How Many Calories Does It Take to Lose a Stone?

The 3,500-calories-per-pound figure is a widely used general estimate, not a precise biological law — real weight loss involves water, muscle, hormones, and metabolic adaptation. Still, it gives a useful starting framework: a stone is 14 lb, so the ballpark total deficit is around 49,000 calories.

How long does it take?

Spread that deficit over time and the picture becomes clearer:

• A 500-calorie daily deficit produces roughly 1 lb per week — reaching a stone in approximately 14 weeks (around 3.5 months).
• A 750-calorie daily deficit shortens that to around 9–10 weeks.
• A 250-calorie daily deficit — more realistic on days when appetite is very low — would take closer to 28 weeks.

These figures are general illustrations, not personal targets. The right deficit for any individual depends on their total daily energy expenditure, current intake, activity level, and medical history. For a personalised view of how your own numbers stack up, the guide to how many calories it takes to lose weight walks through the broader picture.

Losing a stone in a month: is it realistic?

To lose a stone in a month would require a deficit of roughly 1,600 calories every single day. For most adults that is extremely difficult to sustain safely, and rapid loss of this kind typically includes water weight and some muscle alongside fat. A more moderate, consistent deficit over 10–14 weeks is generally considered more sustainable — though your prescriber or doctor is best placed to discuss what a healthy rate looks like for you specifically.

Why GLP-1 medicines change the equation

Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only medicines that act on appetite-regulating pathways, and many people find their daily calorie intake drops significantly — sometimes without trying. That can accelerate a deficit, but it also makes it easy to under-eat protein and key nutrients. Understanding what calories actually are and how they work can help you stay nourished even when appetite is low. It is also worth knowing how the calories-per-pound conversion works in practice, so your expectations stay grounded as the weeks go by.

Keeping a mental tally of a 49,000-calorie goal is impractical — but logging daily intake consistently is not, especially with the right tool. GLP Trackr's AI food photo scan lets you point your camera at a meal and get an instant calorie and protein breakdown, which is particularly useful when portions are small and appetite unpredictable on a GLP-1 medicine.

Once your daily calorie target is set in the app, GLP Trackr tracks progress against it automatically — combining manual entries, barcode scans, and photo scans into a running daily total. The weight logging and weekly progress charts then connect your intake data to what is actually happening on the scale, so you can see whether your deficit is landing where you expected.

For a broader look at the calculations that feed into all of this, the GLP Trackr calorie calculator hub brings together the key tools in one place.

GLP Trackr is a tracking and journaling app — it helps you observe and record your journey, not replace the guidance of your prescriber or doctor. If you have questions about what calorie intake is right for you, or whether your rate of loss is appropriate, bring your logged data to your next appointment and discuss it with your healthcare professional.

Ready to start connecting your food intake to your progress? Download GLP Trackr on the App Store or Google Play and explore it free for 7 days — no commitment needed.