At first it was by eating low fat foods and exercise. I cut out all baked goods, chips, fried foods, soda, coffee ( hardest to quit lol) etc. I started walking 10 min a day at first. It slowly morphed into a low fat, high fiber vegan diet and I was walking 45-60 min a day.
I am not sure I will go back to vegan or even all vegetarian again but I do think high fiber is a key for me.