However, if salt is added to the drinking water, the salt is salty, but it belongs to the kidney, and a small amount of salt can enter the kidney meridian to nourish yin and tonify kidney (a small amount of salt is often added to the kidney meridian when taking kidney tonic drugs) (but a large amount of salt has a destructive effect on renal function, so nephritis should avoid salt). Although you drink salt water, the increase of urine is not obvious, and even perspiration is reduced, so your weight gain is more obvious. This is also the reason why eating salty things can easily cause high blood pressure.