Protein Intake Calculator

Protein requirements depend on body weight, activity level and training goals. The UK Reference Nutrient Intake (RNI) is 0.75 g per kilogram of body weight per day for sedentary adults. Active individuals and those doing strength training typically need 1.2–2.0 g/kg to support muscle repair and growth.

This calculator takes your weight, activity level and goal to produce a personalised daily protein target in grams. It also shows how to distribute protein across meals, since research suggests spreading intake evenly (20–40 g per meal) maximises muscle protein synthesis.

Good UK protein sources include chicken breast (~31 g per 100 g), tinned tuna (~25 g), eggs (~6 g each), Greek yoghurt (~10 g per 100 g) and lentils (~9 g per 100 g cooked). Meeting higher targets often requires planning meals around a protein source first.

UK Reference Nutrient Intake (RNI) for protein. Adults: 0.75g per kg body weight daily — minimum to prevent deficiency. 70kg adult: 52g/day RNI. UK average actual intake: 75-90g/day (above RNI). Recommended for active people: 1.2-1.6g/kg = 84-112g for 70kg. For muscle building: 1.6-2.2g/kg = 112-154g. Elderly: 1.0-1.2g/kg recommended (prevents sarcopenia — age-related muscle loss). Pregnancy: +6g/day from RNI; breastfeeding: +11g.

Best UK protein sources. Per 100g cooked: chicken breast 31g; turkey 29g; tuna canned 28g; salmon 25g; beef mince 26g; eggs 13g (single egg 6g); Greek yogurt 10g; cottage cheese 12g; lentils 9g (cooked); chickpeas 9g; tofu 8g; quinoa 4.4g; nuts 20-25g; whey protein 20-25g/scoop. Vegan sources: tempeh, tofu, lentils, chickpeas, hemp seeds. UK food cost per 50g protein: chicken breast £0.80; eggs £1.00; lentils £0.35 (cheapest); whey protein £0.50.

Protein quality — biological value. Animal proteins: complete (all 9 essential amino acids). Plant proteins: often missing 1+ amino acids — combine grains + legumes for complete profile (e.g. beans + rice; hummus + pita; peanut butter on whole wheat). DIAAS (Digestible Indigestible Amino Acid Score) — modern protein quality measure. Top scores: whey (1.18), egg white (1.16), milk (1.14), beef (1.11), soy (1.00). Lower: wheat (0.40), rice (0.59) — fine if mixed with legumes.

Timing — does it matter? Total daily protein matters more than timing for most. BUT: muscle protein synthesis peaks 24-48 hours after exercise. Distribute protein evenly across 3-4 meals (25-40g per meal) — better than 1 large meal. Pre/post workout: 20-40g protein within 2-hour window optimal but not essential. Leucine (3g per meal): triggers muscle protein synthesis — explains why whey protein (high leucine) often beats plant proteins for muscle building. Sleep snack: casein protein (cottage cheese, Greek yogurt) provides slow overnight protein release.

Protein and weight loss. High-protein diet (25-35% of calories) during weight loss: preserves muscle, increases satiety, thermic effect of food (25-30% of protein calories used in digestion vs 5-10% carbs/fat). 70kg person losing weight: 112-154g protein/day prevents muscle loss. Without enough protein: 30-50% of weight lost can be muscle = worst outcome ('skinny fat'). Cheap protein for budget weight loss: eggs, canned tuna, lentils, Greek yogurt, whey protein powder. NHS guideline: 2 portions fish/week including 1 oily fish.