Nutrition Diet: How Much Protein by Age and Weight?

October 9, 2025 •

4 min read

For the average sedentary adult, the Recommended Dietary Allowance (RDA) for protein is 0.8 grams per kilogram of body weight. However, this is just the baseline, and your specific protein needs vary significantly based on individual factors, making it crucial to understand exactly how much protein by age and weight you should be consuming.

Quick Summary

An individual's daily protein requirements are influenced by their age, body weight, and activity level. This guide details how to calculate your personal protein needs and provides recommendations for different life stages and physical activity intensities.

Key Points

RDA is a Minimum: The standard RDA of 0.8 grams per kilogram of body weight is the minimum to prevent deficiency, not necessarily the optimal amount for everyone.
Age Increases Need: Older adults often require more protein (1.0–1.2 g/kg) to combat age-related muscle loss (sarcopenia).
Activity Increases Need: Athletes and those with higher physical activity levels require more protein (up to 2.0 g/kg) to support muscle repair and growth.
Special Conditions: Pregnant and lactating individuals need increased protein to support fetal development and milk production.
Avoid Extremes: Consuming too little protein can cause muscle wasting, while consistently excessive intake can lead to kidney strain, dehydration, and nutrient imbalances.
Variety is Key: Eating a variety of protein sources, both animal and plant-based, ensures a broad spectrum of essential amino acids and nutrients.

The Foundational Role of Protein

Protein is a crucial macronutrient composed of amino acids, which are the building blocks for nearly every cell and tissue in your body. It is essential for muscle repair, immune function, hormone production, and overall cellular activity. Without adequate protein, the body cannot function optimally, leading to a range of potential health issues. However, needs are not static; they fluctuate throughout your life based on development, aging, and lifestyle.

Calculating Your Baseline Protein Needs

The most common starting point for estimating protein intake is based on body weight. While the RDA provides a minimum to prevent deficiency, many people, especially those who are active or older, may benefit from a higher intake.

To calculate the basic RDA:

In kilograms: Multiply your body weight in kilograms by 0.8. For example, a 70 kg person would need about 56 grams of protein (70 * 0.8 = 56).
In pounds: Multiply your body weight in pounds by 0.36. For example, a 150-pound person would need about 54 grams of protein (150 * 0.36 = 54).

This calculation provides the minimum to sustain basic function. It's not the target for everyone, but a useful starting point.

Protein Requirements by Life Stage and Activity

Children and Adolescents

During childhood and adolescence, the body is undergoing rapid growth and development, requiring a higher protein intake per kilogram of body weight than in sedentary adults. These needs change as children age. For example:

Ages 1-3: Approximately 1.08 g/kg of body weight.
Ages 4-8: Approximately 0.91 g/kg of body weight.
Ages 9-13 (Boys): Approximately 0.94 g/kg of body weight.
Ages 14-18 (Boys): Approximately 0.99 g/kg of body weight.
Ages 14-18 (Girls): Approximately 0.77 g/kg of body weight.

Adults (19-65 years)

For most healthy, sedentary adults, the 0.8 g/kg RDA is sufficient to prevent deficiency. However, active individuals have higher needs to support muscle repair and growth. The recommendations for different activity levels are as follows:

Low to Minimal Activity: 0.8–1.0 g/kg of body weight.
Moderate Intensity Exercise: 1.2–1.5 g/kg of body weight.
Intense Training/Strength Athletes: 1.6–2.0 g/kg of body weight.

Older Adults (65+ years)

As we age, a condition known as sarcopenia, or age-related muscle loss, begins to occur. To counteract this and maintain muscle mass, older adults are often advised to consume more protein than younger, sedentary adults. The International PROT-AGE Study Group recommends that healthy older adults aim for an intake of 1.0 to 1.2 g of protein per kg of body weight. For those with acute or chronic diseases, requirements may increase further to 1.2–1.5 g/kg.

Pregnancy and Lactation

Protein needs also increase significantly during pregnancy and breastfeeding to support the growth and development of the fetus and milk production. The additional protein requirements vary throughout these periods, with general recommendations placing the total intake around 1.0–1.1 g/kg.

Potential Risks: Too Much or Too Little Protein

Getting the right amount of protein is a balancing act. Both excessive and insufficient intake can lead to health problems.

Risks of Inadequate Protein Intake

Muscle wasting: The body breaks down muscle tissue for amino acids.
Impaired immune function: Increased susceptibility to infections.
Edema: Swelling due to fluid balance disruption.
Hair and skin issues: Brittle hair, thinning, and skin rashes.
Stunted growth: Especially in children.

Risks of Excessive Protein Intake

Kidney strain: In healthy individuals, kidneys adapt, but excessive intake can be problematic for those with pre-existing kidney disease.
Dehydration: Increased protein metabolism requires more water to excrete nitrogen waste.
Digestive issues: High-protein diets, especially those low in fiber, can cause constipation and bloating.
Nutrient imbalance: Focusing too much on protein can lead to a deficiency in other important nutrients, like fiber from fruits and vegetables.

Balancing Your Diet with Quality Protein Sources

Ensuring you get enough protein means choosing the right sources. A variety of both animal and plant-based foods can help you meet your daily goals.

Common Protein Sources

Lean meats (beef, pork, lamb)
Poultry (chicken, turkey)
Fish and seafood (salmon, tuna, shrimp)
Eggs
Dairy (milk, Greek yogurt, cottage cheese, cheese)
Legumes and beans (lentils, chickpeas, soybeans)
Nuts and seeds (almonds, walnuts, pumpkin seeds)
Whole grains (quinoa, wild rice)
Soy products (tofu, tempeh)

Comparing Protein Sources


Food (per 100g, cooked)	Protein (approx.)	Essential Amino Acids	Notes
Chicken Breast	~31g	Complete	Lean source, highly versatile.
Lentils	~9g	Incomplete	High in fiber, requires pairing with grains for complete profile.
Salmon	~22g	Complete	Rich in omega-3 fatty acids.
Tofu	~16g	Complete	Versatile plant-based option.
Greek Yogurt (Plain)	~10g	Complete	Good source of calcium and probiotics.
Quinoa	~4g	Complete	A whole grain and complete protein source.
Cottage Cheese (low-fat)	~12g	Complete	High in casein protein, which digests slowly.

Conclusion

Determining how much protein by age and weight you need is an essential step toward optimizing your diet for health and performance. While the standard RDA of 0.8 g/kg serves as a basic guideline, specific circumstances such as age, activity level, and special life stages necessitate a more personalized approach. By understanding your body's changing needs and incorporating a variety of high-quality protein sources, you can effectively support everything from muscle maintenance in old age to athletic performance. Always consider consulting a healthcare professional or registered dietitian for tailored advice, especially if you have existing health conditions like kidney disease.

For a general overview of recommended daily protein intake, refer to resources from reputable organizations like Harvard Health Publishing.

Frequently Asked Questions

A sedentary adult is recommended to consume a minimum of 0.8 grams of protein per kilogram of body weight per day. This can also be calculated by multiplying your weight in pounds by 0.36.

Yes, older adults are advised to consume a higher protein intake, typically 1.0 to 1.2 grams per kilogram of body weight, to help maintain muscle mass and combat sarcopenia.

Athletes and active people have higher protein requirements to support muscle repair and growth. Depending on the intensity, needs can range from 1.2 to 2.0 grams per kilogram of body weight per day.

Yes, it is possible to get enough protein from a plant-based diet by consuming a variety of plant protein sources. Pairing foods like legumes and grains helps ensure you get all essential amino acids.

Symptoms of protein deficiency include fatigue, muscle weakness, edema (swelling), brittle hair and nails, and a weakened immune system.

Excessive protein intake, particularly above 2.0 g/kg of body weight consistently, can potentially cause kidney strain, dehydration, digestive problems, and nutrient imbalances.

Easy ways to increase protein intake include adding a source of protein to every meal, choosing high-protein snacks like Greek yogurt or nuts, and opting for protein-rich options like eggs at breakfast.