What is this disease about?

I believe she means dehydration. It is not a disease, but a

symptom of not having enough water in your body.

Some people do get thirsty when the lack water, but others

get used to not drinking. This can harm your body by

slowing your metabolism down, by not having enough to

help flush your kidneys out and people can develop kidney

stones because of it. Other things is that your body needs

water and fluids to function well.

Coffee, tea, soda, and other cafeine drinks act more like

diuretics and should not be counted as taking fluid in.

Over consuming fluids is just as bad as not drinking enough.

It can also cause problems. Your skin will do much better if

you are hydrated properly. It plumps the skin up and gives

you a more healthy look. When dehydrated, when you pull

the skin up, it rebounds slower back to its original shape.

http://en.wikipedia.org/wiki/Dehydration

Hope this information helps...best wishes