How to Calculate Your Caloric Needs on Mounjaro or Wegovy

Calculating your caloric needs means estimating the total energy your body uses in a day, often called your Total Daily Energy Expenditure (TDEE). This figure combines your Basal Metabolic Rate (BMR) — the energy your body needs simply to function at rest — with the energy burned through daily movement and activity.

Why this matters specifically on Mounjaro or Wegovy

Medicines like Mounjaro (tirzepatide) and Wegovy (semaglutide) reduce appetite and food noise, which is part of how they support weight management. However, many people find that their appetite drops so significantly that they struggle to reach even a reasonable calorie floor. Without tracking, it can be hard to know whether you are eating enough protein, enough overall energy, or whether you are inadvertently under-fuelling your body.

General educational guidance from nutrition science suggests that most adults need a meaningful calorie intake to preserve muscle mass, support energy, and keep the metabolism functioning well — and that very low intakes over long periods can work against those goals. That said, the right caloric target for you specifically is something to discuss with your prescriber or a registered dietitian, as individual needs vary widely.

How caloric calculations work

Most TDEE estimates use a formula — such as the Mifflin-St Jeor equation — that takes your weight, height, age, and an activity multiplier into account. The result is a starting estimate, not a fixed prescription. Factors like how your body responds to the medicine, your activity level, and your personal goals all influence what a useful daily calorie range might look like for you.

If you want to explore the numbers in more depth, take a look at the full calorie calculator for GLP-1 users, or dig into the practical side of building a caloric deficit — understanding the gap between intake and expenditure is a logical next step once you have your baseline figure.

You can also explore the caloric calculator tool to run your own estimate, or read more about what a caloric deficit means in practice for someone on a GLP-1 medicine.

Calculating your caloric needs is only half the picture — the other half is knowing what you are actually eating day to day. That is where GLP Trackr's AI food scanning makes a real difference. Rather than manually entering every meal, you can point your phone camera at a plate and get an instant breakdown of calories, protein, and macros. When appetite is low and meals are smaller, this kind of effortless logging matters.

Once you have a rough daily calorie target in mind (whether from a calculator or discussed with your healthcare team), GLP Trackr lets you set that as a personal target and tracks your progress against it throughout the day. The app also includes a protein target alongside calories, which is especially useful on a GLP-1 medicine where hitting adequate protein in smaller meals can be a genuine challenge.

The insights dashboard then shows you patterns over time — days when intake dropped very low, how calorie trends align with your weight progress, and where consistency is strongest — so you can have genuinely informed conversations with your prescriber or dietitian.

Always follow the guidance of your prescriber or doctor when it comes to specific dietary targets. GLP Trackr helps you capture the data to inform those conversations — it is not a substitute for personalised clinical advice.

Ready to put the numbers to work? Download GLP Trackr on the App Store or Google Play and explore it free for your first seven days — no commitment required.