Protein calculator

For an adult who trains and wants to keep muscle, the evidence-backed range is roughly 1.6–2.2 g per kilogram of body weight a day. This calculator uses 2.2 g/kg while losing weight — the top of that range, because a calorie deficit is exactly when lean mass is at risk — 1.8 g/kg at maintenance, and 2.0 g/kg when gaining.

Those figures are far above the 0.8 g/kg that dietary guidelines set as a minimum, and the difference confuses people. The guideline number is the amount needed to prevent deficiency in a sedentary adult; it is a floor for avoiding harm, not the amount that best supports training, satiety, or body composition.

If you are sedentary and not trying to change your weight, you need less than this calculator suggests. If you are dieting, training hard, or over about 60, the higher end earns its place.

Two adjustments separate this calculator from the usual multiplication, and both matter for real bodies.

Above a BMI of 25, protein is calculated from an adjusted body weight rather than your full weight: the weight at a BMI of 25, plus 40% of the excess. This is the standard clinical convention for prescribing protein in obesity, and the reasoning is simple — lean mass does not rise one-for-one with body fat, so a flat gram-per-kilogram figure over-prescribes protein for higher-BMI profiles without any added benefit.

The target is also capped so that at least 20% of your calories can still come from fat. Because protein is prescribed per kilogram of body weight and fat is prescribed as a share of calories, a low-calorie plan for a heavier person can otherwise leave almost nothing for dietary fat — which carries essential fatty acids and fat-soluble vitamins. When the cap engages, the calculator says so rather than quietly returning an impossible number.

Total daily protein does most of the work, but distribution helps at the margin. Roughly 25–40 g at each of three or four meals is easier to absorb into a routine than one enormous serving, and it keeps you fuller across the day rather than for one hour after dinner.

The practical obstacle is almost always breakfast, which in most eating cultures is the lowest-protein meal by a wide margin. Fixing that one meal often closes most of the gap between where people are and where they want to be.

Roughly speaking, 100 g of cooked chicken breast is about 30 g of protein; a 150 g pot of Greek yoghurt around 15 g; three eggs about 19 g; 100 g of lentils once cooked about 9 g; a scoop of whey powder 20–25 g. Hitting 150 g a day is three solid protein-centred meals plus a snack, not an exotic diet.

Plant-based eating makes the target harder but not unreachable: lean on legumes, tofu, tempeh, seitan, and dairy or a supplement if you use them, and expect to eat more total food for the same protein, since plant sources carry more carbohydrate alongside.

Past roughly 2.2 g/kg the additional benefit for muscle retention flattens out, and the calories have to come from somewhere — usually at the expense of carbohydrate, which fuels training, or fat, which you need. Very high intakes are not dangerous for healthy people, but they are not free either.

The one real caution is kidney disease. In healthy kidneys, high protein intake has not been shown to cause damage; if you have reduced kidney function, protein intake is genuinely a medical decision and belongs with your doctor rather than with a calculator.