How much protein do you need by age and weight?: A personalized nutrition guide

October 22, 2025 •

4 min read

The Recommended Dietary Allowance (RDA) for a healthy, sedentary adult is a baseline 0.8 grams of protein per kilogram of body weight, but your actual needs can vary dramatically throughout your life. This guide explores how much protein do you need by age and weight?, tailoring advice for different life stages and goals.

Quick Summary

Protein requirements vary significantly based on factors like age, weight, and activity level. Optimal intake supports muscle maintenance, growth, and overall health throughout life, from childhood to old age.

Key Points

RDA is a minimum: For sedentary adults, the RDA of 0.8 g/kg body weight prevents deficiency but is not optimal for muscle growth or preservation.
Age increases needs: Older adults require more protein (1.2-1.5 g/kg) to combat age-related muscle loss (sarcopenia).
Activity boosts demand: Athletes and very active individuals need higher protein intake (1.2-2.2 g/kg) to support muscle repair and growth.
Weight loss requires more protein: Higher protein intake (1.6-2.4 g/kg) during a calorie deficit helps preserve muscle mass and increases satiety.
Timing and quality matter: Spreading high-quality protein intake evenly throughout the day, rather than in one large meal, is more effective for muscle protein synthesis.
Listen to your body: Signs of inadequate intake include fatigue, weakened immunity, and slow healing, while excessive intake can strain kidneys, especially in those with pre-existing issues.

Why protein matters for your body

Protein is a crucial macronutrient composed of amino acids, the building blocks for every cell, tissue, and organ in your body. It is essential for numerous physiological functions, including:

Building and repairing muscle tissue
Creating enzymes and hormones
Supporting immune function
Maintaining healthy hair, skin, and nails
Contributing to bone health

While protein is vital, there is no one-size-fits-all recommendation for daily intake. Your specific needs depend on several factors, including your age, weight, gender, and level of physical activity. The following sections break down protein requirements across different life stages and scenarios.

Protein needs during childhood and adolescence

During periods of rapid growth and development, children and teenagers require adequate protein to build and repair body tissue. Their needs, calculated based on body weight, are proportionally higher than those of sedentary adults.

Infants (0-6 months): Require approximately 1.43 g/kg of body weight.
Infants (7-12 months): Need about 1.60 g/kg of body weight.
Children (1-3 years): The RDA is approximately 1.08 g/kg of body weight.
Children (4-8 years): The RDA is around 0.91 g/kg of body weight.
Teenagers (9-13 years): The RDA is approximately 0.94 g/kg for boys and 0.87 g/kg for girls.
Teenagers (14-18 years): Needs diverge based on sex, with boys requiring about 0.99 g/kg and girls needing 0.77 g/kg, reflecting differences in muscle mass and growth.

Protein needs for sedentary adults

For an average, healthy adult who gets minimal physical activity, the RDA is 0.8 grams of protein per kilogram of body weight. This baseline is the minimum required to prevent deficiency, but it is not optimized for performance or muscle maintenance. To calculate your minimum intake, you can multiply your weight in kilograms by 0.8. For example, a sedentary 70 kg (154 lb) person would need around 56 grams of protein per day.

Enhanced protein for athletes and active individuals

For those who engage in regular physical activity, protein requirements increase significantly to support muscle repair and growth. Protein intake for athletes varies depending on the intensity and type of exercise.

Endurance athletes: May require 1.2 to 2.0 g/kg per day to repair muscle fibers and support energy needs.
Strength/Power athletes: Need between 1.6 and 2.2 g/kg per day to maximize muscle protein synthesis and promote muscle growth.
Active individuals: Those who exercise moderately may need slightly more than sedentary adults, in the range of 1.0 to 1.2 g/kg.

Optimizing protein intake for weight loss

When aiming for weight loss, a higher protein intake is often recommended, especially during a caloric deficit. Protein helps preserve lean muscle mass while promoting satiety, which can help control appetite and prevent overeating. Recommendations for fat loss and muscle preservation typically fall in the range of 1.6 to 2.4 g/kg of body weight.

Increased protein needs for older adults

After the age of 50, a natural decline in muscle mass, known as sarcopenia, begins. To counteract this and maintain muscle function, older adults need more protein than younger adults.

Over 65 years: Aim for 1.2 to 1.5 g/kg of body weight per day. This can help preserve muscle mass, strength, and mobility.

Special considerations: Pregnancy and lactation

During pregnancy and lactation, a woman's body requires extra protein to support fetal development and milk production.

Pregnancy: Needs increase to approximately 1.1 g/kg per day.
Lactation: Protein requirements are elevated further to produce nutritious breast milk. Studies using the indicator amino acid oxidation (IAAO) technique suggest requirements could be around 1.7–1.9 g/kg per day, significantly higher than previous estimates.

Protein requirements for various populations


Population Group	General Recommendation (g/kg/day)	Considerations
Sedentary Adults	0.8	Minimum intake for general health; may not be optimal for muscle preservation.
Infants (0-12 months)	1.43 - 1.60	Crucial for rapid growth and development.
Older Adults (>65 years)	1.2 - 1.5	Helps combat age-related muscle loss (sarcopenia).
Endurance Athletes	1.2 - 2.0	Supports muscle repair and recovery from prolonged exercise.
Strength Athletes	1.6 - 2.2	Maximizes muscle protein synthesis and growth.
Weight Loss (Caloric Deficit)	1.6 - 2.4	Preserves muscle mass and increases satiety.
Pregnant Women	1.1	Supports fetal development and increased physiological needs.
Lactating Women	Up to 1.9	Significantly higher needs to support milk production.

The importance of protein quality and timing

Beyond the total daily amount, the type and timing of your protein intake can also impact its effectiveness. Animal proteins like meat, eggs, and dairy are considered 'complete' proteins, containing all nine essential amino acids. Many plant-based proteins are 'incomplete' but can be combined throughout the day to provide a full amino acid profile. Spreading protein intake evenly across meals can optimize muscle protein synthesis, especially for athletes and older adults. Aiming for 20-30 grams of high-quality protein per meal is a good strategy for maximizing benefits.

Conclusion: Finding your personalized protein goal

Instead of aiming for a universal protein target, the key is to determine your personalized intake based on your unique circumstances. Consider your age, body weight, activity level, and health goals. For most healthy adults, a range of 0.8 to 1.6 grams per kilogram of body weight is a good starting point, but athletes, older adults, and those on a weight loss journey may benefit from the higher end of that spectrum. Tracking your intake and adjusting based on your results is the most effective strategy. Always consult a healthcare provider or a registered dietitian if you have underlying health conditions, such as kidney disease, as excessive protein can be harmful. A balanced diet with high-quality protein, combined with regular exercise, is the best path to supporting muscle mass and overall well-being throughout your life.

For more detailed information, consult the resource on protein from The Nutrition Source at Harvard T.H. Chan School of Public Health.

Frequently Asked Questions

To calculate your protein needs, convert your weight from pounds to kilograms by dividing by 2.2. Then, multiply your weight in kilograms by the appropriate factor for your age, activity level, or goal. For a sedentary adult, multiply by 0.8, while an active individual may use a factor of 1.2 to 2.0.

Signs of inadequate protein intake can include muscle weakness and fatigue, brittle hair and nails, frequent sickness due to a weakened immune system, swelling (edema), and slow healing of injuries.

For healthy individuals, consuming a higher amount of protein (up to 2.0 g/kg) is generally safe, but consistently eating excessive amounts can place extra strain on the kidneys. It may also lead to digestive issues or displace other essential nutrients in your diet. Consult a doctor if you have concerns about kidney health.

Animal proteins are 'complete,' meaning they contain all essential amino acids. Many plant proteins are 'incomplete' on their own but can be combined throughout the day to provide a complete profile. Newer research suggests that when consumed in sufficient amounts, plant proteins can be just as effective for muscle health.

Spreading your protein intake evenly across meals is more effective for stimulating muscle protein synthesis, particularly for active individuals and older adults. Aiming for 20-30 grams of protein per meal is a good strategy.

Yes, older adults need more protein than their younger, sedentary counterparts. Their bodies become less efficient at utilizing protein for muscle maintenance (anabolic resistance), so a higher intake of around 1.2 to 1.5 g/kg is recommended to prevent sarcopenia.

Pregnant women need increased protein to support fetal growth, with recommendations around 1.1 g/kg per day. During lactation, requirements increase further, possibly up to 1.9 g/kg, to support milk production.