How Many Calories Should I Be Eating Per Day on a GLP-1 Medicine?

Calorie needs are calculated from a few key inputs. Your Total Daily Energy Expenditure (TDEE) — the number of calories your body uses in a day — is the starting point. A modest deficit below that number is what drives gradual weight loss over time.

The main factors involved

• Basal Metabolic Rate (BMR): the calories your body burns at rest, keeping vital functions running. This depends on height, weight, age, and biological sex.
• Activity level: a sedentary day burns far fewer calories than an active one. Most calorie calculators apply a multiplier (sedentary, lightly active, moderately active, very active) to BMR to arrive at TDEE.
• Body composition: more muscle mass generally means a higher resting metabolic rate.

What changes on a GLP-1 medicine?

Reduced appetite is one of the most commonly reported effects of medicines like Mounjaro (tirzepatide) and Wegovy (semaglutide). Many people find they naturally eat less — sometimes significantly less — without trying. While this can support a calorie deficit, eating too little over time can lead to fatigue, muscle loss, and nutritional gaps. A general guideline from dietetic practice is to avoid consistently eating below around 1,200 kcal per day for women or 1,500 kcal for men without clinical supervision, though your own target should be discussed with your prescriber or a registered dietitian.

Protein deserves particular attention. Many people on GLP-1 medicines are advised to prioritise protein at each meal to help protect muscle mass during weight loss — explore practical guidance on how many calories to consume daily and think about how protein fits into that total.

For a closer look at how daily needs translate meal by meal, the page on how many calories breakfast should be is a useful companion to this one. You can also read more on eating the right number of calories daily for a broader framing of the topic, or explore all the tools on our calorie calculator hub.

Knowing your target is one thing — hitting it consistently, especially when appetite fluctuates from day to day on a GLP-1 medicine, is another. GLP Trackr's AI food photo scan makes logging effortless: point your camera at a meal and the app estimates calories, protein, and macros instantly, without manual searching or guesswork.

Once you have your daily calorie goal in mind, you can set it as a target inside the app. Your food log feeds into that target in real time, so you can see at a glance whether you are on track — useful on days when appetite is low and it is easy to under-eat without realising. The app also tracks protein separately, which matters on a GLP-1 journey where protecting muscle is a priority.

If you want a deeper view of your patterns over time, the insights and analytics features can help surface correlations — for example, how your calorie intake on a given day relates to your energy levels or weight trend across the week.

GLP Trackr is a tracking tool, not a clinical nutrition service. For personalised calorie targets tailored to your health history and goals, speak with your prescriber, doctor, or a registered dietitian — they are best placed to advise you.

Ready to make food logging on your GLP-1 journey genuinely simple? GLP Trackr is free to try for 7 days — download it on the App Store or Google Play and see how quickly your numbers start making sense.