I'll tell you what everyone says," abs aren't made in the gym. They're made in the kitchen." So, the simplest rule of all is EAT HEALTHY! And eat right. Yoga won't help you lose weight, however, it'll help you stay fit. You can start running, start body weight training, swimming, cycling, a lot more! Make a few changes and you'll lose weight eventually. PS in the first month you'll lose a lot and subsequently it'll reduce. So, don't panic. Once the water weight is gone, fat starts burning.