Rapid weight loss problems: ① mainly muscle and water loss (not fat), ② rebound rate over 70%, ③ metabolism slowdown (yo-yo effect), ④ nutritional deficiencies (hair loss, fatigue, gallstones), ⑤ psychological burden. Healthy weight loss: ① 0.5–1kg/week (2–4kg/month), ② muscle preservation focus, ③ sustainable lifestyle changes, ④ rebound rate under 30%. Korean medicine targets healthy gradual loss with metabolic improvement, not extreme calorie restriction.