The military gets all kinds of people from every corner of the country, they all go to boot camp and they all lose weight. Why? Because you eat 3x's per day as fast as you can which doesn't amount to a heck of a lot of calories. Then you're running around playing cowboys and indians the rest of the day burning up a ton of calories. Gaining or losing weight is determined by your total calorie intake for a 24hr period. If you still don't believe this I'd suggest you go down to your local Armed Forces recruiting office and join up!
If you're looking for the best weight loss diet, start by eating a certain amount of calories per day. A good rule of thumb for women is 1200-1500 calories and for men 1800-2200 calories per day. For the first week I suggest weighing and measuring every single thing that you consume and keep a food log. If you add creamer to your coffee, measure it. If you make a PB&J sandwich, measure each ingredient. If you have a chicken breast, weigh it. It's the only way to get the precise amount of food that you're eating. You'd be shocked on how much all the little things add up.
Remember, people lose weight in an overall manner and not in any particular area. Where you lose weight is determined by genetics. No matter how many sit ups you do, you'll never reduce the fat in your stomach unless you eat less and move more.