Looking to get back to comfortable

I have been steadily gaining weight for the past 4 years. I have shot up from a size 4/6 to a size 10/12. I used to be a lot more active and when I started spending more time at home I didn't change my eating patterns. I am 25, 5'7", and I waffle between 160-165 lbs. None of my clothes fit anymore. I started eating more fatty foods than I used to as well. A typical lunch from a few years ago was a tomato sandwich and soup, now its more like a cheeseburger and fries. That puts me right on the line of overweight and I want to nip these habits now before I find myself in a much more difficult predicament. My goal is to get back down to a size 6.