One kilogram of body fat is roughly equivalent to about 7,700 calories. So the timeline depends on your daily calorie deficit. A 500-calorie daily deficit creates about 3,500 calories per week, which roughly aligns with ~0.45 kg of fat loss in theory. However, scale weight fluctuates due to water, glycogen, and gut content. Fast weight loss is not always fat loss. The healthiest approach is to aim for a sustainable rate while preserving muscle, and judge progress by weekly trends rather than daily numbers.