What is a calorie deficit?

A calorie deficit means consuming fewer calories than your body burns in a day. Your Total Daily Energy Expenditure (TDEE) is the number of calories your body burns. If your TDEE is 2,400 kcal and you eat 1,900 kcal, you have a 500 kcal deficit. Over time, this deficit causes your body to burn stored fat for energy, resulting in fat loss.

How many calories should I cut to lose weight?

The evidence-based recommendation is a deficit of 300–500 kcal per day. This produces 0.3–0.5 kg of fat loss per week — sustainable, with minimal muscle loss. Larger deficits can accelerate short-term results but increase the risk of muscle loss, nutrient deficiencies, and metabolic slowdown. The best deficit is the largest one you can maintain consistently.

How much weight will I lose on a 500 calorie deficit?

A 500 kcal/day deficit produces approximately 0.45–0.5 kg of fat loss per week (about 1 lb), based on the estimate that 7,700 kcal equals 1 kg of fat. Over a month, this equals approximately 1.8–2 kg. Real-world results vary due to water retention, hormonal fluctuations, and changes in activity level.

What is the minimum calories I should eat?

Health organisations generally recommend no fewer than 1,200 kcal/day for women and 1,500 kcal/day for men, but these are conservative minimums — not targets. Most people do better with no more than a 500–750 kcal deficit from TDEE. Very low calorie diets should only be used under medical supervision.

Does a calorie deficit cause muscle loss?

All calorie deficits carry some risk of muscle loss alongside fat loss. The primary way to minimise muscle loss during a deficit is high protein intake (1.6–2.2g/kg of body weight) and continued resistance training. A moderate deficit (300–500 kcal) with adequate protein preserves the vast majority of muscle mass in most people.

How long will it take to lose weight on a calorie deficit?

Use the weeks-to-goal feature in the calculator. As a rough guide: losing 5 kg on a 500 kcal/day deficit takes approximately 10–11 weeks. Losing 10 kg takes approximately 22 weeks. Remember that the rate of loss slows over time as body weight decreases and TDEE drops — you may need to periodically recalculate your deficit.

What is a calorie deficit?

A calorie deficit means consuming fewer calories than your body burns in a day. Your Total Daily Energy Expenditure (TDEE) is the number of calories your body burns. If your TDEE is 2,400 kcal and you eat 1,900 kcal, you have a 500 kcal deficit. Over time, this deficit causes your body to burn stored fat for energy, resulting in fat loss.

How many calories should I cut to lose weight?

The evidence-based recommendation is a deficit of 300–500 kcal per day. This produces 0.3–0.5 kg of fat loss per week — sustainable, with minimal muscle loss. Larger deficits can accelerate short-term results but increase the risk of muscle loss, nutrient deficiencies, and metabolic slowdown. The best deficit is the largest one you can maintain consistently.

How much weight will I lose on a 500 calorie deficit?

A 500 kcal/day deficit produces approximately 0.45–0.5 kg of fat loss per week (about 1 lb), based on the estimate that 7,700 kcal equals 1 kg of fat. Over a month, this equals approximately 1.8–2 kg. Real-world results vary due to water retention, hormonal fluctuations, and changes in activity level.

What is the minimum calories I should eat?

Health organisations generally recommend no fewer than 1,200 kcal/day for women and 1,500 kcal/day for men, but these are conservative minimums — not targets. Most people do better with no more than a 500–750 kcal deficit from TDEE. Very low calorie diets should only be used under medical supervision.

Does a calorie deficit cause muscle loss?

All calorie deficits carry some risk of muscle loss alongside fat loss. The primary way to minimise muscle loss during a deficit is high protein intake (1.6–2.2g/kg of body weight) and continued resistance training. A moderate deficit (300–500 kcal) with adequate protein preserves the vast majority of muscle mass in most people.

How long will it take to lose weight on a calorie deficit?

Use the weeks-to-goal feature in the calculator. As a rough guide: losing 5 kg on a 500 kcal/day deficit takes approximately 10–11 weeks. Losing 10 kg takes approximately 22 weeks. Remember that the rate of loss slows over time as body weight decreases and TDEE drops — you may need to periodically recalculate your deficit.

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Calorie Deficit Calculator

Find your ideal daily calorie deficit for safe, sustainable fat loss. See weekly projections, safety rating, and macro suggestions — all based on your personal TDEE.

How Calorie Deficits Work

A calorie deficit occurs when you consume fewer calories than your body burns. This energy shortfall forces the body to draw on stored fat as fuel, leading to fat loss over time.

The relationship between deficits and fat loss is governed by the energy density of fat — approximately 7,700 kcal per kilogram of body fat. A daily deficit of 500 kcal therefore produces roughly 0.5 kg of fat loss per week (3,500 kcal ÷ 7,700 ≈ 0.45 kg).

The key to effective fat loss is choosing a deficit size that is sustainable without causing muscle loss, nutritional deficiencies, or excessive hunger. Research consistently supports a deficit of 300–500 kcal/day as the optimal range for most people. Deficits above 1,000 kcal/day risk muscle loss, hormonal disruption, and metabolic adaptation.

This calculator takes your Total Daily Energy Expenditure (TDEE) as the baseline. If you don't know your TDEE, calculate it using our TDEE Calculator first.

Formula, sources and limitations

How this estimate is produced

Published method

Implemented method: Deficit = TDEE − Daily Calories

Sources

A new predictive equation for resting energy expenditure in healthy individuals
American Journal of Clinical Nutrition, 1990

Important limitations

The result compounds uncertainty from predicted TDEE and simplified energy-balance assumptions.
Real weight change is not perfectly linear and should be monitored conservatively.

A citation describes the source method; it does not mean this website or its implementation has been clinically validated or independently reviewed. See the methodology, editorial policy, and medical disclaimer.

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