It's hard to say. Everyone's a little bit different. However, if your diet consists of mostly junk food and you don't exercise much at the moment, the weight might come off pretty quickly after you switch to a healthier lifestyle. That's by no means a sure thing, mind you. The two most important things are to (1) take it slowly, and (2) do not starve yourself. Keeping track of your calories will become important later on, but don't overwhelm yourself at the outset. If you're like me, you probably have a lifetime of bad habits you need to break, why stress out over tiny details? It takes time to right the ship. For your diet, what I did (and what I think is easier to maintain) is I slowly started to phase in cleaner food. One month I stopped drinking sodas. The next month, I started eating wheat bread instead of white bread. The month after that, I began to eat leaner meats. I never made too many changes at once. I gave my body (and my palette) time to adjust. If you're used to eating Cheetos as a snack, vegetables won't be very tasty . . . at first. But if you give it time and experiment with different types of fruits and vegetables (which are very important), you'll actually start to like them. As far as exercising goes, like travz said, don't overdo it. You spoke about walking and jogging, and I think that's a simple enough place to start. Let your body get used to more physical activity. I can tell you from experience, trying to do too much too soon fucking hurts, haha. It sounds like you have the right idea, though.