How to Calculate Your Calorie Deficit

The Short Answer

A calorie deficit occurs when you consistently consume less energy than your body uses.

To estimate a deficit, first estimate your maintenance calories. Then create a moderate reduction rather than immediately cutting food as aggressively as possible.

Step 1: Estimate Your BMR

BMR means Basal Metabolic Rate.

It estimates the energy your body uses at rest.

One commonly used equation is the Mifflin-St Jeor equation.

For men:

BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5

For women:

BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

This is an estimate, not a laboratory measurement.

Step 2: Estimate Maintenance Calories

Your actual daily energy expenditure is higher than your BMR because you also:

• Walk
• Work
• Exercise
• Digest food
• Perform daily activities

An activity multiplier can be used to estimate total daily energy expenditure.

This is commonly called TDEE.

Step 3: Create a Moderate Deficit

Once you have an estimated maintenance level, you can reduce calorie intake.

For example, if your estimated maintenance is:

2,400 kcal/day

you might begin with approximately:

2,000 to 2,200 kcal/day

rather than immediately dropping to an extremely low intake.

The appropriate deficit depends on your body size, goals, activity and circumstances.

Why Your Calculation Won't Be Perfect

Calorie calculators estimate.

Your actual energy expenditure can differ because of:

• Genetics
• Activity
• Body composition
• Training
• Daily movement
• Metabolic adaptation
• Changes in body weight

This is why your real-world weight trend is useful.

Monitor the Trend

Do not judge your deficit based on one morning's weight.

Body weight changes because of:

• Water
• Food in the digestive system
• Sodium
• Glycogen
• Hormonal changes
• Actual body tissue

Look at the trend over several weeks.

Don't Make the Deficit Too Aggressive

A very large deficit can make it harder to:

• Train effectively
• Eat enough protein
• Recover
• Maintain muscle
• Manage hunger
• Sustain the diet

Fat loss is not a race.