Calorie and Macro Calculator: Know Your Numbers on a GLP-1 Journey

A calorie and macro calculator estimates two things: how many calories your body needs each day to support your goals, and how those calories should be distributed across protein, carbohydrates, and fat. On a GLP-1 journey, protein is the macro most worth paying attention to — many people find that reduced appetite makes it easy to under-eat protein, which can affect muscle maintenance alongside fat loss.

How the calculation works

Most calculators start with your total daily energy expenditure (TDEE) — an estimate of calories burned based on body size, age, and activity level — then apply a modest deficit if your goal is fat loss. General educational guidance suggests deficits in the range of 300–500 calories per day are considered moderate, though the right figure for any individual is something to confirm with your prescriber or doctor rather than set independently.

Protein targets are often expressed as a range per kilogram (or pound) of body weight. A commonly cited general range for people trying to preserve muscle during weight loss is roughly 1.2–1.6 g per kg of body weight, but this varies with age, activity, and health status — treat any figure from a calculator as a starting reference, not a clinical prescription.

Why macros matter on Mounjaro or Wegovy

Both Mounjaro (tirzepatide) and Wegovy (semaglutide) influence appetite and the feeling of fullness, which changes how much people naturally eat. This makes intentional macro tracking particularly useful: rather than simply eating less, the aim is to eat better within a smaller intake — prioritising protein and fibre-rich foods that support satiety and nutrition. For practical food ideas to pair with your targets, explore our guidance on counting macros day to day and our free calorie and macro tracker overview.

For a broader look at calorie needs on a GLP-1 programme, see the calorie calculator hub.

Calculating your targets is only step one — hitting them consistently is where most people struggle, especially when appetite fluctuates from week to week. GLP Trackr is built specifically for this: once you set your calorie and protein targets inside the app, every meal you log counts toward them automatically.

AI photo scan — the fastest way to log a meal

The standout feature for food tracking is the AI photo scan: point your camera at a plate and the app returns an instant calorie and macro breakdown, no manual searching required. On low-appetite days when you are eating small, irregular meals, this removes the friction that causes most people to stop logging altogether. Barcode scanning and a searchable food database are also available for packaged foods and ingredients.

Targets and daily check-in

Set your calorie, protein, and other macro targets in GLP Trackr and the app tracks your running totals through the day. The daily check-in also captures weight, mood, energy, and food-noise levels — so over time you can see how your nutrition patterns connect to how you feel and how your progress moves. For a deeper look at app options in this space, see our comparison of the best apps for calorie and macro tracking.

As always, the numbers from any calculator are a general starting point. Your prescriber or doctor is the right person to advise on specific nutrition targets for your situation — GLP Trackr helps you track and report accurately, not replace that guidance.

Ready to put your numbers to use? Download GLP Trackr on the App Store or Google Play and start your free 7-day trial — log your first meal in under a minute.