Caloric Deficit: What It Means on a GLP-1 Journey and How to Calculate Yours

Your body burns a certain number of calories each day just to keep things running — breathing, circulation, digestion, movement. This is broadly called your Total Daily Energy Expenditure (TDEE). When you eat fewer calories than your TDEE, your body draws on stored energy, and over time that typically results in weight loss.

A moderate deficit is generally considered most sustainable

A commonly referenced range is a daily deficit of roughly 500 calories below your TDEE, which many nutrition frameworks associate with a gradual, manageable rate of loss. Larger deficits are not automatically better — they can increase the risk of muscle loss, fatigue, and nutrient gaps, especially when appetite is already suppressed by a GLP-1 medicine. Your actual target should be agreed with your prescriber or a registered dietitian who knows your full picture.

GLP-1 medicines change the equation a little

Because Mounjaro (tirzepatide) and Wegovy (semaglutide) reduce appetite and slow gastric emptying for many people, it can become easy to eat far too little without realising it. Tracking your intake against a calculated target helps you stay in a deliberate, healthy range rather than simply eating as little as your appetite allows. For a deeper look at how daily intake figures are calculated, see our guide on calorie intake calculation and our page on how to calculate your caloric needs.

What goes into the calculation

A basic caloric deficit calculation uses your estimated TDEE — itself based on factors like height, weight, age, sex, and activity level — and subtracts a target deficit. The result is an approximate daily calorie target. These are estimates, not prescriptions; individual metabolism varies, and the numbers are a starting point for experimentation and discussion with your healthcare team. You can also explore a full breakdown of these inputs on our caloric deficit guide.

Calculating a deficit is one thing; consistently hitting your target day after day is where most people struggle — particularly when appetite fluctuates on a weekly injection schedule. GLP Trackr is built specifically for this.

AI food scanning does the heavy lifting

The most relevant feature here is GLP Trackr's AI photo scan: point your camera at a meal and the app instantly estimates calories, protein, and macros without manual data entry. When appetite is low and meals are small, the last thing you want is friction around logging. Barcode scanning and a searchable food database are also available for packaged foods and ingredients.

Set your deficit target and watch it in real time

Once you have your calorie target from the calculator above, you can set it directly inside GLP Trackr. The app tracks your running daily total and shows how much headroom you have left — so you can see at a glance whether you are on track, under-eating, or getting close to your limit. Protein targets work the same way, which matters because adequate protein helps preserve muscle during a deficit.

For a broader view of all the calorie tools available on GLP Trackr, visit our calorie calculator hub.

A note on individual variation

The figure this calculator produces is an educational estimate. It is not a personalised medical recommendation. If you have any health conditions, are adjusting your activity level, or are concerned that your intake feels too low or too high, speak with your prescriber or doctor before making changes — they can factor in your full health history in a way a calculator cannot.

Ready to stop guessing and start tracking? Set your calorie target in GLP Trackr and let the AI scanner log your meals in seconds. Available free on the App Store and Google Play — your first 7 days are on us.