First off try to avoid Supplements they can have side effects or be unhealthy.
The best way is to eat healthy and exercise. But if you you don't have time for that you can always take cinnamon pills. They are suppose to help raise you metabolism. Or you can drink a big glass of water before every meal.
For caffeine I would say coffee or tea.
Also, there are lots of very low cal snacks that are under 50 cal like peppers, tomatoes, cucumber, carrots and other fruits and veggies.
This is my first time answering on ask so hope it helped :)