How Many Calories Do You Actually Need Each Day?

A calorie is a unit of energy. The "calories" listed on food labels are kilocalories (kcal) — the amount of energy required to raise 1 kilogram of water by 1°C. Your body uses energy constantly: not just during exercise, but to breathe, maintain body temperature, power your heart, repair cells, and keep your brain running. This baseline energy consumption is called your Basal Metabolic Rate (BMR).

The most accurate commonly-used formula is the Mifflin-St Jeor equation (1990): 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. For example, a 35-year-old woman who weighs 65 kg and is 165 cm tall has a BMR of approximately 1,444 kcal/day — the minimum calories her body needs at complete rest.

Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor: Sedentary (little or no exercise) = BMR × 1.2; Lightly active (1–3 days/week) = BMR × 1.375; Moderately active (3–5 days/week) = BMR × 1.55; Very active (6–7 days/week) = BMR × 1.725; Extremely active (physical job + hard training) = BMR × 1.9.

Using the example above: if she exercises 3–4 days per week, her TDEE is approximately 1,444 × 1.55 = 2,238 kcal/day. To maintain her current weight, she should consume around 2,238 calories daily. This is the number you should use as your maintenance baseline.

To lose weight, create a calorie deficit. A deficit of 500 kcal/day generally produces approximately 0.5 kg (about 1 lb) of weight loss per week. However, eating below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision is not recommended, as it can deprive the body of essential nutrients and slow metabolism over time.

To gain weight and build muscle, aim for a modest caloric surplus of 250–500 kcal/day above TDEE, combined with a progressive strength training program. Larger surpluses lead to more fat gain alongside muscle. Gradual, controlled increases tend to produce better body composition results over the long term.

"All calories are equal" is a persistent myth. While 100 calories of sugar and 100 calories of broccoli contain the same energy, they affect hunger hormones, blood sugar, and satiety very differently. Protein is the most satiating macronutrient and has the highest thermic effect — your body burns roughly 20–30% of protein calories just by digesting it. Food quality matters alongside quantity.

Another myth is that eating before bed causes weight gain automatically. Research shows that total daily calorie balance is what determines weight change, not meal timing. Overall dietary patterns and total intake are far more important predictors of long-term weight than when you eat.