Calorie calculator
A gentle, evidence-based starting point. We estimate your maintenance calories and suggest a modest deficit, no crash targets.
How the estimate works
The calculator uses the Mifflin-St Jeor equation, the formula most dietitians reach for first. It estimates your resting metabolism from weight, height, age and sex, then scales it by your activity level to give maintenance calories. We subtract 500 kcal a day, a deficit that supports roughly 0.5 kg of loss a week without triggering the extreme hunger that crashes most diets.
If you are on GLP-1 treatment
Mounjaro, Wegovy and the daily tablets lower appetite directly, so many people land in a deficit without counting anything. In that case, treat this number as a ceiling to stay under comfortably, not a goal to chase. What matters more is what those calories contain: our protein guide shows how to protect muscle while eating less.
When to ignore the number
Do not force a deficit if you feel faint, constantly cold, or obsessed with food. Those are signs to eat more and message the clinical team. And if you have a history of disordered eating, skip calorie targets entirely and work with your prescriber on structure instead.
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Weight loss plans from £69 a month
Mounjaro, Wegovy, the Wegovy pill and the Foundayo pill. Each plan covers the medicine, prescriber review, monthly check-ins and tracked delivery.
Check if treatment suits youFree health check. You pay nothing until a prescriber approves.
Check your eligibilityAbout this page
- Written by
- Able Clinic editorial team
- Clinical review
- Pharmacy team at Curb Healthcare Ltd, GPhC 9012581
- Last reviewed
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