Calorie

A calorie is a unit of energy. In nutrition, we actually use kilocalories (kcal), where 1 kcal equals the energy needed to raise 1 kilogram of water by 1 degree Celsius. Each macronutrient provides a specific calorie density: protein and carbohydrates provide 4 calories per gram, fat provides 9 calories per gram, and alcohol provides 7 calories per gram.

The number of calories you need daily depends on your basal metabolic rate, activity level, age, and goals. The average adult needs roughly 2,000 to 2,500 calories per day to maintain weight, though individual needs can vary substantially.

Calorie counting remains one of the most effective approaches to weight management. A deficit of approximately 500 calories per day leads to roughly one pound of weight loss per week. However, the quality of calories matters too. Whole foods provide more satiety, micronutrients, and health benefits than processed foods with equivalent calorie counts.