Some of the diet pills state to be metabolism booster; that mean that if you usually consume 2000 calories during the day with a metabolism booster you burn more, maybe 2200.
This way you can:
1- eat more without the fear to get fat
2- get slim as you eat the usual meals
How many calories do I need to eat in a day? Well that depends on your age, sex, weight and fat percentage. As you get older you need less and less calories everyday; you have to think to give up eating the two cheeseburgers you were eating as a teenager.
Every ten years you burn something like 5% of calories less every day; you can improve it with a metabolism booster.
Things get worse as you think that ever as you lose muscle and gain fat you need less calories; something like 6 calories less for every pound (or 12 calories for every kilogram).
The first step you can do to raise your metabolism is to get stronger; you should not overdo, just try to move more.
If you usually move by car try to park farther to walk a bit more.
If you use public transports try to get off one stop earlier and walk.
If you already walk to move around try to get faster.
The second step is to eat less but more often, this keeps your metabolism at the same level and raise your energy.
When you drop down your fuel your body adapt and lower your metabolism to keep energy; you feel weak and probably nervous because you are hungry.
Eat something every three or four hours to avoid this; this way you are prepared with something healthy to consume instead to bite your nails or swallow something from the candy machine.
This is a list of pills that is declared metabolism booster. But check the other effects to be thorough.
Sacha Inchi/Plukenetia volubilis
I have to remember that these pills should be taken under medical supervision as the side effects or the overdose can be dangerous for you.
The last three on the list are natural supplements and can be found as food such as wakame and hijiki for the Fucoxanthin, Inca peanuts for the Sacha Inchi and red meat for the L-arginine; these are foods known to have a metabolism booster.
Last information about the metabolism booster is that after a while your body will adapt to the supplements and the effect will be minimized; try to stop taking them after four/six weeks for at least a week or two to gain again the bonus of these pills.