Hello, Irregular periods is caused by hormonal imbalance (like
prolactin, oestrogen, progesterone,) hypothyroidism, reproductive tract infections, PCOS, anemia,fibroids, stress etc, hypothyroidism and PCOS can also increases weight. You need to be treated for that to lose weight too, please consult gynecologist. To lose weight, limiting calories is most important along with workout. Usual diet with workout increases weight. So please decrease your overall calories in a day.