What does bulking actually change?

Calories +12.5%, protein 1.8 g/kg, the scale +0.375% of body weight a week — and the engine caps each week so no more fat is added than muscle. For a 21-year-old man, 178 cm, 63 kg, never lifted that is about +5.8 kg of muscle by month six.

What does cutting change?

Calories −17.5%, protein up to 2.2 g/kg, the scale −0.625% of body weight a week. For a 32-year-old man, 178 cm, 76 kg, 20% body fat that is about −9.4 kg of fat by month six.

That is a recomp: maintenance calories, 2 g/kg protein, the scale held flat while shape moves. Slower on each front — for a 27-year-old woman, 165 cm, 62 kg, 28% body fat about +1.4 kg muscle and −1.4 kg fat by month six — but it never asks you to get heavier or hungrier.

When will the app refuse a cut?

Under 18, or under a body-mass index of 18.5. It shows the recomp curve instead and says why. That is a safety rule, not a judgement.

Guides

Should you bulk or cut first?

Short answer

Bulk if you are skinny or skinny-fat and after visible muscle for the first time; cut if there is fat you want gone and you are not underweight; recomp if the scale is fine and the mirror is not. A bulk is maintenance +12.5% and +0.375% of body weight a week; a cut is −17.5% and −0.625% of body weight a week; a recomp holds both.

Numbers computed from the Month6 engine; last checked 5 October 2026.

One engine, three settings

Calories, protein and weekly weight change by goal
Goal	Calories	Protein	Scale, per week
Build muscle (bulk)	+12.5%	1.8 g/kg	+0.375% of body weight
Lose fat (cut)	−17.5%	2.2 g/kg	−0.625% of body weight
Both (recomp)	maintenance	2 g/kg	0

Nothing else differs. The training plan, the check-in and the projection are the same arithmetic; only these three numbers move.

Six months of each, on an example body

Projected change by month six for three example bodies
Example	Goal	Muscle	Fat
21-year-old man, 178 cm, 63 kg, never lifted	Bulk	+5.8 kg	—
32-year-old man, 178 cm, 76 kg, 20% body fat	Cut	—	−9.4 kg
27-year-old woman, 165 cm, 62 kg, 28% body fat	Recomp	+1.4 kg	−1.4 kg

Invented examples, labelled as such; estimates that assume at least 80% adherence. On a bulk the card prints muscle only and on a cut fat only, because that is the number each phase is for.

The bulk that does not make you fat

A surplus of +12.5%is modest on purpose, and the engine caps each week's gain so that no more fat is added than muscle. A beginner's rate fills that cap; a slower gainer is held to a smaller surplus. That is why an experienced lifter's bulk projects a smaller weight change than the surplus alone would suggest.

Questions

An estimate for healthy adults, not medical advice. How every number is made, with its citations: Sources & method.

Your own numbers

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See your six-month body. Then go earn it.

In Month6 the three goals are one engine with different targets — switch at any time, and the six-month curve, the protein ring and the plan move together.