility and independence. A higher intake is one input to counter that, alongside resistance exercise, which the same literature treats as at least as important.

People who train regularly

The joint position statement of the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine on nutrition and athletic performance recommends a protein intake of 1.2 to 2.0 grams per kilogram of body weight per day for athletes, depending on the type and intensity of training and on total energy intake.

Two details of that statement are easy to miss when it is shortened to a headline. First, the range is wide for a reason: endurance and strength training have different demands, and someone in an energy deficit may need more to preserve lean mass. Second, the statement emphasizes that total energy intake matters and that spreading protein across meals, rather than concentrating it in one, is a reasonable approach.

Training a few times a week at a recreational level does not automatically place someone at the top of that range. Most people who exercise moderately are comfortably covered by the lower end, and many already eat above it without trying.