Hi im dr.hema physiotherapist. For safety s sake, check with your doctor if you have any concerns to rule out thyroid imbalance, pcod which are most common causes for weight gain and irregular periods. In mean time you can start with workouts and diet to reduce weight.even 10 to 20 % reduction in weight helps to regain your regular periods, whatever the cause. 1.A proper balanced diet- Avoiding unhealthy food.slow weight reduction always fits to any one.crashing diet will end up in health issues. Eat lot of fruits and vegetables, this will not only reduce hunger but also add to the bulk of the food.skimmed dairy products, take fresh salad after lunch and dinner like cucumber, tomatoes with curd. Take green tea twice daily. Reduce salt intake.drink plenty of water. Avoid high calorie food like fries, pizza, sweets and others. 2.be active, reduce time sitting in front of tv or computer........ 3.start with walking, , Swimming 3 to 4 times a week.reaching nearby shops by walk. 4.you can start with abdominal crunches and hip exercises. 5.check your weight weekly. Overweight may put you in other health issues, even mild change in lifestyle helps you for good health. Hope the information is useful.do reply in doubt.im happy to guide you.