Diets don't do much for a lot of people. It's all well and good to sit down and eat a lovely salad, then spend the rest of your day on our ass playing video games, but that won't do anything for you. You need to eat well and exercise often to look and feel good. Same vice versa; if you eat junk and then exercise a lot, you'll get nowhere.
It's a healthy balance. Also, spread your meals out over a day - it's a lot better than having just three meals a day. And drink lots of water - it actually stops you feeling hungry most of the time because you're just dehydrated (Pete already said, so go back and read his post if you haven't already). Planning your meals is good for you and cheaper too - I've noticed if I don't, I end up spending more money than I have to by buying a £2.50 Meal Deal from Tesco in my lunch break. Whereas you could spend £2 on a packet of ham, about £2 on some good seedy bread, another £1 on a salad bag, and you have lunch for the whole week. You're only paying 40% of what you'd usually spend on Meal Deals for the week, and you're cutting out the junk of the chocolate bar or chip packet too.
Quite frankly though, while I could do with some toning up and getting a little fitter, I think I'm okay how I am. When I get a bike, I think I'll do a lot better with losing weight as I rarely eat heavy amounts of junk. If I ride to and from work everyday, I've done easily ten miles a day on a bike if I get a little adventurous with my routes.