imho, losing weight is 80% diet 20% excercise and pure will, you can't cheat, at all, not one cheat day or your glycogen levels will spike and you'll want to cram sugar and fats for days after. Maybe that's just my opinion, but the thing is, after you lose the weight the hardest part is keeping it off. If you think you can just drop 40 lbs in a few months, then start eating like you did before your diet, it's going to bounce back real quick. Alot of people don't think about that, they just wanna see it come off quick.
The best way is to give it all up, completely change your lifestyle of eating forever, don't look at it like a short term diet, look at it like you're sober now and don't want to relapse. When I started eating right it took me about a month and then I would love the taste of healthy foods that I hated prior to eating correctly. Stuff like steamed broccolli, salad with super light dressing, plain chicken/tuna w no ketchup/hot sauce/mayo. Then after about 6 months of eating so good, I had this one day where I was fiending some pizza and wings, BAM instantly after eating only a few slices and 6 wings I was feeling sick as hell, all bloated, shitting for hours, lethargic and sweating. It was nuts