There's this guy who went on what he called the Cookie Diet that my ex once told me about because one of his classes was about nutrition or something and his teacher did a lesson on this.
He loved sweets, mostly cookies, but he wanted to lose weight and be healthy. So for his diet, every single morning he'd have a plate of cookies for breakfast. Then the rest of the day, it was NO COOKIES. No sweets. So he went on a diet, sort of, and still got to have his cookies
Anyway my best advice is just to exercise. Even if you don't change anything with your current diet, at least getting exercise will help. It can even be simple things, like sit ups, stretching, jumping jacks, running in place, push ups, going for a walk. You don't have to go to a gym or invest in weight lifts of sorts in order to get into shape. Cavemen didn't have gyms or weights. The best (and cheapest) form of exercise is naturally.