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Nutrition

Protein and calorie calculator

This is the exact calculation Train Smart runs to set your daily targets: the Mifflin-St Jeor resting-energy equation, an activity multiplier, and a protein target anchored to bodyweight.

How to use it

Weight and height in metric. Choose the activity level that matches a typical week, not your best one. "Athlete" means training most days at genuine intensity.

The rate of change is capped at 1 kg per week in either direction, and the calculator will not return a target below about 1.2× your resting requirement — going lower costs training quality and, in a deficit, muscle.

The detail

What the number means

Where each number comes from

  • Resting energy: the Mifflin-St Jeor equation (Mifflin & St Jeor, American Journal of Clinical Nutrition, 1990).
  • Protein: 1.8–2.2 g per kg of bodyweight, at the higher end in a deficit — the range supported by the ACSM/Dietitians of Canada joint position statement on nutrition and athletic performance and the ISSN position stand on protein and exercise.
  • Fat: 25% of total calories, a conventional practical anchor rather than a research finding.
  • Carbohydrate: whatever is left, which is how a fuelling-first approach works in practice.
  • The 1.2× floor: a safety limit, not a target. It stops the calculator returning an aggressive deficit for a light athlete.

Full citations for all of these are on our sources page.

What a target does not do

It does not cook. The gap between knowing your protein target and hitting it four days a week is the entire problem, and it is not solved by a more precise number.

Train Smart's meal plans take these targets and build an actual week from a library of 188 meals — filtered by the equipment you own, the cooking difficulty you will actually attempt, and any foods you have excluded — then produce a prep-day cook list and a shopping list from it.

FAQ

Common questions

How much protein do I need as an athlete?
Around 1.8–2.2 g per kilogram of bodyweight per day, spread across meals rather than concentrated in one. The higher end applies when you are in a calorie deficit, because protein is what protects muscle when energy is short.
Is the Mifflin-St Jeor equation accurate?
It is the most widely validated of the resting-energy prediction equations, but it is a population estimate — individuals vary. Use it as a starting point, then adjust based on what your weight actually does over two to three weeks.
Why does the calculator refuse very aggressive deficits?
Because below roughly 1.2× your resting requirement, training quality falls off and muscle loss accelerates. The calculator raises the target to that floor and tells you it has done so.
Keep reading

Related

Sports nutrition basics

The four things that account for nearly all of the result at community level.

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Nutrition in Train Smart

Meal plans, prep-day cook lists and shopping lists built from your targets.

Open

Sources

Every nutrition claim on this site, with the paper behind it.

Open

Or let the app do it every week

Train Smart runs this calculation continuously — recalculating your working weights, your conditioning paces and your load every session, without you opening a calculator.

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