The old adage that 'baby fat eventually turns into height' is often medically misleading. In clinical practice, childhood obesity is typically calculated by comparing a child's BMI to the growth percentiles of their peers. When a child is classified as obese, their body undergoes 'hyperplastic obesity,' where the actual number of fat cells increases. Unlike adults who mainly experience an increase in cell size, children develop a higher cell count that persists for life. Even if weight is lost later, these cells only shrink in size, constantly awaiting an opportunity to expand, which is why the yo-yo effect is so prevalent in those who were overweight as children. From the perspective of Traditional Korean Medicine (TKM), this phenomenon is linked to the cycle of Spleen Deficiency (脾虛) and the accumulation of Phlegm-Fluid (痰飮). When the Spleen—the organ responsible for transformation and transportation—is weak, unprocessed nutrients turn into pathological metabolic waste called Phlegm-Fluid. Accumulated from a young age, this Phlegm-Fluid obstructs the circulation of Qi and Blood, creating a constitution where fat is not easily burned. Over time, it can become as stubborn as Blood Stasis (瘀血), interfering with the overall metabolic rate. Monitoring a child's obesity level is essentially checking how their 'metabolic engine' is being calibrated for life. If the fat cell count has already increased, it requires a more delicate and precise constitutional improvement (體質改善) to reset the body’s metabolic balance.