What does your body actually need?

This gives you a starting point, not a rule. Numbers here are estimates, use them as a rough guide alongside how you actually feel.

GUIDE ONLY
This calculator is a general guide only. It is not medical or dietary advice, and it is not meant to be used without advice from a qualified health professional such as your GP, prescriber or an Accredited Practising Dietitian. This matters even more if you're using a GLP-1 medicine (like Mounjaro or Ozempic), are pregnant or breastfeeding, have a history of disordered eating, or are managing a health condition.
This isn't about the number on the scale

These figures are information, not a verdict on your worth or your effort. A healthy body isn't a number, a macro split, or a dress size, it's one with energy to get through your day, comfort in your own skin, strength for the things you love, and freedom from constantly thinking about food. Chronic dieting and weight stigma are consistently linked to worse health outcomes than the weight itself. If anything here ever makes you feel smaller instead of more informed, close the tab and go do something that feels good in your body instead.

Use your current weight, not your goal weight. Your BMR reflects the body you have right now. Recalculate every 4-5kg lost (or every few weeks) rather than aiming at a future number upfront.

BMR (energy at rest) -
TDEE (maintenance calories) -
A gentle range, not a strict target
Mild deficit (slow, sustainable loss)-
Maintenance-
Mild surplus (gentle gain)-

Calculated using the Mifflin-St Jeor equation, generally considered the most accurate estimate for everyday use. It's a starting point for the {BODY} pillar of your life, not a verdict. Adjust based on real results over a few weeks.

Life stage
Macro & fibre guide for your stage of life
Mild deficit
Protein-
Carbohydrates-
Fat-
Maintenance
Protein-
Carbohydrates-
Fat-
Mild surplus
Protein-
Carbohydrates-
Fat-
Fibre target25-28g/day

GLP-1 guide (GUIDE ONLY, check with your prescriber or dietitian)
  • Protein first. A 2025 joint advisory on nutrition for GLP-1 therapy puts adequate protein and strength training at the centre of protecting muscle while you lose weight. Protein here is set at 1.5 g per kg of your current weight, within the roughly 1.2 to 1.6 g/kg range commonly quoted for GLP-1 users. At higher body weights, a dietitian may work from an adjusted or goal weight instead, which gives a lower number.
  • Don't chase a lower calorie number. These medicines already reduce appetite, and eating too little makes muscle loss more likely. The calorie figures above are estimates, not a goal to undercut.
  • Fibre, fluids and strength. Aim for your fibre target, drink regularly, and include some resistance or strength work if you can.
  • Side effects or struggling to eat? Talk to your prescriber. Don't adjust your medicine or your eating based on this page.
Did you know?

The BMI wasn't created by a doctor and was never meant to judge anyone's individual health. Belgian mathematician and astronomer Adolphe Quetelet devised it in the 1830s (originally the "Quetelet Index") to find the statistical average build of a population, not to assess any one person, and his data came almost entirely from white European men. It doesn't account for muscle, bone density, age, sex or ethnicity, which is a big part of why modern research shows it's a poor stand-alone measure of an individual's health. That's why this calculator leaves BMI out altogether and focuses on energy needs and nourishment instead.

Sourced from peer-reviewed research and clinical guidance:
This calculator is a general guide only, built from publicly available research. It is not personalised medical or dietetic advice and isn't a substitute for care from your GP, endocrinologist, or an accredited practising dietitian, particularly if you're managing a health condition, taking medication, pregnant, or breastfeeding. If something here doesn't match what your own body or your health team tells you, trust them first.
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