You must have noticed that some of your friends eat a lot of sugar-based foods, fried foods, or cold drinks. Yet, they manage to have a flat stomach, the reason being they have a very high metabolic rate. If your metabolism is not good, you may have a bloated stomach. Thyroid conditions, diabetes, and other medical conditions can be the reasons for slow metabolism.
We just don't feel full by liquid calories in quite the same way as we do real food. Drinking a juice or caramel coffee drink just isn't as satisfying as eating a bowl of veggie- and protein-packed stir-fry. So monitor your intake of juice, soda, sweetened coffee and tea, and alcoholic beverages. If you consume each of those beverages during the day, you'll have taken in at least 800 extra calories by nighttime — and you'll still be hungry. (Incidentally, alcohol may suppress the metabolism of fat, making it tougher for you to burn those calories.)
Here's something else most people probably don't know: Fidgeting is good for you. It's considered a nonexercise physical activity, and it's an important way to burn energy. You get more health benefits if, in addition to exercising, you are a more fidgety, more active person the rest of the day. This means gesturing while you're talking, tapping your foot, just moving around.