A calorie deficit occurs when you consume fewer calories than your body burns through daily activities and bodily functions. This means you are burning more calories than you take in from food and drink

. Calories are units of energy obtained from food, which the body uses for essential functions like breathing, blood circulation, digestion, and physical activity. When you eat fewer calories than your body needs to maintain its current weight (maintenance calories), your body compensates by using stored fat for energy, leading to weight loss over time

. You can create a calorie deficit by:

• Eating fewer calories (reducing food intake or choosing lower-calorie foods)
• Increasing physical activity (burning more calories through exercise or daily movement)
• Or a combination of both

A commonly recommended calorie deficit for weight loss is around 300–500 calories per day, but the exact amount varies depending on factors like age, gender, weight, activity level, and overall health

. In summary, a calorie deficit is the fundamental principle behind weight loss: consuming less energy than you expend forces the body to use stored fat, resulting in weight reduction