Eat less + exercise
The most reliable way to lose weight
is by eating fewer calories than your body burns
up during a day.
Look at the foods that you eat in between meals, the sweet drinks, even juices and you'll find a lot of extra calories that you probably can do without. Then try to be more active. Start walking 10 minutes a day. Increase till you're walking 30 minutes. When you're there, push for 2 miles/day.