Protein calculator: how many grams of protein a day

How many grams of protein a day: why the RDA is a floor

The recommended allowance of 0.8 g per kilogram is the amount that prevents deficiency in most healthy adults. That is a different question from how much is optimal, and the two get conflated constantly. Nobody sets their vitamin C intake at the level that merely prevents scurvy.

For anyone training, losing weight, or over about 65, the evidence supports more. The ranges above come from that literature rather than from the deficiency threshold.

Protein intake for weight loss

Two reasons, and they compound. Protein is the most satiating macronutrient per calorie, so a higher intake makes the same deficit easier to hold. And in an energy deficit the body will take amino acids from muscle unless there are enough coming in — adequate protein plus resistance training is what decides whether the weight you lose is fat or muscle.

Protein for muscle gain, and where the ceiling is

Above roughly 2.2 g per kilogram, controlled trials stop showing additional benefit for muscle retention or growth in most people. Higher intakes are not dangerous for healthy kidneys — that claim has been tested repeatedly and does not hold up — but they displace other food and cost more.

The exception that matters: existing kidney disease genuinely does change the recommendation, and that is a conversation with a doctor rather than a calculator.

Spreading protein intake across the day

Spreading protein across three or four meals of roughly 25 to 40 g stimulates muscle protein synthesis better than the same total eaten mostly at dinner, which is the pattern most people actually have. Breakfast is usually where the gap is. There is more on sources and supplements in the protein article.