How do you calculate calories and macros for a cut?

1. Estimate your resting energy expenditure from your profile

Gather your age, height and current weight. Then add your everyday activity and training: these will help you move from resting expenditure to total expenditure.

The Mifflin–St Jeor equation estimates resting energy expenditure in adults. In its simplified form:

• Men: resting expenditure = 10 × weight + 6.25 × height − 5 × age + 5.
• Women: resting expenditure = 10 × weight + 6.25 × height − 5 × age − 161.

Weight is in kilograms, height in centimetres and age in years. The result is in kilocalories per day.

This result is not your calorie intake target for a cut. It only estimates your resting expenditure, rather than representing your whole day. The equation does not measure your metabolism and cannot perfectly reflect every individual's circumstances.

References: [1][2][3]

2. Estimate maintenance calories, then set the deficit

A common method is to apply an activity factor to resting expenditure:

Estimated maintenance calories = resting expenditure × activity factor.

Choose this factor from a method that explains its categories. Describe your actual week: desk-based or physical work, travel, and the frequency and duration of your training sessions. Describe training and activity outside training separately.

Also check whether training is already included in the calculation. Adding it again, for example using data from a watch, can count the same activity twice.

Your starting target then becomes:

Calorie target for a cut = estimated maintenance calories − chosen deficit.

The deficit is not a universal amount to subtract for everyone. Favour a cautious reduction suited to your profile and training load, rather than the lowest possible target. If you already have food records and a relatively stable weight, these observations can help you check whether your estimate is plausible.

References: [2][3][4]

3. Calculate protein, then fat, then carbohydrates

Macronutrients, or “macros”, here refer to protein, fat and carbohydrates. To allocate them, start with the calorie target chosen in the previous step.

Set protein first. If your personalised guideline is expressed in grams per kilogram, the calculation is:

Protein in grams = reference body weight × personalised protein guideline.

The guideline and reference body weight you use must take your circumstances into account. Do not automatically copy someone else's target.

Set fat next. Use your personalised guideline, expressed in grams or as a share of daily energy. If you do not yet have these guidelines, establish them using a documented method or with a sports dietitian, rather than inventing a split.

Finally, allocate the remaining energy to carbohydrates. This simplified calculation uses the general Atwater factors presented by the FAO: 4 kcal per gram of protein, 4 per gram of carbohydrate and 9 per gram of fat:

Carbohydrates in grams = [target calories − (protein in grams × 4) − (fat in grams × 9)] ÷ 4.

Here, these factors only convert grams into energy within the formula; they do not set your individual targets. If the result is negative, or leaves an amount of carbohydrate that is difficult to reconcile with your sport, review all the parameters rather than forcing the result.

References: [5]

4. Check the calculation for consistency before preparing meals

This check identifies inconsistencies in the method; it does not prove that the estimate matches your actual needs.

References: [2][3][4][5]

5. Test your targets against a week of real meals

Before treating your numbers as usable, compare them with your habits. Choose a training day and a day without a session, then check how they fit into your week.

Illustrative editorial example: you want to keep a lunch of chicken, rice and courgettes cooked in olive oil. Log every ingredient with the quantities you actually plan to use, then look at what remains for your other meals. Do not count only the chicken and rice: the oil and side dishes are part of the calculation too.

Use reference data that match the state in which the food is weighed, raw or cooked. Recalculate substitutions too: replacing an ingredient does not automatically preserve the same macros.

Finally, check practical constraints: a packed lunch, a late dinner, eating out, preparation time and your usual spending. If hitting your targets requires an unrealistic catch-up meal every evening, your organisation or macro split needs another look.

For the next step, see the guide to a cutting meal plan for strength training.

References: [5][6]

6. Adjust based on tracking, not a single weigh-in

Record what you actually consume, not just the planned menu. Also observe your weight under comparable conditions, your hunger, your recovery and how training sessions go.

Compare weight readings taken under the same conditions over time. Check for missed food entries, portion differences and changes in activity before changing the parameters.

If an adjustment seems necessary, change one parameter at a time so you can understand its effect. The NHS advises seeing a doctor if unexplained tiredness lasts for several weeks or affects daily life. This guide cannot identify its cause.

References: [2][3][4][7]

References: [8][9]

Turn targets into meals with Sthenia

Sthenia, the sports nutrition app from JB Labs, the publisher of this guide, can help you take the next step from nutritional targets to organised meals.

Its calculation method documented as of 23 October 2026 uses Mifflin–St Jeor by default and ten Haaf–Weijs for endurance sports from five training sessions per week. Targets take account of your profile, sport, training frequency and goal. These remain estimates, not measurements of metabolism or clinical validation of the app. The scientific references used do not mean that all new studies are automatically incorporated.

The food diary and manual calorie and macronutrient tracking are free and unlimited. The paid Pro plan adds a personalised seven-day meal plan and an associated grocery list with quantities.

Meal macros depend on quantities and available reference data; incomplete matching can underestimate the total. The practical aim is to reduce planning work while checking targets against what you actually eat.

References: [10][11][12]