To be honest, when I was younger, I also tried dieting by relying solely on a morning Americano out of sheer ambition. However, I eventually hit a wall where I felt dizzy and my concentration plummeted—a classic case of effort without the right direction. Low-calorie beverages and black coffee have clear advantages: they immediately reduce sugar intake and the caffeine temporarily boosts metabolism. However, the downsides are equally clear. Constant caffeine intake on an empty stomach irritates the gastric mucosa and, more importantly, can lead to a state of 'Spleen Deficiency' (Bi-heo, 脾虛). When the function of the Spleen weakens and digestive absorption drops, you may find yourself lacking energy and becoming more prone to weight gain due to a slowed metabolism. Specifically, for those with 'Phlegm-Fluid' (Dameum, 痰飮)—the accumulation of metabolic waste—or 'Blood Stasis' (Eo-hyeol, 瘀血)—stagnation in blood circulation—coffee alone has its limits. Even if you reduce calories on the surface, if internal metabolic debris remains, your body will inevitably feel heavy. Ultimately, the answer depends on your individual condition. It is fine to enjoy coffee, but you must first determine if your body is utilizing energy efficiently. If you suffer from chronic indigestion or fatigue, it would be far more effective to stabilize your basal metabolic rate through warm-natured teas or constitution-specific herbal prescriptions rather than relying on coffee.