Q. I've heard a lot about people losing weight with the 'Subway diet.' What exactly is the scientific and medical principle behind why this works?

Effective dieting is less about caloric restriction and more about the quality of the 'fuel' you provide your body. From a modern nutritional perspective, the Subway diet's success lies in its high dietary fiber content, which promotes satiety and slows nutrient absorption. This prevents the 'glucose spikes' that trigger excessive insulin secretion, eventually transitioning the body into a state that resists fat storage. From the perspective of Traditional Korean Medicine (TKM), we view this as a process of normalizing the 'Biwi' (Spleen and Stomach) functions. Patients who struggle with weight gain despite low energy levels often suffer from 'Biheo' (Spleen Deficiency). In this state, the body fails to convert food into vital energy, instead producing 'Dameum' (phlegm-fluid) or 'Eohyeol' (blood stasis), which are essentially metabolic wastes that lead to obesity and stagnation. A customized Subway meal using unprocessed ingredients helps prevent the accumulation of such waste and facilitates the smooth circulation of Qi and Blood (Gi-hyeol). However, a word of caution for those with a 'cold' constitution or naturally weak digestion: excessive consumption of raw, cold vegetables can further dampen the Spleen’s energy. For these individuals, it is medically advisable to toast the bread or opt for warm toppings to protect the digestive fire. Tailoring the meal to your specific constitution is the most vital step in achieving sustainable health.