You can take vitamins for a metabolism boost. Try to find a calorie level that is right for you, and stick to it. If you are consistent with your calorie intake, and you count calories, you will not gain weight. If you overeat you can try to cut back a little bit and you should be able to avoid weight gain. Try some exercise, it is very easy to lose weight with exercise.

drinking water
exercising
eating 5 to 6 times a day. dont be confused it's like eating the regular 3 meals and 2 healthy snacks in between to keep you from eating something bad.
dont eat after dinner.
keep healthy foods in your house and not unhealthy snacks.
make sure your getting as much fiber as you should.
if you not you can buy OTC fiber product. as they say what goes in, must come out.