How much protein in grams do I need at 112 kg on 900 kcal a day?

Conditions: 112 kg · 900 kcal.

I want the working, not the result — I need to be able to redo it with different numbers.

I care about the precision as well as the value — I want to know how many figures are real.

Where is my error, and what is the correct working?

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.

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.

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.

Nothing here is dietetic or medical advice.

1.6 to 2.2 g/kg of reference weight, split three or four ways. That is the answer.

edited 21 Jun 2025 by sian_llewellyn — fixed an arithmetic slip in the third paragraph

More usefully, plant-based patterns need somewhat higher totals and more attention to leucine content per serving to produce an equivalent response.

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.

High protein intakes do not damage healthy kidneys in the published evidence; existing kidney disease is a genuine exception and is a clinical question.

Targets are population estimates; individual requirements vary and there is no cheap way to measure yours.

Healthy kidneys tolerate this fine. Diseased ones are a clinical question.

The honest answer is that most people in a deficit fall well short, and closing that gap matters more than any refinement above it.

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.

Per-meal saturation is real. One enormous serving does not do the job of three.

Start with which body weight the target is calculated from, because using total weight in someone with substantial adiposity inflates the number without benefit.

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.

Plant-based patterns need a higher total and more attention per serving.