there are these tablets for fasting called ramadan fasting tablets
they're for muslims who fast during their holy month and use them not to feel thirsty or hungry and it gives a energy boost too
but im wondering if its good for diets?
and does it work?

Hmm....it gives you an energy boost and makes you forget that you're hungry and thirsty? Where I come from, that's called Speed and is illegal.

In all seriousness though, no, it's not good for diets, and it doesn't work long term. You might lose weight at first, but you'll a) damage your health, and b) as soon as you come off the pills, you'll pile the pounds back on, probably more than you had to start with.

The only thing that really works is eating healthy and exercising. If you stick with that, you won't need any pills whatsoever.