How much weight should I lose per week?

About 0.625% of body weight — half a kilogram a week at 80 kg. Faster than about three-quarters of a percent costs muscle, and muscle is the point of the cut.

How big should the deficit be?

−17.5% of maintenance, and never below −25% whatever a calculator says. Month6 enforces that floor before it shows a number, and will not set a deficit at all under 18 or under a BMI of 18.5.

How much fat can I lose in 6 months?

For a 32-year-old man, 178 cm, 76 kg, 20% body fat: about 9.4 kg of fat by month six, to roughly 9% body fat. Heavier people lose more in absolute terms, leaner people less — the rate is a share of body weight, and it slows near the floor.

Why does the projection flatten out?

Fat loss tapers to zero at 8% body fat for men and 16% for women — inside the American Council on Exercise's "athletes" band, well clear of essential fat. The arithmetic is not allowed to run you into a 2% body.

Guides

How fast can you lose fat without losing muscle?

Short answer

About 0.625% of body weight a week — half a kilogram at 80 kg — on a deficit of −17.5% from maintenance, never deeper than −25%, with 2.2 g of protein per kg. Fat loss slows to a stop at 8% body fat for men and 16% for women.

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

What a six-month cut looks like — 32-year-old man, 178 cm, 76 kg, 20% body fat

The projection core run on one example (invented, labelled as such), read at each milestone. An estimate that assumes at least 80% adherence to the plan.

Projected fat lost, body weight and body-fat percentage at months 3, 6 and 12
Month	Fat lost	Body weight	Body fat
Month 3	−5.9 kg	70.1 kg	13%
Month 6	−9.4 kg	66.7 kg	9%
Month 12	−9.9 kg	66.1 kg	8%

Why not faster

A deficit is a trade: the body takes the shortfall from fat if it can, and from muscle if you push it. The evidence from athletes cutting slowly against quickly is consistent — the slow group kept, and even added, lean mass while the fast group lost it. 0.625%of body weight a week is the slow group's rate, and the −25% floor is the line below which that trade stops being worth it.

Protein is the other half

In a deficit protein does the most to hold on to muscle, which is why the target rises to 2.2 g/kg while cutting — see how much protein per day.

Questions

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

Your own numbers

See your own six-month cut as a figure — free, in your browser, nothing sent anywhere.

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

Month6 plots your weekly weigh-in against this curve, says whether you are ahead or behind, and moves your calories by a bounded step — never past the floor.