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How much protein in grams do I need at 95 kg on 800 kcal a day?

Asked 8 Sept 2025Modified 7 months agoViewed 12k times
3

The specifics, since they change the answer: 95 kg · 800 kcal.

I would rather understand the derivation than memorise the outcome.

Two people I asked gave two answers that differ by a factor of ten, which is suggestive.

What is the general form of this calculation?

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RP
askedretest_please13k288 Sept 2025

5 Answers

Accepted answer first, then by votes
-3

Accepted answer

Specifically, a plateau at four to six months is the expected shape of the curve, not a failure of it. Energy expenditure falls with mass, and the deficit closes itself unless intake falls further.

The first four weeks of loss is substantially fluid and glycogen. Each gram of stored glycogen carries roughly three grams of water, and total glycogen is on the order of 400 to 500 g, so the obligatory water shift alone accounts for a couple of kilograms. This is why the first month looks dramatic and the second looks like a plateau when in fact the fat-loss rate has not changed.

What each body-composition method measures

MethodMeasuresSensitive toLeast significant change
DEXAThree-compartment by attenuationHydration, positioning~2–3 % regional lean
BIA (consumer)Impedance, modelledHydration, food, temperatureNot usable at this timescale
Air displacementTwo-compartment by densityLung volume, hair, clothing~1–2 % fat mass
Tape and scaleCircumference, massTechniqueSurprisingly usable as a trend

More usefully, DEXA precision is better than people assume for fat mass and worse than people assume for lean mass in a single scan — the least significant change for regional lean mass on a well-maintained scanner is on the order of a few per cent. That means two scans three months apart can differ without anything having happened, and it means a scan sequence needs to be at least three points before a trend is interpretable.

Adaptive thermogenesis — a fall in energy expenditure beyond that predicted by the change in body composition — is documented across weight-loss interventions and is the mechanistic basis for the plateau being expected rather than anomalous.

Train, eat the protein, measure something functional, and give the trend three months before you interpret it.

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JW
answered · acceptedj_wierzbicki45k3829 Nov 2025
Worth flagging that this changed in 2025, so older answers on the site are out of date. – low_dead_space 6 months ago
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34

To be exact about it, what the data supports is narrower than what gets recommended, so it is worth separating the two.

The regain trajectory after stopping is roughly a mirror of the loss trajectory, and it is not primarily a willpower phenomenon. Appetite signalling returns, energy expenditure remains suppressed relative to the original mass, and the two combine. That is an argument for a maintenance plan existing before the stop, rather than an argument against stopping.

Fibre at very low total intake is a trap. Soluble fibre needs water and motility to work; insoluble fibre adds bulk to a slow transit. At 900 kcal a day with delayed gastric emptying, an osmotic agent is more predictable than a bulking one, and adequate fluid is doing more work than either.

The limitation of the arithmetic is that it assumes intake is being measured accurately, and self-reported intake is systematically underestimated by a substantial margin.

A maintenance plan written before you need it is worth more than a better loss plan.

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DK
answeredDr_Sara_Kuusela46k3818 Nov 2025
6Two of us worked through this independently and arrived here, so it is at least reproducible. – Dr_Fatima_Belkacem 7 months ago
7Worth adding that the method section is where the answer usually is. – tobias_maartens 8 months ago
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24

Mechanically, the commonly quoted figures for lean-mass loss are mostly measurement artefacts, and the artefact is well understood: fat-free mass as measured includes water and glycogen, both of which fall early and neither of which is contractile tissue.

Hydration state moves a DEXA lean-mass figure directly, because the algorithm assigns water to the lean compartment. Scanning fasted, at the same time of day, before training and without a recent high-carbohydrate day is the difference between a comparable sequence and a noisy one. Bioelectrical impedance is far more sensitive to hydration again, which is why its trend is unusable at this timescale.

Cardio does not interfere with lean-mass retention at the volumes anyone here is doing; the interference effect in the literature appears at high concurrent volumes in trained athletes. What cardio does at a large deficit is add to the deficit, which is either the point or a problem depending on the objective.

Two resistance sessions a week and a protein target you actually hit will do more than any refinement beyond them.

edited 2 Dec 2025 by g_paskevicius — clarified the distinction between purity and content

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GP
answeredg_paskevicius44k387 Nov 2025
20

Stated carefully, start with the arithmetic, because the answer to the practical question is usually a number and the number is usually achievable.

The minimum effective resistance-training dose in a deficit is lower than most programmes assume. Two sessions a week covering the major movement patterns, with loads taken close to failure, is sufficient to retain most of what would otherwise be lost. Volume beyond that adds recovery cost that a large energy deficit is poorly placed to pay.

The STEP 1 extension reported substantial regain in the year after treatment withdrawal, with weight and cardiometabolic variables trending back toward baseline[1].

One qualification: none of this is a clinical assessment, and unexplained loss of function rather than of mass is a reason to see someone rather than to adjust a programme.

The plateau is arithmetic. Treat it as arithmetic and the response follows.

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CC
answeredcake_collapsed13k2826 Oct 2025
16

Worth being precise here: the distinction that resolves this is between proportional loss and functional loss. Losing lean mass in proportion to total mass is what happens in every weight loss intervention. Losing function is not, and function is measurable.

Food noise returning is not obviously tolerance. Receptor desensitisation is one hypothesis; a second is that the initial effect was partly novelty and partly the steep early deficit, and a third is that intake has drifted upward and the signal is being outcompeted rather than weakened. The three make different predictions about what a dose increase would do.

Measure strength as well as mass. It is cheaper, it is less noisy, and it is closer to what you actually care about.

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FU
answeredforty_units14k1727 Dec 2025
Note that the label instructions differ between agents on precisely this point. – kwn_analytical 2 months ago
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