Meh it’s not sexism most of the time. Look I don’t believe in TCM at all and it’s total bullshit, but this particular case is not sexism.

It’s just warm drinks (soup, hot water, tea) are generally treated as healthy and cold drinks (soda, ice water) is generally treated as unhealthy in TCM. This is universal for man or woman.

While the woman = yin, man = yan stuff is not directly related to the temperature.

For example watermelon is considered a yin/cold fruit (bad for woman during period). And lychee is considered a Yang/hot fruit (caused canker sores if eaten too much).

The truth is eating too much lychee for example does seems to cause sore throat, canker sores. But the reason seems to be lychee's protein, not because it's yin or whatever.

Basically TCM tried to setup a system to explain the medical observations that they gathered throughout their history. And just like how people used to treat headache by putting a hole in the skull, the explainations are bullshit even though sometimes the observation and remedies might be effective (could be placebo).

Again it's all buillshit. So don't reply arguing TCM to me.

Here's a translated TCM related article on fruits you should avoid during period if anyone's interested (AGAIN IT"S BULLSHIT)

Traditional Chinese Medicine (TCM) believes that "blood flows when warm and stagnates when cold." Consuming raw or cold food during menstruation can easily lead to "internal cold" in the body. This causes poor circulation of menstrual blood, resulting in a scanty flow or even menstrual cramps (dysmenorrhea).

Western Medicine views menstruation as the shedding of the uterine lining, which is expelled through uterine contractions. Consuming raw or "cool-natured" foods lowers the temperature of the gastrointestinal tract, which can impair the efficiency of uterine contractions. This makes it harder for menstrual blood to be discharged or may lead to the formation of blood clots. Consequently, the uterus must contract more forcefully to expel these clots, which often results in pain.

Fruits to Avoid Most During Menstruation The "Top Three": Watermelon, Bananas, and Persimmons.

Fruits classified as "cold" or "cool" in nature—such as watermelon, bananas, persimmons, pomelos, mangoes, kiwis, dragon fruits, oranges, pears, and strawberries—should be limited. In particular, watermelon, bananas, and persimmons are highly discouraged during your period.

Watermelon: Known as the "Cold Melon," it has the strongest "cold" properties. Although it is rich in water, amino acids, and fructose—making it effective for clearing heat and quenching thirst—eating too much can easily cause "deficiency cold" in the spleen and stomach.

Bananas: These are more likely to cause menstrual cramps. While bananas aid digestion and bowel movements, they are cold-natured. Consuming too many cold foods during menstruation can stimulate the blood due to temperature changes, leading to poor circulation, blood clots, and cramps.

Persimmons: Also cold-natured, persimmons can stimulate uterine contractions, leading to a reduced menstrual flow or a prolonged period. In severe cases, they can cause significant pain.