📝 Detailed Answer
From a medical perspective, caffeine acts as a trigger for 'Thermogenesis,' stimulating the sympathetic nervous system so that the body consumes energy even at rest, similar to being in a state of exercise. During this process, fatty acids released from fat cells circulate in the bloodstream and are readily burned as fuel with even light physical activity.
In Traditional Korean Medicine, coffee is understood to have properties that lift 'Qi (氣)' upward and dry out 'Jin-ye (津液, essential body fluids).' While a moderate amount can help discharge 'Dam-eum (痰飮, metabolic waste or Phlegm-rheum),' excessive intake inevitably causes issues. This is especially true for those with a 'Spleen Deficiency (脾虛)' constitution—people who generally lack energy or have weak digestive systems. While a cup of coffee might temporarily suppress hunger, it leaves the internal system 'hollow.' Because you are essentially squeezing out energy by force, the body may enter a survival mode and hold onto fat more tightly to compensate.
Furthermore, if internal 'Heat (熱)' accumulates to the point of causing insomnia or heart palpitations, your metabolic efficiency will actually plummet. Before using coffee as a weight-loss tool, it is vital to prioritize hydration and digestive health. The shortcut to sustainable weight loss without the yo-yo effect is creating a body that circulates well, rather than one that is simply forced to burn out.