How Much Protein Do You Actually Need Per Day?

Why the old RDA is wrong for most people

The Recommended Dietary Allowance (RDA) for protein is 0.8 g per kg of bodyweight per day. That figure comes from nitrogen-balance studies in sedentary adults and represents the minimum intake needed to prevent deficiency in 97.5% of the healthy population. It is a floor — not a target. It was never designed to optimise body composition, support training, or preserve muscle during weight loss.

A generation of research has since shown that higher intakes produce better outcomes for anyone who trains, anyone in a calorie deficit, and most adults over 50. The 2018 meta-analysis by Morton et al. — covering 49 studies and over 1,800 participants — found that protein intakes up to 1.6 g/kg/day progressively increased lean mass gains. Intakes beyond that showed diminishing returns in the general population, though elite athletes and dieters may benefit from 2.0 to 2.4 g/kg.

So the real question is not "how little can I get away with" but "what does my situation actually call for".

The target, by goal

• Sedentary, not dieting: 1.0 to 1.2 g/kg. Above the RDA, which plenty of research suggests is low even for non-exercisers.
• General fitness, regular training: 1.4 to 1.8 g/kg. The sweet spot for most recreationally active adults.
• Building muscle: 1.6 to 2.2 g/kg. Higher end for advanced lifters in a surplus.
• Cutting fat while training: 2.0 to 2.4 g/kg. The muscle-preserving dose during a calorie deficit.
• Older adults (65+): 1.2 to 1.6 g/kg minimum, 2.0 g/kg if training. Anabolic resistance makes older tissue less responsive to protein, so the dose needs to go up.
• Endurance athletes: 1.4 to 1.8 g/kg. Still higher than the RDA; endurance training increases protein turnover.

For a 70 kg recreational lifter doing a fat-loss phase, the target is 140 to 170 g/day. For a 90 kg man in a muscle-building phase, 145 to 200 g/day. For a 55 kg woman maintaining weight and training, 85 to 100 g/day.

Why protein matters so much in a deficit

A calorie deficit is a stress signal. Your body responds by burning fat, burning muscle, or both. The macro composition of your diet is one of the largest levers on which way that ratio tilts. The research here is consistent:

• High protein protects lean mass. Across dozens of studies, dieters eating 2.0+ g/kg retain substantially more muscle than those at 0.8 to 1.2 g/kg, at the same calorie deficit.
• Protein is the most satiating macro. Gram for gram, it reduces hunger more than fat or carbs — useful when you are in a deficit by definition.
• Protein has the highest thermic effect. Digesting and processing protein costs 20 to 30% of its calories, versus 5 to 10% for carbs and 0 to 3% for fat. A 150 g/day protein intake eats about 100 kcal of its own energy in digestion.

The upshot: raising protein while cutting calories is one of the highest-leverage changes you can make. You keep muscle, you feel fuller, and you burn more calories digesting it.

Distribution: timing matters (a bit)

Muscle protein synthesis (MPS) is stimulated by a meal that delivers roughly 0.3 to 0.4 g/kg of protein — about 20 to 40 g for most people. After that, MPS plateaus until the next meal. Studies by Areta and colleagues have shown that distributing protein across 4 meals produces higher 12-hour MPS than the same total in 2 meals or 8 meals.

Practical translation: aim for 3 to 5 protein meals a day, each containing 25 to 45 g. Most people already do this at lunch and dinner and then fail at breakfast (a bowl of cereal with milk has maybe 12 g) and snacks (a banana and a handful of almonds is 6 g). Those two windows are where intake typically falls apart.

What 30 g of protein actually looks like

• 100 g cooked chicken breast, salmon, or lean beef
• 170 g Greek yogurt (plain, 0%) + a scoop of whey
• 1 cup cottage cheese
• 1 can of tuna (~ 140 g drained)
• 175 g firm tofu
• 100 g tempeh
• 1 scoop whey or pea protein isolate
• 5 large eggs (also ~30 g fat, so this is a higher-calorie route)

Note the variety of calorie levels. 100 g of chicken breast is roughly 165 kcal for 31 g of protein; 5 eggs is 360 kcal for 30 g of protein. Same macronutrient, very different efficiency.

Common mistakes

• Protein bars as a strategy. Many "protein" bars are 10 to 15 g of protein in 200 to 250 kcal. They are snacks, not protein sources. Read labels.
• Counting collagen or gelatin as complete protein. They are low in leucine and incomplete. Fine as a small contribution; not a main source.
• Obsessing over grams at the expense of training. Protein above 1.6 g/kg is a small optimisation. Training consistency is a large one. Get training right first.
• Underestimating how little protein is in most meals. A typical Western dinner without a deliberate protein centrepiece is 15 to 25 g. You need three or four of those a day to hit targets, and very few people do.

A simple weekly rollout

If you are currently at 0.8 to 1.0 g/kg and want to get to 1.8 g/kg, do not try to double overnight. Digestion adjusts. Add 20 to 30 g per week: an extra scoop of whey, a bigger breakfast portion, a second protein source at lunch. Track for a week at each level. Within 3 to 4 weeks you will be eating the target intake without it feeling like effort.