Most fat burners have high amounts of caffeine, which helps aid in the fat burning process. The jitteryness is based on your tolerance for stims. I'm currently taking Oxyelite Pro and I've seen amazing results without getting any jitters, but i have a fairly high tolerance to stims. If you want to try a fat burner with less stims than OEP USPLabds also puts out Recreate which is also good, but i haven't tried it.
I'd suggest maybe trying OEP and see how you like it. Just ease yourself onto it and make sure to take it with food so that you can avoid the jitteryness as much as possible. Good luck!
For the first week or so I was on OP I felt like a crack addict haha.
Constantly tweaking out and my hands would shake.
( drank a ton of water as well )
Something else that was strange... My dick got pretty small ( like if it was cold out ) - still functioned fine and would go back to normal when the gf wanted to play around.. But when just walking around and what not it was like it was constantly cold or something.
Thankfully that only happened the first week and once my body started to adapt to the caffeine I stopped tweaking out , hands didn't shake as much and my dick stopped shriveling up.
Not sure why it happened in the first place... But it did lol