How to count calories on a cut

Written by Norbert Grzenkowicz · 15 October 2026

Estimate maintenance with the Mifflin-St Jeor equation times an activity factor, then subtract enough to lose 0.5-1% of bodyweight a week, the rate Helms and colleagues recommend for natural bodybuilders dieting, to keep as much muscle as possible. Set protein first, then fats, then carbs, and weigh and log your food, oil and sauces included. After two to three weeks, once you have at least two weekly average weights, compare them and adjust the target.

Step 1: maintenance calories

The Mifflin-St Jeor equation estimates resting energy expenditure. For men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5. For women, replace "+ 5" with "− 161". It was built from measurements of 498 healthy adults aged 19 to 78, of normal weight and with obesity, so for you it is an estimate, not a measurement.

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Multiply the result by a physical activity level (PAL). The FAO/WHO/UNU report groups lifestyles into three bands: sedentary or light 1.40-1.69, active 1.70-1.99, vigorous 2.00-2.40. It calls values above 2.40 difficult to keep up for long.

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The report gives office workers as an example of a sedentary lifestyle, and says an hour a day of moderate to vigorous exercise raises average PAL from 1.55 to 1.75. If you work at a desk and train a few times a week rather than every day, start in the bottom band. Mifflin estimates resting expenditure while the report's PAL multiplies basal metabolic rate, so the result is an approximation.

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Step 2: size the deficit as a rate of loss

Helms, Aragon and Fitschen, reviewing the evidence for natural bodybuilders in contest prep, recommend setting calories to lose about 0.5-1% of bodyweight a week. They note that the bigger the deficit, the larger the share of lost weight that comes from lean mass, so a slower rate may protect muscle better. They cite a study where athletes losing 0.7% a week did better than those losing 1.4%.

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To turn a rate into calories you need a conversion. The common rule is about 7,700 kcal per kilogram (32.2 MJ/kg). Hall shows the rule roughly fits people with obesity who start with more than 30 kg of body fat, and overstates the deficit needed per kilogram for people with less. The example man has about 12 kg of fat at 80 kg and 15%, so use the rule as a starting point and let the scale check it.

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Step 3: protein, then fats, then carbs

Protein: Helms and colleagues give 2.3-3.1 g per kg of lean body mass a day for most bodybuilders on a cut.
Fats: 15-30% of your energy intake. Go to the low end, 15-20%, when more fat would push protein or carbs below their range.
Carbs: what is left of the target after protein and fats.

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For the protein detail, a table by bodyweight and the split across meals, see the guide on protein on a cut.

Step 4: adjust after two to three weeks

One weigh-in does not tell you your rate. Weigh yourself in the morning several times a week and average each week. After two or three weeks you have two or three averages, and the change between them is your rate.

Helms and colleagues write that the intake you start a cut on will need adjusting over time as bodyweight drops and the body adapts. If your rate is slower than planned, lower calories; if it is faster than 1% a week, raise them.

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How to count what you eat

Weigh food on a kitchen scale instead of judging portions by eye.
Log the weight in the same state as the database entry or label: raw weight against a raw entry, cooked against cooked.
On labels, read the values per 100 g and scale them to your portion.
Log oil, butter and sauces as separate items, like the rest of the meal.

Common mistakes

Counting from your day-one weight for the whole cut. In the Mifflin equation each kilogram is 10 kcal of resting expenditure, so after losing 4 kg at PAL 1.7 maintenance drops by about 70 kcal a day. Recalculate every few kilograms.
Not logging oil and sauces. Olive oil has about 884 kcal per 100 g (USDA), so 10 g in the pan is about 88 kcal. Two unlogged 15 g pours a day add about 265 kcal, more than half of the 440 kcal deficit in the example.
Weekend drift. If you eat 1,100 kcal over your 2,630 kcal target on Saturday and Sunday, the weekly deficit falls from 3,080 to 880 kcal, and the rate from 0.4 kg to about 0.1 kg a week.

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How CalXd does it

CalXd calculates your daily calorie and macro targets from your profile and goal. You can also set the calorie target yourself. Log a meal by photo, voice, text or barcode. You log your weight and see it on a chart with a 7-day average line.

At most once every 7 days, CalXd reads your weight trend over the last 3 weeks. When there is enough data, it suggests a new calorie target and you decide whether to apply it. The first suggestion comes no earlier than 4 weeks into a goal. With a calorie target you set yourself, there are no suggestions.

Questions

How many calories should I eat on a cut?

Enough to lose 0.5-1% of bodyweight a week, the rate Helms and colleagues recommend for natural bodybuilders dieting, to keep as much muscle as possible. Estimate maintenance with Mifflin-St Jeor times an activity factor and subtract the deficit that matches that rate. For 80 kg at 0.5% a week that is about 440 kcal a day, using 7,700 kcal per kilogram.

How big should my calorie deficit be?

Work it out from the rate, not from a fixed number. 0.5% a week at 80 kg is 0.4 kg, about 440 kcal a day; 1% is about 880 kcal. Hall shows the 7,700 kcal per kilogram rule overstates the deficit needed for lean people, so check the result on the scale after two to three weeks.

When should I change my calories on a cut?

When the weekly averages over two to three weeks show a rate outside 0.5-1% of bodyweight. Do not change the target after a single weigh-in. Every few kilograms lost, also recalculate maintenance, because in the Mifflin equation each kilogram is 10 kcal of resting expenditure.

Do I need to log cooking oil and sauces?

Yes. Olive oil has about 884 kcal per 100 g according to USDA, so 10 g is about 88 kcal. A few unlogged pours a day can eat most of a deficit.

Sources

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