Saw a joke: How do you feel about the World Health Organization defining "kidney deficiency" as a mental disorder? (Not true) It reminded me of how my feet have always been cold since I was a kid, and I always assumed it was "cold constitution." So how does modern medicine explain this? Turns out the answer is simple and interesting, and it's similar to the logic behind "cold uterus": GPT says: The body needs to protect vital organs like the heart, brain, and lungs—they must stay warm. So the body automatically does one thing: reduces blood flow to the feet and hands, pulling heat toward the body's core. As soon as the body feels a bit cold or senses the environment is unstable, it immediately turns down the "heating" for the feet. Why do some people’s feet get their "heating" turned off so easily? Mainly because some people’s bodies are "highly alert" (their sympathetic nervous system is more sensitive). Even a little cold triggers a big reaction, and the body quickly enters "power-saving mode," causing blood vessels in the feet to constrict first—making hands and feet very prone to getting cold. (For women, "cold uterus" is mainly due to the nerves in the lower abdomen being more sensitive.) People who exercise more are better at "keeping heat in the core," because that’s the survival mode for athletes. Damp cold makes the body lose heat faster than dry cold. Humid air causes heat to escape from the body faster, just like wet clothes in winter feel colder than dry clothes. Moist air steals heat from the skin. How to fix it? The most important thing is to remember to wear socks indoors too.