What Is a Calorie Deficit? (In Plain English)

The simple version

Your body uses energy every day to keep you alive, move you around and digest food. That energy is measured in calories.

Eat fewer calories than you use, and your body makes up the gap from its stores, mostly fat. That gap is a calorie deficit.

Think of it like a fuel tank

• Food is fuel going in.
• Living and moving burns fuel.
• Burn more than you put in and your reserve tank (body fat) goes down.

How big should it be?

Small. Aim to lose about 0.5 to 1% of your body weight a week. For a 90kg man that’s roughly half a kilo to a bit under a kilo. Bigger gaps leave you tired, hungry and cranky with the kids, and eat into your muscle.

How do I make one?

• Slightly smaller portions
• Fewer drinks and snacks you don’t really care about
• More walking
• Protein and veg at every meal so you stay full

How do I know it’s working?

Weigh yourself a few mornings a week, same time, after the toilet. Look at the weekly average. Slowly going down? You’re in a deficit. No change in two or three weeks? Make one small tweak.

FAQ

Do I need to starve?

No. A small deficit should feel like eating a bit less, not starving.

Can I still eat foods I like?

Yes. No food is banned. It’s the total over the day and week that counts.

Why did my weight go up when I ate less?

Daily weight jumps around with water, salt and food in your gut. Watch the weekly trend.

This article is general information only. Check with your GP before changing your diet or training if you have a medical condition.