How much protein per day

Four ranges, four different questions

The reason answers to this question vary so wildly is that they are answers to different questions. The Institute of Medicine set an RDA of 0.8 g per kilogram of body weight per day: the intake judged sufficient to meet the requirement of nearly all healthy adults. The 2016 joint position statement from the Academy of Nutrition and Dietetics, Dietitians of Canada and ACSM puts athlete intakes generally at 1.2 to 2.0 g/kg. The ISSN's 2017 position stand states 1.4 to 2.0 g/kg is sufficient for most exercising individuals to build and maintain muscle. PROT-AGE recommends at least 1.0 to 1.2 g/kg for healthy people over 65. Each is cited on its own terms here; blending them into one number would destroy the only information they carry.

Why the RDA is a floor and not a target

An RDA is defined as the intake that meets the requirement of nearly all healthy people in a group - it is set above the EAR, the median requirement, precisely so that almost nobody falls short. That makes it a threshold for adequacy, not a description of an optimum, and the IOM did not present it as one. The same 2005 report also publishes the AMDR, which allows protein anywhere from 10 to 35 percent of total energy. At 2,500 kcal a day, 35 percent is 219 g. The RDA and the top of the AMDR come from the same document and are nearly four times apart, because they are answering different questions.

Per meal, and how far apart the meals sit

The ISSN position stand goes further than a daily total. It puts a per-meal dose at 0.25 g per kilogram of body weight, or an absolute 20 to 40 g, and states that doses are ideally distributed evenly every three to four hours. For an 80 kg body that is 20 g per meal by the per-kilogram route, which sits at the bottom of the absolute range - a reminder that the two rules the same paper gives do not always land in the same place, and that it published a range rather than a figure for exactly that reason.

Where the ranges stop

They stop at healthy adults, and the sources say so. PROT-AGE names kidney disease explicitly as the case where intake becomes a clinical decision rather than a calculator one. The ranges are also written against body weight as measured, so entering a goal weight returns the target for a different body - a legitimate thing to look at, as long as you know that is what you are looking at. Nothing on this page is a reason to change what you eat; it is a statement of what four named organisations published, in grams, for a body of your weight.

Official sources

• Institute of Medicine, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005)
• Academy of Nutrition and Dietetics, Dietitians of Canada and ACSM, Nutrition and Athletic Performance joint position statement (2016)
• Jager et al., International Society of Sports Nutrition position stand: protein and exercise, J Int Soc Sports Nutr 2017
• Bauer et al., PROT-AGE Study Group position paper, J Am Med Dir Assoc 2013

Frequently asked questions