Unexplained or unexpected weight gain in women can occur due to abnormal growths, constipation, pregnancy or fluid retention, explains Healthline. Unexplained weight gain can also occur when hormones in the body change as a result of menopause or menstruation, certain medications and diseases such as hypothyroidism.
Medical conditions that can cause unexplained weight gain include Cushing's syndrome and increased production of stress hormones, according to Healthline. Medications such as birth control pills, antidepressants, antipsychotic medications and corticosteroids can also cause unintentional weight gain in women.
Women who do not get ample sleep, experience chronic stress or take medication for blood pressure, heartburn and diabetes may be at risk for unexplained weight gain, explains WebMD. Polycystic ovary syndrome, which causes small cysts to develop on the ovaries, can also cause unexplained weight gain. People who quit smoking may be more at risk for gaining weight as well.
Symptoms of unexplained weight gain include visible swelling in areas of the body such as the abdomen; swollen arms, legs, feet and hands; bloating; constipation; abdominal pain; and flatulence, according to Healthline. Unexplained weight gain occurs when women continue to put on weight even when they have not increased their food and liquid consumption.