Calculate how many grams of protein you need per day based on body weight, activity level, and fitness goals. ISSN-backed recommendations.
Protein is the most critical macronutrient for building and maintaining muscle, supporting immune function, and promoting satiety during weight management. This calculator provides evidence-based protein recommendations from the International Society of Sports Nutrition (ISSN), tailored to your body weight, activity level, and specific health or fitness goal.
The general guideline of 0.8 g/kg body weight (the Recommended Dietary Allowance) is the minimum to prevent deficiency in sedentary individuals — it is not optimal for athletes, active people, or anyone pursuing body composition changes. Research consistently shows that active individuals benefit from 1.6–2.2 g/kg (0.7–1.0 g/lb) for muscle building, and that higher protein intakes during calorie deficits (up to 2.3–3.1 g/kg of lean body mass) help preserve muscle during fat loss.
This calculator adjusts recommendations based on your goal — maintenance, muscle gain, weight loss, or athletic performance — and provides per-meal targets to optimize muscle protein synthesis throughout the day.
Most people underestimate their protein needs, especially during weight loss or intense training. Under-eating protein during a deficit leads to muscle loss; under-eating during a surplus limits muscle growth. This calculator translates research into a specific gram target you can use for daily planning, and distributes it across meals using the 0.4–0.55 g/kg per meal guideline from sports nutrition literature.
Daily Protein = Body Weight × Protein Factor Protein factors (g per kg body weight): • Sedentary maintenance: 0.8–1.0 • Active maintenance: 1.2–1.4 • Muscle building: 1.6–2.2 • Fat loss (calorie deficit): 1.8–2.7 • Endurance athletes: 1.2–1.6 Per-meal target: 0.4–0.55 g/kg across 3–5 meals Sources: ISSN Position Stand on Protein (2017), Schoenfeld & Aragon (2018)
Result: 144–176g protein/day
At 80 kg with a muscle-building goal, the ISSN recommends 1.6–2.2 g/kg: 80 × 1.6 = 128g (minimum) to 80 × 2.2 = 176g (maximum). A practical midpoint target is ~155g/day. Spread across 4 meals, that is ~39g per meal — roughly equivalent to 5 oz of chicken breast or 1.5 scoops of whey protein per meal.
The ISSN's 2017 position stand on protein represents the most comprehensive evidence-based review of protein needs for active individuals. The key finding is that protein intakes of 1.4–2.0 g/kg/day are sufficient for most exercising individuals, with higher amounts (up to 3.0 g/kg) posing no health risks and potentially offering small additional benefits during intensive training or calorie restriction.
A 2018 meta-analysis by Schoenfeld and Aragon found that distributing daily protein across at least 3 meals (with 0.4–0.55 g/kg per meal) maximizes the anabolic response compared to consuming the same total in 1–2 meals. The key trigger is leucine: approximately 2.5–3.0g of leucine per meal (found in about 25–40g of high-quality protein) is needed to maximally stimulate muscle protein synthesis.
During caloric restriction, protein requirements increase — this is counterintuitive but well-established. A 2014 study by Helms et al. recommended 2.3–3.1 g/kg of fat-free mass for lean, resistance-trained athletes during energy restriction. For less lean individuals, 1.8–2.4 g/kg of total body weight is a practical guideline. Prioritizing protein during dieting is the single most effective nutritional strategy for preserving muscle.
Reaching a high daily protein target is easier with a structured meal plan. A practical framework: 30–40g protein per meal across 4 meals, with optional high-protein snacks. Example protein sources per ~30g serving: 4 oz chicken breast, 5 oz salmon, 1 cup Greek yogurt + 1 scoop protein, 4 eggs, 1 scoop whey protein. Combining whole foods with occasional supplements makes hitting high targets manageable.
It depends on your goal and activity level. Sedentary adults need about 0.8–1.0 g/kg. Active individuals aiming for muscle growth need 1.6–2.2 g/kg. Those in a calorie deficit need 1.8–2.7 g/kg to preserve muscle. For a 175 lb person, this ranges from roughly 65g (sedentary) to 175g (muscle building) per day.
For healthy individuals, protein intakes up to 3.0+ g/kg have been studied without adverse effects on kidney function, bone health, or liver function. The concern about high protein damaging kidneys applies to people with pre-existing kidney disease, not healthy individuals. That said, extremely high protein diets leave less room for carbs and fats, which can impact overall nutrition.
The anabolic window is wider than once thought — distributing protein evenly across meals matters more than consuming it immediately post-workout. Research suggests 0.4–0.55 g/kg per meal across 3–5 meals optimizes muscle protein synthesis throughout the day. Post-workout protein within 2 hours is beneficial but not critical.
Complete proteins containing all essential amino acids, especially leucine (the primary trigger for muscle protein synthesis), are ideal. Top sources: whey protein, eggs, chicken breast, fish, Greek yogurt, lean beef. Plant sources like soy, pea protein, and quinoa are good alternatives but may require slightly higher amounts.
Yes. During a calorie deficit, your body is more likely to break down muscle for energy. Higher protein intake (1.8–2.7 g/kg, or up to 3.1 g/kg of lean body mass) helps preserve muscle mass and maintains metabolic rate. This is one of the most evidence-based strategies for improving body composition during weight loss.
Either works. Using total body weight with standard factors (1.6–2.2 g/kg) is simpler. Using lean body mass with higher factors (2.3–3.1 g/kg LBM) gives a more precise estimate for individuals with higher body fat. Both approaches usually converge on similar gram totals for most people.
Yes, but it requires more attention. Plant proteins are generally lower in leucine and may have incomplete amino acid profiles. Combining sources (rice + pea protein, legumes + grains) compensates for this. Aiming 10–20% higher than animal-based protein recommendations helps ensure adequate essential amino acid intake.
Older adults experience "anabolic resistance" — their muscles require more protein to stimulate the same level of muscle protein synthesis as younger adults. The ESPEN (European Society for Clinical Nutrition) recommends 1.0–1.2 g/kg for healthy older adults and 1.2–1.5 g/kg for those who are exercising or recovering from illness.