The particulars: 81 kg · 800 kcal.
I would like the arithmetic checked rather than the conclusion asserted.
I have deliberately not used an online calculator because I want to be able to check the result.
What is the general form of this calculation?
130 to 178 g a day. The range the resistance-training literature supports is 1.6 to 2.2 g per kilogram, which at 81 kg is 130–178 g. At 4 kcal per gram that is 518–713 kcal, or 65–89 per cent of a 800 intake — which is why protein has to be planned first at this energy level rather than fitted in afterwards. Split it across three or four servings; roughly 0.4 g/kg per meal saturates the synthetic response and the surplus in one large serving does not carry over.
Answer first: aim for 1.6 to 2.2 grams per kilogram of reference body weight per day, distributed across three or four servings, and treat it as the first constraint on the day rather than the last.
Use reference or adjusted body weight rather than total weight where adiposity is substantial: a common approach is ideal body weight plus a quarter of the excess, which avoids targets that no one could eat.
High protein intakes do not damage healthy kidneys in the published evidence; existing kidney disease is a genuine exception and is a clinical question.
Systematic reviews of high-protein intake in people with normal renal function have not found evidence of harm to kidney function.
Targets are population estimates; individual requirements vary and there is no cheap way to measure yours.
1.6 to 2.2 g/kg of reference weight, split three or four ways. That is the answer.
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsThe honest answer is that most people in a deficit fall well short, and closing that gap matters more than any refinement above it.
The leucine threshold for triggering the response is around two and a half to three grams per meal. Thirty grams of most animal protein reaches it; thirty grams of many plant proteins does not, which is why plant-based targets run higher.
Put another way, appetite suppression makes protein-rich foods harder to eat because they are satiating. Liquid protein and leaner, less voluminous sources are the usual practical workaround.
Leucine threshold effects are documented across protein sources and explain the difference in per-serving requirements between animal and plant proteins.
Healthy kidneys tolerate this fine. Diseased ones are a clinical question.
The short version: total daily protein first, per-meal distribution second, timing a distant third.
A practical construction: 30 to 40 grams at each of three meals plus a 20 to 30 gram snack covers most targets without any protein powder at all.
Hydration requirements rise modestly with protein intake because urea excretion increases, which is a real effect and a small one.
Meta-analytic estimates place the plateau of the dose-response for lean-mass retention with resistance training around 1.6 g/kg, with a confidence interval extending to about 2.2.
Nothing here is dietetic or medical advice.
Plant-based patterns need a higher total and more attention per serving.
Start with which body weight the target is calculated from, because using total weight in someone with substantial adiposity inflates the number without benefit.
Per meal, roughly 0.4 grams per kilogram saturates the synthetic response in most adults, which is about 30 to 40 grams for a typical person. Beyond that the surplus is oxidised or used for other purposes rather than adding to synthesis.
Stable-isotope feeding studies establish the per-meal saturation of muscle protein synthesis at around 0.4 g/kg in young adults and higher in older ones.
The caveat is that anyone with chronic kidney disease has a genuinely different protein calculation and needs it done by a clinician.
Plan protein first in the day; with suppressed appetite it will not happen otherwise.
Plant-based patterns need somewhat higher totals and more attention to leucine content per serving to produce an equivalent response.
Older adults need more per meal to overcome anabolic resistance, with 1.2 to 1.5 g/kg daily commonly quoted for maintenance and more in a deficit.
The body-composition substudies in the major programmes consistently report that the proportion of weight lost as fat mass is approximately three quarters or better, with the lean-mass fraction falling within the range seen in dietary weight loss of comparable magnitude[1].
Per-meal saturation is real. One enormous serving does not do the job of three.
edited 16 Jun 2025 by Dr_Rosalind_Achebe — corrected a unit error in the worked example
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