Protein Intake Statistics: Daily Requirements & Effects

The Recommended Dietary Allowance for protein is 46 g a day for adult women and 56 g a day for adult men, within a range of 10-35% of calories

Institute of Medicine values reproduced in the Dietary Guidelines' nutritional goals; pregnancy and breastfeeding raise the RDA to 71 g a day.

Up to 46% of US adults aged 71 and over did not meet the protein recommendation of 0.8 g per kg of body weight a day

NHANES 2005-2014, 11,680 adults aged 51 and over. Those below the recommendation had poorer diet quality and more functional limitations, and lower grip strength over 70.

Protein supplementation during resistance training added 2.49 kg to 1RM strength and 0.30 kg to fat-free mass on average

Meta-analysis of 49 randomized trials with 1,863 participants, training for at least 6 weeks.

Gains in fat-free mass stopped rising once total protein intake passed about 1.62 g per kg of body weight a day

Break-point analysis in the same meta-analysis. Supplementation helped less with age and more in resistance-trained people (+0.75 kg).

Lean, resistance-trained athletes in a calorie deficit likely need 2.3-3.1 g of protein per kg of fat-free mass a day

Systematic review of six studies; needs scale up with the size of the deficit and leanness. Per kg of fat-free mass, not body weight.

To maximize muscle building, a target of 0.4 g of protein per kg per meal across at least four meals reaches at least 1.6 g/kg a day; spreading 2.2 g/kg over four meals needs up to 0.55 g/kg per meal

Review. Doses above about 20-25 g raise amino-acid oxidation, but not all the extra protein is wasted: some still goes to building tissue.

Protein intakes of 1.3-1.8 g per kg a day, eaten as 3-4 evenly sized meals, maximize muscle protein synthesis in athletes; 1.8-2.0 g/kg may help preserve lean mass in a deficit

Consensus review; experienced athletes may need less and periods of high-frequency or high-intensity training more.

Adults over 65 should average at least 1.0-1.2 g of protein per kg a day, at least 1.2 g if active, and 1.2-1.5 g with acute or chronic disease

Position paper of the PROT-AGE Study Group. People with severe kidney disease not on dialysis are the exception and may need to limit protein.

After resistance exercise, muscle protein synthesis was about 122% higher with whey than with casein and 31% higher than with soy

18 young men (6 per group), each drink matched for 10 g of essential amino acids. At rest, whey beat casein by about 93%.

A vegan high-protein diet built as much muscle as an omnivorous one over 10 weeks of training: lean mass +3.1 kg versus +2.6 kg

22 young adults eating about 2 g/kg a day, much of the vegan protein from mycoprotein. Thigh muscle volume rose 8.3% in both groups.

Raising protein from 15% to 30% of calories cut spontaneous intake by 441 kcal a day and body weight by 4.9 kg over 12 weeks

19 participants with carbohydrate held at 50% of calories; fat mass fell 3.7 kg.

Protein typically supplies only about 15% of dietary energy and has stayed nearly constant through the obesity epidemic; Simpson and Raubenheimer argue that this lets the appetite for protein drive overeating

A hypothesis formalized as a mathematical model, with supporting but not conclusive evidence: people may overeat total energy on low-protein diets until protein needs are met.

Digesting a mixed diet costs 5-15% of daily energy expenditure, more with higher protein intakes

Review of diet-induced thermogenesis; protein-induced thermogenesis also contributes to satiety.

40 g of casein 30 minutes before sleep raised overnight muscle protein synthesis by about 22% after evening resistance exercise

16 young men; the muscle result was borderline significant (P = 0.05), while whole-body protein synthesis and balance improved clearly.

Joint sports-nutrition guidance holds that performance and recovery are enhanced by well-chosen nutrition and recommends referral to a registered dietitian for a personal plan

Position of the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine.