What is a calorie deficit?

A calorie deficit occurs when you consume fewer calories than your body burns (TDEE). This forces your body to use stored energy (fat) for fuel, leading to weight loss. A deficit of 500 calories per day typically results in about 0.45kg (1lb) of weight loss per week.

How big should my calorie deficit be?

A moderate deficit of 500 calories per day is generally recommended for sustainable weight loss (about 0.5kg/1lb per week). Mild deficits (250 cal) are slower but easier to maintain. Aggressive deficits (750+ cal) can lead to faster results but may cause muscle loss and are harder to sustain.

What is the minimum safe calorie intake?

General guidelines suggest men should not eat below 1,500 calories/day and women below 1,200 calories/day without medical supervision. Very low calorie diets can lead to nutrient deficiencies, muscle loss, metabolic slowdown, and other health issues.

How long will it take to reach my goal weight?

This depends on how much weight you need to lose and your daily deficit. This calculator provides a timeline estimate. As a rule of thumb, 1kg of body fat contains about 7,700 calories, so a 500-calorie daily deficit would take about 15 days per kg of weight loss.

Will a calorie deficit cause muscle loss?

Some muscle loss can occur during a calorie deficit, but you can minimize it by: maintaining adequate protein intake (1.6-2.2g/kg), doing resistance training, keeping the deficit moderate (not extreme), and getting enough sleep.

Should I exercise more or eat less?

The most effective approach combines both. Creating your deficit through diet alone can be hard to sustain, while exercise alone often does not create enough deficit for meaningful weight loss. A combination of reduced calorie intake and increased activity is ideal.

Free Calorie Deficit Calculator

Calculate your daily calorie target for weight loss and see how long it will take to reach your goal weight.

Calculator

Enter your details to calculate your daily calorie target for weight loss.

Understanding Calorie Deficits

A calorie deficit is the difference between the calories your body burns (TDEE) and the calories you consume. When you eat fewer calories than you burn, your body uses stored energy (primarily body fat) to make up the difference, resulting in weight loss.

How This Calculator Works

1. BMR = Mifflin-St Jeor equation

2. TDEE = BMR x Activity Multiplier

3. Target = TDEE - Daily Deficit

4. Timeline = Weight to Lose x 7,700 kcal/kg / Daily Deficit

Deficit Comparison

DeficitWeekly LossSustainability

250 cal (mild)~0.25 kgHigh

500 cal (moderate)~0.5 kgGood

750 cal (aggressive)~0.75 kgChallenging

Tips for Success

Prioritize protein (1.6-2.2g per kg) to preserve muscle

Include resistance training to maintain lean mass

Track your intake consistently — what gets measured gets managed

Stay hydrated — sometimes hunger signals are actually thirst

Medical Disclaimer

This calculator provides estimates for informational purposes only. Individual calorie needs vary based on metabolism, health conditions, and other factors. Consult a healthcare provider or registered dietitian before starting any weight loss program, especially if you have medical conditions.

Free Calorie Deficit Calculator

Understanding Calorie Deficits

How This Calculator Works

Deficit Comparison

Tips for Success

Medical Disclaimer

Frequently Asked Questions

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