Calorie Deficit
A calorie deficit occurs when you eat fewer calories than your body burns, which forces it to use stored fat for energy.
Medical Disclaimer: This guide provides educational information. It is not medical advice.
Definition
A Calorie Deficit is a state in which you consume fewer calories than your body burns in a day. When this happens, your body must pull energy from its stored reserves (primarily body fat) to make up the difference, resulting in weight loss over time.
Why It Matters
A calorie deficit is the fundamental biological requirement for weight loss. No matter what diet you follow—keto, paleo, vegan, or intermittent fasting—if you lose weight, it is exclusively because that diet forced you into a calorie deficit.
To calculate your required deficit, you first need to know your Total Daily Energy Expenditure (TDEE).
Practical Example
The Math of Weight Loss
One pound of body fat contains roughly 3,500 calories. To lose one pound of fat per week, you need a weekly deficit of 3,500 calories.
- 3,500 calories ÷ 7 days = 500 calories per day
If your TDEE is 2,500 calories a day, eating 2,000 calories a day creates a 500-calorie daily deficit. Over one week, this will theoretically result in one pound of fat loss.
If you want to calculate exactly how many calories you should be eating to hit your weight loss goals safely, use our Calorie Calculator.
Frequently Asked Questions
How large should my deficit be?
A safe and sustainable deficit is typically 300 to 500 calories below your TDEE, which results in about 0.5 to 1 pound of weight loss per week.
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