Seeing 5 kg down on the scale in one week can happen, but much of it is usually water and glycogen—not fat. When carbohydrates drop, glycogen stores shrink and water loss increases. True fat loss in such a short window is typically limited. Very aggressive dieting can cause dizziness, fatigue, muscle loss, and poor long-term adherence. If rapid loss is pursued, clinical risks should be considered. The most reliable approach is a measurable but sustainable weekly pace that protects muscle and health.