How much protein in grams do I need at 112 kg on 1,100 kcal a day?

Conditions: 112 kg · 1,100 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.

Is my approach right even if my number is wrong?

179 to 246 g a day. The range the resistance-training literature supports is 1.6 to 2.2 g per kilogram, which at 112 kg is 179–246 g. At 4 kcal per gram that is 717–986 kcal, or 65–90 per cent of a 1,100 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.

Answering this needs to know whether appetite is suppressed, because in this class the practical problem is achieving intake rather than choosing a target.

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.

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.

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.

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

Specifically, the relevant physiology is the per-meal saturation of the synthetic response, which is why one large serving does not substitute for three moderate ones.

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.

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.

Research-use compounds are not approved for human use, and no supplement substitutes for total intake.

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

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

Hydration requirements rise modestly with protein intake because urea excretion increases, which is a real effect and a small one.

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.

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

Plan protein first in the day; with suppressed appetite it will not happen otherwise.

Protein is also the most satiating macronutrient per kilocalorie, which makes hitting the target easier than it sounds once it is prioritised.

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.

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.

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

edited 8 Dec 2024 by fib4_reader — added the method parameters

More usefully, this is one of the better-evidenced areas in nutrition and the disagreements are about the top of the range, not the bottom.

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.

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