How Many Calories Deficit Do You Need to Lose Weight?

A calorie deficit is the gap between the energy your body needs to maintain its current weight (your total daily energy expenditure, or TDEE) and the calories you actually consume. When that gap exists consistently over time, your body draws on stored energy — typically body fat — to make up the difference.

What affects how large your deficit should be?

• Starting point: A larger body typically burns more calories at rest, meaning the same deficit represents a smaller percentage of total needs. As weight changes, so does the calculation.
• Activity level: More movement increases the calories your body burns, widening the potential deficit without requiring you to eat less.
• Metabolic adaptation: Over time, the body can adjust its energy expenditure in response to prolonged restriction — one reason progress is rarely perfectly linear.
• Protein intake: Higher protein intake supports muscle retention during a deficit, which matters for body composition and long-term metabolic rate.

General deficit ranges to know about

Many guidelines suggest a moderate deficit — broadly in the range of 300–600 calories per day — as a sustainable starting point for gradual, steady loss. Deficits at the larger end (above 750–1,000 calories) are generally associated with faster but less sustainable loss, greater muscle loss risk, and more pronounced fatigue or nutrient shortfalls. These are general educational ranges; the right deficit for you is something to work out with your prescriber or doctor, particularly when you are taking a prescribed medicine that already influences appetite and intake.

How GLP-1 medicines interact with your calorie intake

Medicines like Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescribed GLP-1 receptor agonists that commonly reduce appetite and increase feelings of fullness in many people who take them. This can make it easier to eat in a deficit — but it can also make it harder to notice when intake drops very low, which is why tracking actual numbers tends to be more informative than relying on appetite cues alone. For more on daily calorie targets, see our guide on how many calories you actually need each day and our related page on how many calories to aim for when losing weight. You can also explore how many calories you must eat in a day for a practical breakdown of minimums and targets.

Knowing your target deficit is one thing — seeing whether you are actually hitting it day to day is another. GLP Trackr's food logging feature is built to make this effortless, even when appetite is low and meals are small.

The quickest way to log is with the AI photo scan: point your camera at a meal and get an instant breakdown of calories, protein, and macros without typing a single thing. For packaged foods, the barcode scanner handles the entry in seconds. You can also set a personal calorie target inside the app and see your running total update throughout the day, so you always know where you stand against your deficit goal.

Beyond food, the daily check-in captures your weight each morning alongside mood, energy, and food-noise levels — giving you a fuller picture of how your deficit is actually affecting you, not just what the numbers say.

All of this feeds into the app's insights, so you can start to see patterns: how different intake levels relate to your weekly results, and whether your deficit is sitting in a range that seems to be working for your body. That kind of personal data is also genuinely useful to bring to your prescriber or doctor at your next review — a clear log is worth far more than a rough recollection. You can explore the full range of calorie and nutrition tools in our calorie calculator hub.

Any decision about the right calorie level or deficit size for your specific situation should be made with your healthcare professional — they understand your full medical picture in a way no general guideline can.

Ready to see your deficit in real time? Download GLP Trackr on the App Store or Google Play and start a free 7-day trial — snap a photo of your next meal and let the numbers take care of themselves.