How long will it take to lose weight?
The time it takes to reach your goal depends on how much you want to lose and the size of your daily calorie deficit. A safe, sustainable pace for most adults is 0.25–1 kg (0.5–2 lb) per week. This free weight loss calculator estimates your daily calorie target, the number of weeks needed and the date you could reach your goal weight.
How the weight loss calculator works
- Maintenance calories: your BMR is estimated with the Mifflin-St Jeor equation and multiplied by your activity level to get your TDEE.
- Calorie deficit: about 7,700 kcal equals 1 kg of body fat, so losing 0.5 kg a week needs a deficit of about 550 kcal a day (0.5 × 7,700 ÷ 7). Your daily target is TDEE minus this deficit, but never below 1,200 kcal (women) or 1,500 kcal (men).
- Realistic simulation: instead of a straight line, the calculator recalculates your TDEE every day as your weight falls. Because a lighter body burns fewer calories, weight loss slows down over time — just like in real life.
Example: a 35-year-old man, 180 cm, 90 kg and sedentary, eating about 550 kcal below maintenance, would take roughly 23 weeks to reach 80 kg — longer than the simple estimate of 20 weeks, because his calorie needs drop as he loses weight.
Weight loss pace: low, normal and high
| Rate of loss | Daily deficit | Level | What to expect |
|---|---|---|---|
| 0.25 kg (0.5 lb) a week | ~275 kcal | Slow | Easy to sustain; good when close to goal weight |
| 0.5 kg (1 lb) a week | ~550 kcal | Recommended | Best balance of results and sustainability for most people |
| 0.75 kg (1.5 lb) a week | ~825 kcal | Fast | Suitable if you have a lot of weight to lose; needs high protein |
| Over 1 kg (2 lb) a week | 1,100+ kcal | Too fast | Higher risk of muscle loss, gallstones, fatigue and regain — only under medical supervision |
In the first one or two weeks you may lose more because of water and glycogen. After that, a steady rate is normal.
Benefits of a realistic weight loss plan
- Health gains start early: losing just 5–10% of your weight can lower blood pressure, blood sugar, cholesterol and fatty liver, and improve PCOS symptoms.
- Less frustration: knowing that progress slows naturally helps you keep going.
- Muscle protection: a moderate deficit with enough protein preserves muscle and metabolism.
- Better long-term results: slow, steady loss is more likely to stay off.
Health warnings
- Do not follow very low-calorie diets (under 800–1,000 kcal) without medical supervision.
- People with diabetes (especially on insulin or sulfonylureas), heart, kidney or liver disease, or a history of eating disorders should get medical advice before dieting.
- Do not try to lose weight during pregnancy or breastfeeding without your doctor’s guidance.
- Unexplained weight loss — losing weight without trying — needs a medical check.
- Rapid weight loss raises the risk of gallstones, hair loss and nutrient deficiencies.
Tips to reach your goal faster — safely
Hit your protein target, fill half your plate with vegetables, walk 7,000–10,000 steps a day and add 2–3 strength sessions a week. Plan for weekends and family gatherings, swap sugary drinks for water and sleep 7–9 hours. If you have insulin resistance or PCOS, our guides to the insulin resistance diet and PCOS meal plan can help. Read more about sustainable weight loss strategies.
Frequently asked questions
How much weight can I lose in a month?
Most people can safely lose about 2–4 kg (4–8 lb) a month by eating 500–750 kcal less than their maintenance calories. You may lose a little more in the first month because of water loss.
Why is my weight loss slowing down?
As you lose weight, your body needs fewer calories, so the same intake creates a smaller deficit. Water retention, hormones and less daily movement can also slow the scale. Recalculate your calories every 4–5 kg.
Is 7,700 calories really equal to 1 kg of fat?
It is a widely used approximation of the energy stored in 1 kg of body fat. Real weight loss also includes water and some lean tissue, so the calculator is an estimate, not a guarantee.
Is it better to diet or exercise for weight loss?
Both help, but diet usually has the bigger effect on weight loss, while exercise helps keep muscle, improves fitness and is key to keeping weight off.
What if my goal date is too far away?
Set smaller goals. Losing 5–10% of your weight first brings real health benefits and is easier to achieve. Then set a new goal from there.
Sources
- Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet 2011;378:826–837.
- Mifflin MD, St Jeor ST, et al. Am J Clin Nutr 1990.
- NHS. Losing weight – getting started.
- NICE guideline: Overweight and obesity management.