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How much protein in grams do I need at 68 kg on 1,000 kcal a day?

Asked 24 May 2026Modified 1 min agoViewed 4.8k times
5

What I have: 68 kg · 1,000 kcal.

This should be a straightforward calculation and I keep getting two different answers.

The numbers are arbitrary; the method is what I am after.

Can someone walk through the arithmetic step by step?

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SW
askedswab_and_wait15k1824 May 2026

5 Answers

Accepted answer first, then by votes
6

Accepted answer

What the data supports is narrower than what gets recommended, so it is worth separating the two.

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.

On the detail: 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.

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.

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

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TI
answered · acceptedteodora_ilic15k2830 May 2026
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2

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

Protein target, worked: at 88 kg, a target of 1.6 g/kg is 88 × 1.6 = 141 g per day. Spread across three eating occasions that is roughly 47 g each, and the leucine threshold for a maximal muscle protein synthetic response is met at around 2.5 to 3 g of leucine, which corresponds to roughly 30 to 40 g of a high-quality protein. So three meals at 40 g plus one 25 g snack gets you to 145 g and clears the per-meal threshold each time. On 900 kcal that leaves about 340 kcal for everything else, which is the actual constraint.

Worth being precise here: 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 caveat is that population averages tell you about populations. Your own trajectory is a sample of one and should be read as a trend, not as a deviation from a published mean.

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

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DF
answeredDr_Nadia_Farsi90k2586 Jun 2026
2This is the first explanation of that which has actually made sense to me. – label_claim 5 months ago
3Note that the label instructions differ between agents on precisely this point. – m_haraldsen 6 months ago
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2

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.

Absolute strength holds up better than scale weight during a deficit for a straightforward reason: strength is substantially neural and skill-based, and the contractile tissue you retain is being trained harder relative to its size. Grip strength and repetition maxima are therefore lagging indicators of muscle loss rather than leading ones, which is an argument for measuring both.

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

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M4
answeredmz_411399k25813 Jun 2026
5The placebo-arm figure is the part everyone omits. – Dr_Bram_Verhoeven 3 months ago
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2

In practice, the mechanism is worth having straight, because it predicts which interventions can work and which cannot.

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 evidence for a higher protein intake preserving lean mass during an energy deficit is reasonably strong in resistance-trained populations and weaker in sedentary ones, with the meta-analytic estimates supporting intakes in the region of 1.6 g/kg over lower intakes when training is present[1].

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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DV
answereddead_volume49k3820 Jun 2026
I would add a sentence about sterility here, since it is the thing people skip. – ines_brandt 1 days ago
The placebo-arm figure is the part everyone omits. – pierce_count 2 months ago
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Put another way, 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.

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.

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.

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

edited 6 Aug 2026 by low_dead_space — clarified the distinction between purity and content

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LS
answeredlow_dead_space42k3811 Jul 2026
3The distinction between purity and content cannot be repeated often enough here. – Dr_Elias_Weiss 8 months ago
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