A calorie deficit leads to weight loss when the number of calories consumed is less than the number of calories burned. This essentially forces the body to tap into stored fat for energy, resulting in a gradual reduction of body weight. When consistently maintained, a calorie deficit can lead to substantial fat loss over time. This process involves creating a balance through a combination of reduced caloric intake and increased physical activity. However, it is crucial to ensure that the diet remains nutrient-dense to meet the body's nutritional requirements during the weight loss journey.