How to Work Out Your Maintenance Calories

Maintenance calories are not a fixed number — they shift as your weight, age, and activity level change, which is particularly relevant if you are losing weight on Mounjaro or Wegovy. Most estimates start with a calculation called the Basal Metabolic Rate (BMR), which approximates how many calories your body burns at complete rest to keep basic functions running.

A commonly used approach: the Mifflin-St Jeor equation

One widely referenced formula for estimating BMR is the Mifflin-St Jeor equation. It uses your current weight (in kg), height (in cm), and age (in years), with a small adjustment for biological sex. Once you have a BMR estimate, you multiply it by an activity factor — ranging roughly from 1.2 for a largely sedentary day to around 1.7 for a highly active one — to arrive at your Total Daily Energy Expenditure (TDEE). This TDEE figure is what most people mean when they say "maintenance calories."

What shifts your maintenance number

• Body weight: as your weight changes, your BMR changes with it — recalculating every few weeks gives a more accurate picture.
• Lean muscle mass: muscle burns more calories at rest than fat tissue, so body composition matters alongside the scale.
• Activity level: reduced appetite from GLP-1 medicines can sometimes reduce energy and movement — honest self-assessment here improves accuracy.
• Age: metabolic rate tends to decline gradually over time.

Equations like these are population-based estimates, not precise individual measurements. They give a useful starting point, but your actual maintenance may be somewhat higher or lower. For a structured way to work through the numbers, the maintenance calorie calculator on GLP Trackr walks you through the inputs step by step. You can also read more about what maintenance calories actually mean and how they fit into a GLP-1 weight-loss plan.

If you want to explore the relationship between your maintenance figure and a calorie deficit, the calorie deficit guide covers how that gap works in practice.

Knowing your maintenance calories on paper is only half the picture — the more useful step is comparing it against what you actually eat each day. This is where many people find the gap between intention and reality becomes clear, and where a tool designed for GLP-1 life makes a meaningful difference.

GLP Trackr's AI photo-scan food logging is worth trying if manual entry feels tedious: point your phone camera at a meal and the app estimates the calories and macronutrients for you. For packaged foods, the barcode scanner pulls nutrition data directly. Both approaches feed into your daily calorie total automatically, so you can see at a glance how your intake compares with your estimated maintenance figure — without spreadsheets or mental arithmetic.

Once you have set a calorie target in the app (based on your calculated maintenance, minus whatever deficit you and your prescriber have discussed), the daily check-in takes about thirty seconds: log your weight, energy, and food-noise level alongside your food, and over time the app builds a picture of how your intake, your progress, and how you feel are connected. The step-by-step guide to calculating your maintenance calories on GLP Trackr explains how to feed those numbers into your tracking routine.

A reminder worth keeping in mind: a calorie target is a general educational guide, not a personalised medical prescription. If you have questions about the right calorie level for your specific situation — particularly alongside a GLP-1 medicine — your prescriber or doctor is the right person to ask. They have the full picture of your health history that a calculation alone cannot capture.

Give the food logging a go — GLP Trackr is free to try for 7 days on the App Store and Google Play. Snap your meals, set your targets, and start seeing the numbers that actually reflect your journey.