How Many Calories Do I Need Every Day?

Your daily calorie requirement is shaped by two main components: your basal metabolic rate (BMR) — the energy your body burns simply staying alive at rest — and your activity level, which accounts for movement throughout the day. Together these give your total daily energy expenditure (TDEE), the number of calories you burn over a full day.

Key factors that affect your number

• Body size and composition: larger bodies and those with more muscle mass generally burn more calories at rest.
• Age: metabolic rate tends to slow gradually over time, so calorie needs often decrease with age.
• Biological sex: on average, males tend to have higher calorie needs than females, largely due to differences in muscle mass.
• Activity level: someone with a sedentary desk job needs fewer calories than someone who is on their feet all day or exercises regularly.

What about a calorie deficit for weight loss?

To lose weight, most guidance suggests consuming fewer calories than you burn — a calorie deficit. A modest, sustainable deficit is generally considered more effective than a very large one, which can lead to fatigue, muscle loss, and difficulty maintaining the approach. General educational guidance (for example, from NHS sources) often points to a deficit in the range of around 500 calories per day as a starting point, though individual needs vary. Always treat any general figure as a guide rather than a personal prescription, and discuss specific targets with your prescriber or doctor.

How GLP-1 medicines change the picture

People taking Mounjaro (tirzepatide) or Wegovy (semaglutide) commonly report a significant reduction in appetite and "food noise." This means many find they naturally eat less — sometimes considerably less — without consciously restricting intake. Tracking your actual calorie intake alongside your daily needs becomes especially valuable in this context: it helps you ensure you are still eating enough protein and nutrients even when appetite is low. For more on working out a starting figure, see our guide on how many calories you need a day, and for a deeper look at measuring what you actually eat, tracking the calories you consume is a helpful companion read.

How many calories for breakfast?

There is no universal rule, but many people find that spreading calories relatively evenly across meals — or front-loading slightly with a protein-rich breakfast — helps manage energy and hunger through the day. A common rough guide is that breakfast might account for roughly 20–25% of daily calories, though on a GLP-1 medicine your appetite at different times of day may shift considerably. The most useful approach is to track what you actually eat at each meal and see what pattern works for your body and routine.

For a fuller exploration of daily intake figures, our page on how many calories to eat a day covers this in more detail.

Knowing your daily calorie number is only useful if you can consistently compare it against what you are actually eating — and that is where logging becomes the practical tool. GLP Trackr's AI food photo scan is the fastest way to do this: point your camera at a meal and get an instant calorie and macro breakdown without manually searching every ingredient. It takes seconds, which matters when appetite is low and the last thing you want is friction around food logging.

Once your calorie target is set in the app, your daily check-in and targets dashboard shows at a glance how your intake compares to your goal — including protein, which is especially important on a GLP-1 journey to help preserve muscle alongside fat loss. The app also includes a barcode scanner and manual search for packaged foods, so whatever you are eating, logging it is straightforward.

Over time, the insights the app surfaces from your own data — correlations between intake, weight trends, and how you feel — can help you have much more informed conversations with your prescriber about what is working. The calorie calculator hub has more tools to help you get your numbers right.

Any specific calorie targets for your situation should be agreed with your prescriber or doctor, who can factor in your full health history. GLP Trackr helps you record and understand your intake — it is a tracking tool, not a substitute for professional guidance.

Ready to see your intake clearly every day? Download GLP Trackr on the App Store or Google Play and explore all the tracking features free for your first 7 days.