"I could eat an entire large Pizza Hut thick crust pizza BY MYSELF and then eat another meal a few hours later, and I did this kind of thing on a regular basis. Now, for example, I can eat a pound of carrots and an apple and that is all I would need to eat that day to be full. I can't believe how much food I ate in the past."
This demonstrates that a junk food diet does not satisfy the body's need for nutrients and will keep you hungry and wanting more food, far more often: the body's own way of telling you that it is not satisfied nutritionally, which results in more obesity in general.
A nutritious and natural diet will satisfy your bodys need with the demand for less food than previously, and therefore no obesity. Voila.