How Many Calories Do You Actually Need Per Day?

"2,000 calories a day" is a label-printing convention, not a personal recommendation. Your real number depends on your size, age, sex, and how much you move — and calculating it takes about thirty seconds once you know the two pieces involved.

Piece 1: Your BMR

Basal Metabolic Rate is what your body burns at complete rest — keeping your heart beating, lungs breathing, brain running. It's typically 60–75% of everything you burn in a day. The Mifflin-St Jeor equation is the standard estimate:

A 40-year-old woman, 165 cm and 70 kg, has a BMR around 1,370 calories. A 30-year-old man, 180 cm and 85 kg, sits near 1,830.

Piece 2: Your Activity Multiplier

Multiply BMR by an activity factor to get your TDEE — Total Daily Energy Expenditure, the calories that maintain your current weight:

Most people overestimate this. A desk worker who hits the gym three times a week is "lightly active," not "very active" — the honest multiplier matters more than any other input.

Setting a Deficit That Sticks

The classic rule of thumb: a 500-calorie daily deficit produces about 1 lb (0.45 kg) of loss per week. It's an approximation — metabolism adapts and the rate slows over time — but it's a sound starting point. Two cautions:

• Don't slash too deep. Very low intakes are hard to sustain, cost you muscle, and backfire via rebound. A 15–25% cut below TDEE is the sustainable zone.
• Recalculate as you go. A lighter body burns fewer calories; update your numbers every 5 kg or so.

Calories Aren't Everything

For weight, energy balance dominates. For everything else — satiety, muscle retention, energy levels — composition matters: protein and fibre keep you full far longer than refined carbs at identical calories. The easiest diet to stay on is one where you're not hungry all the time.