Protein requirements are not a fixed number. They scale with your body weight, activity level, age, and goals. Here's exactly what the evidence shows — with tables, formulas, and practical takeaways.
The RDA vs. Optimal Intake
The official Recommended Dietary Allowance (RDA) for protein is 0.8g per kilogram of body weight. But this is a minimum to prevent deficiency — not an amount optimized for health, performance, or body composition. For active individuals, research consistently shows higher intakes are needed and beneficial.
💡 Key Point: Think of the RDA (0.8g/kg) as the floor, not the ceiling. Most exercising adults should aim for 1.2–2.2g/kg depending on training intensity and goals.
Protein Needs by Activity Level
| Activity Level | Protein (g/kg/day) | Example: 75kg Person |
|---|---|---|
| Sedentary | 0.8g/kg | 60g/day |
| Lightly Active | 1.0–1.3g/kg | 75–98g/day |
| Moderately Active | 1.3–1.6g/kg | 98–120g/day |
| Very Active | 1.6–2.0g/kg | 120–150g/day |
| Athlete | 1.8–2.2g/kg | 135–165g/day |
How BMR and TDEE Relate to Protein
Your Basal Metabolic Rate (BMR) — the calories you burn at rest — is the foundation for calculating total energy needs. When multiplied by an activity factor, it becomes your TDEE (Total Daily Energy Expenditure). Your protein needs scale with your TDEE because more active individuals have higher muscle turnover and greater amino acid demands.
Our protein calculator uses the Mifflin-St Jeor BMR formula and applies activity-adjusted multipliers to give you an integrated calorie + protein recommendation — not just a flat g/kg number.
Protein Needs by Age
- Under 18: 0.85–1.0g/kg — growth adds protein demands
- 18–50: 1.0–2.2g/kg depending on activity
- 50–65: 1.2–1.6g/kg even if sedentary — anabolic resistance increases
- 65+: 1.4–1.8g/kg — sarcopenia prevention requires more protein per unit of body weight
Protein Needs by Gender
On a per-kilogram basis, men and women have very similar protein requirements. The main differences stem from average body weight and lean muscle mass. Women's protein needs in pregnancy increase by ~25g/day, and during breastfeeding by ~20g/day. Our calculator accounts for gender via the Mifflin-St Jeor sex adjustment in BMR.
Common Protein Myths
- Myth: "You can only absorb 30g per meal." Your body can absorb all protein — but MPS peaks at 20–40g per meal. Spreading protein is smart, but not because of absorption limits.
- Myth: "High protein damages kidneys." Only for people with existing kidney disease. In healthy adults, even 2.5–3.0g/kg is well-tolerated long-term.
- Myth: "Plant protein doesn't build muscle." Plant proteins can fully support muscle growth when combined to cover all essential amino acids. Soy is particularly close to whey in effectiveness.
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