Protein Intake Calculator

The Recommended Dietary Allowance for protein is 0.8 g per kilogram of bodyweight. It is widely read as "how much protein you should eat", and it is not that. The RDA is defined as the amount sufficient to meet the requirements of 97–98% of healthy people — that is, the amount below which deficiency becomes likely.² It is a floor set to prevent a problem, derived from nitrogen balance studies, and it says nothing about the intake that produces the best body composition.

The distinction matters because the gap is large. Morton and colleagues pooled 49 randomised trials covering 1,863 participants and found that protein supplementation meaningfully increased strength and lean mass gains from resistance training, with benefits plateauing at about 1.6 g/kg per day — twice the RDA.¹ Above that, the meta-regression found no additional effect.

The one situation where pushing protein clearly above 1.6 g/kg pays off is energy restriction. When calories are short, the body will draw on muscle as well as fat, and a high protein intake plus resistance training is what tips that balance.

Longland and colleagues ran the cleanest test of this. Participants were put in a steep deficit for four weeks with matched training, split between 2.4 g/kg and 1.2 g/kg of protein. The high-protein group lost more fat and gained 1.2 kg of lean mass; the lower-protein group merely held theirs.³ Same deficit, same training — the protein was the variable.

Total daily intake matters most by a wide margin. After that, distribution matters a little, and timing matters least of all — the "anabolic window" of thirty minutes after training has not survived scrutiny.⁶

• Spread it across 3–4 meals. Roughly 0.4 g/kg per meal appears to maximise the muscle protein synthesis response. Eating 150 g in one sitting is not wasted, but it is less efficient than splitting it.
• Get some within a few hours of training. Not thirty minutes — the window is measured in hours, and total daily intake dominates anyway.
• Animal sources are more complete. They contain all essential amino acids in useful ratios and are richer in leucine, the main trigger for muscle protein synthesis.
• Plant sources work, with attention. Combine across the day — legumes with grains — and aim slightly higher in total, since plant proteins are typically less digestible and lower in leucine.
• Before bed is genuinely useful. 30–40 g of a slow-digesting protein before sleep improves overnight muscle protein synthesis, one of the few timing findings that has held up.

This deserves a direct answer because the myth is persistent and it puts people off an intake that would help them.

In people with existing kidney disease, restricting protein can slow progression, and that is standard clinical advice. The error is generalising it. In people with healthy kidneys, there is no evidence that high protein intake causes damage. Martin and colleagues reviewed the literature specifically on this point and concluded that the concern is not supported for healthy individuals.⁵ The rise in glomerular filtration rate seen with higher intake is a normal functional adaptation, not injury.

The requirement moves in the opposite direction to what most people assume. Older muscle is anabolically resistant — it responds less to a given dose of protein — so more is needed to produce the same effect.

The PROT-AGE study group recommends at least 1.0–1.2 g/kg for healthy older adults, 1.2–1.5 g/kg for those with acute or chronic illness, and more still for those doing resistance training.⁴ Set against an RDA of 0.8, that is a substantial gap — and it lands on the population most at risk from losing muscle, where the consequence is falls and loss of independence rather than a slower gym progression.

• Pair it with resistance training. Protein without a training stimulus does much less at any age, and the effect is starker in older adults.
• Front-load breakfast. Older adults typically eat most of their protein at dinner; spreading it more evenly improves the total daily synthesis response.
• Track lean mass, not just weight with the Lean Body Mass Calculator.

A gram target is abstract until you can see it on a plate. These are the same figures the macro, carbohydrate and fat calculators use, so the numbers agree wherever you meet them on this site.

Two things tend to surprise people here. Animal sources concentrate protein far more densely than plant sources, so a plant-based target usually needs legumes and soy foods deliberately rather than incidentally. And the everyday foods that feel protein-rich — a slice of bread, a cup of milk — contribute much less than a single serving of meat, fish or tofu.