Calorie Calculator to Lose Weight on a GLP-1 Journey

A calorie calculator estimates the number of calories your body uses each day by combining two things: your Basal Metabolic Rate (BMR) — the energy your body needs just to function at rest — and your activity level. Multiply your BMR by an activity factor and you get your Total Daily Energy Expenditure (TDEE), which is roughly how many calories you need to maintain your current weight.

Creating a deficit for weight loss

To lose weight, most general guidance suggests eating below your TDEE. A modest deficit of around 500 calories per day is commonly referenced as a target that, for many people, supports a gradual, steady rate of loss — though individual results vary considerably depending on metabolism, activity, medication, and other factors. A detailed guide to how many calories support weight loss covers this in more depth.

What about steps?

Steps and daily movement contribute meaningfully to your overall calorie burn. A step calculator estimates the calories used from walking based on your step count, pace, and body weight. If you're aiming to increase activity as part of your journey, tracking steps alongside calories gives a fuller picture of your energy balance — something many people on GLP-1 medicines find motivating as appetite suppression creates more room to focus on movement.

How the BMR fits in

Your BMR is the foundation of any calorie target. Several formulas exist (Mifflin-St Jeor is widely used), and all of them use age, height, weight, and biological sex as inputs. Because your weight changes over time on a GLP-1 medicine, your BMR shifts too — which is one reason revisiting your calorie target periodically makes sense. See the maintenance calorie calculator for help finding your steady-state number as you progress.

General educational note: calorie calculators provide estimates, not precise prescriptions. Factors like lean muscle mass, hormonal status, gut health, and medication effects all influence actual energy use. Treat the output as a useful starting reference rather than a fixed rule, and discuss specific targets with your prescriber or a registered dietitian.

Knowing your calorie target is only useful if you can actually hit it day to day — and on a GLP-1 medicine, where appetite can be unpredictable, logging food manually can feel like friction you don't need. GLP Trackr's AI photo scan lets you point your camera at a meal and get an instant calorie and protein breakdown without typing a thing. It's one of the fastest ways to stay on top of your numbers when you're not very hungry and meal sizes are small.

Once you've used the calculator above to find your calorie goal, you can set that figure directly as a daily calorie target inside the app — alongside protein, water, fibre, and steps targets. Your morning check-in and food log feed into a running daily total, so you can see at a glance whether you're on track. The app's insights feature can also surface patterns over time, such as how your step count or protein intake relate to your week-on-week progress.

For a broader view of your energy balance and where your calorie target fits in your overall plan, the full calorie calculator hub brings together all the tools and guidance in one place.

GLP Trackr is designed specifically for people already on Mounjaro and Wegovy — so the targets, meal suggestions, and tracking tools are built around the realities of GLP-1 life: smaller portions, high-protein priorities, and progress that isn't always linear. Download free on the App Store or Google Play and explore it with a 7-day free trial.

The figures from any calorie calculator are general estimates. Always follow the personalised guidance of your prescriber or a registered dietitian — they can account for your full health picture in a way a calculator cannot.