Doctor, I always hit a wall when I'm on a diet. Why does this happen? Is it just a lack of willpower?

I have actually experienced this myself; I once tried fasting blindly and nearly fainted from dizziness. Having been through that trial and error, I can tell you that this is not a failure of will, but rather a survival strategy employed by the body. Biologically, when food intake drops suddenly, the brain perceives it as an 'emergency.' To conserve energy, it slows down the metabolic rate while simultaneously triggering 'false hunger' to induce eating. This is often why severe yo-yo effects occur after aggressive pharmaceutical weight loss treatments. In Traditional Korean Medicine, this state is referred to as 'Spleen Deficiency' (Bi-heo). When the Spleen—which governs digestion and nutrient absorption—becomes weak, nutrients are not properly distributed throughout the body. This leads to the accumulation of 'Phlegm-fluid' (Dam-eum), a type of metabolic waste, and can cause 'Blood Stasis' (Eo-hyeol), where blood circulation stagnates. This creates a vicious cycle that further slows down the metabolism. When you wonder, 'Why am I not losing weight even though I'm eating so little?', your body is actually sending out a distress signal. The answer is not simply eating less, but first boosting your diminished metabolic function. Let's work together to carefully assess the current state of your body.