Protein needs are best expressed relative to body weight rather than a single number for everyone. The Recommended Dietary Allowance established by the National Academies of Sciences, Engineering, and Medicine is 0.8 grams per kilogram of body weight per day for healthy adults, a level estimated to meet the needs of most people. This baseline is intended to prevent deficiency but does not necessarily optimize muscle maintenance, recovery from exercise, or health in older adults.
How to estimate your intake
To calculate a basic target, multiply body weight in kilograms by 0.8. For example, a 70 kilogram adult would need about 56 grams daily. Many researchers and clinicians advise higher amounts for specific goals. Stuart M. Phillips McMaster University has published research showing that older adults and people engaged in regular resistance training often benefit from 1.2 to 1.6 grams per kilogram per day to preserve or build muscle mass. For athletes and people with very high training volumes, professional organizations such as the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine recommend a range of 1.2 to 2.0 grams per kilogram per day depending on sport, intensity, and whether the goal is maintenance, hypertrophy, or weight loss combined with training.
Causes and consequences
Protein needs rise with conditions that increase protein breakdown or demand for repair: aging-related muscle loss, illness, surgery, infection, pregnancy, lactation, and intensive physical training. Insufficient intake over time can contribute to sarcopenia, impaired immune response, slower wound healing, and reduced strength and functional capacity. Conversely, very high intakes are unlikely to provide extra benefit for sedentary people and can pose risks for those with preexisting kidney disease. For people with normal kidney function, research has not shown harmful effects from moderately higher intakes within the athletic and older-adult ranges, but individual medical evaluation is prudent.
Cultural and environmental factors shape how people meet protein needs. Diets centered on animal products can provide high-quality, complete amino acid profiles but carry greater greenhouse gas emissions and land use per gram of protein in many regions. Plant-based approaches such as combining legumes, grains, nuts, and seeds can meet needs while aligning with cultural preferences and lowering environmental footprint. Food availability, culinary traditions, affordability, and territorial agricultural patterns all influence realistic and sustainable choices.
Aim for protein distribution across the day rather than concentrating intake in one meal; spreading moderate amounts with each meal supports muscle protein synthesis more effectively. Protein quality matters: animal sources and certain plant foods like soy and quinoa have more complete amino acid profiles, while varied plant combinations achieve the same outcome.
Individual needs vary by age, health status, and activity; use the RDA as a baseline, consider higher targets when warranted, and consult a qualified clinician or registered dietitian for personalized guidance.