Calorie Deficit Explained: How Big a Deficit to Lose 1 lb a Week

A calorie deficit means eating fewer calories than your body burns, so it taps stored fat for the difference. To lose about 1 pound of fat a week, you need a deficit of roughly 500 calories per day — because a pound of body fat holds about 3,500 calories, and 500 × 7 days = 3,500. Here's how to set yours without overthinking it.

How does a calorie deficit actually work?

Your body burns a certain number of calories every day just existing, moving, and digesting food — that's your TDEE (Total Daily Energy Expenditure). Eat below that number and your body makes up the shortfall by burning stored energy, mostly fat. Eat above it and you store the surplus. That's the entire mechanism.

So fat loss isn't about one "bad" food. It's about your total intake sitting reliably under your total burn, day after day.

How big a deficit do I need to lose 1 pound a week?

The classic math: one pound of fat ≈ 3,500 calories.

• 0.5 lb/week: ~250-calorie daily deficit
• 1 lb/week: ~500-calorie daily deficit
• 2 lb/week: ~1,000-calorie daily deficit (aggressive — usually too much)

A 1 lb/week pace from a 500-calorie deficit is the sweet spot for most people: fast enough to see weekly progress, gentle enough to protect your energy, training, and muscle.

A realistic example

Say your TDEE is 2,200 calories a day. A 500-calorie deficit means eating about 1,700 calories a day. Over a week that's a 3,500-calorie shortfall — roughly one pound of fat.

The 3,500-calorie rule is a useful approximation, not a law of physics. Real-world weight bounces around with water, sodium, and food in your gut, so judge progress over 2-3 weeks, not day to day.

How do I find my deficit number?

1. Estimate your TDEE (maintenance calories) from your stats and activity level.
2. Subtract about 500 for a 1 lb/week target — or keep your deficit around 20% below maintenance, whichever is gentler.
3. Keep protein high (about 2g per kg of bodyweight) so the weight you lose is fat, not muscle.

For the full breakdown of macros, see our guide on how to calculate your macros for fat loss. For more free tools across nutrition, fitness, and life, see the health tools hub.

A quick caveat

Calorie targets are estimates, not medical advice. Going much below your maintenance — or under roughly 1,200 calories a day for most adults — can backfire and should be done only with professional guidance. If you have a medical condition or are pregnant, talk to a doctor or dietitian first.

Get your number in seconds

You don't need a spreadsheet. Our free macro calculator finds your TDEE, applies your deficit, and hands you a calorie target plus a protein/carb/fat split — no signup, about ten seconds.