Weight gain is a normal symptom of premenstrual syndrome, or PMS. This symptom of PMS is due to water retention.
Water retention occurs when your body retains more water than it should. This can cause a slight increase in weight as well as bloating.
According to the Mayo Clinic, it is unclear why women experience symptoms of PMS, or why water retention occurs directly before a woman's period. It is suggested that the hormonal changes in the body play a large part.
Symptoms of water retention include a slight increase in weight, bloating and feeling heavier.
According to the Mayo Clinic website, lowering salt intake, being physically active and eating healthier can help reduce water retention before a woman's period.
Water retention is not always preventable, but it is treatable. There are many over-the-counter medications available, such as Midol or Pamprin, that relieve water retention and other symptoms of PMS.