Calories are the energy source that powers every function in your body, from breathing and digestion to movement and exercise. Your body burns calories through three main processes: Basal Metabolic Rate (BMR), physical activity, and the thermic effect of food. The number of calories you should burn daily depends on factors such as age, gender, body composition, activity level, and health goals. For weight loss, creating a moderate calorie deficit of 300–500 calories per day is generally considered a sustainable approach. Weight maintenance requires balancing calorie intake with calorie expenditure, while muscle gain often involves strength training, adequate protein intake, and a slight calorie surplus. Building muscle can also increase calorie burn over time. Healthy habits such as regular exercise, strength training, proper sleep, hydration, and protein-rich meals can support metabolism and overall wellness. Consistency and balance are more effective for long-term health than extreme dieting or excessive exercise.