"Doctor, I think I drink enough water, so why am I always tired and my skin so dry?" I hear this question quite often. In modern medicine, the body fluid deficiency described in Donguibogam can be understood through the concept of chronic dehydration. Simply not feeling thirsty does not necessarily mean your body has enough fluid. Water constitutes 60 to 70 percent of our body, and even a slight deficit of 1 to 2 percent can trigger minute yet significant changes, much like how the flow weakens when a faucet is turned down just slightly.
At the cellular level, chronic dehydration impairs the permeability of the cell membrane and lowers the energy production efficiency of the mitochondria within cells. Mitochondria function as our cellular power plants, and when water is insufficient, these power plants cannot operate properly, leaving the body fatigued. It also directly affects brain function, as the brain is composed of 80 percent water. A lack of fluid reduces cerebral blood flow and decreases the efficiency of neurotransmitters, potentially causing impaired concentration, memory impairment, and even anxiety or headaches. It is also a primary contributor to brain fog, where the mind feels clouded and dull.
Skin health is affected in the same way. The skin is the largest organ in our body, and the collagen and elastin fibers in the dermis maintain their elasticity when adequately hydrated. Chronic dehydration lowers the water content of skin cells, weakening skin barrier function, deepening fine lines, and leaving the skin dry and rough. Dry skin is more vulnerable to external irritants, which can worsen atopy or allergic responses. Furthermore, it influences the digestive organs. When intestinal moisture is lacking, stool hardens and bowel motility slows, leading to chronic constipation. Gut health is closely connected to immunity, meaning a disrupted intestinal environment can affect systemic immune function.
The endocrine system experiences subtle disruptions as well, because chronic dehydration can raise levels of the stress hormone cortisol. Chronically elevated cortisol can lead to various problems, including decreased immunity, blood glucose dysregulation, and sleep disorders. It also places a burden on the kidneys, lowering waste excretion efficiency and increasing the risk of urolithiasis. In this manner, chronic dehydration acts as a silent disruptor that quietly exerts complex negative effects on whole-body health. Drinking sufficient water is more than quenching thirst; it is the most fundamental step to keeping every bodily system running smoothly.
