Energy bars/diet drinks?!

Energy bars/diet drinks?

sorry for the ammount of questions i have a few lol
so ill do two in one...they kinda relate

alright so energey bars (the ones you see in the same section as diet pills and such)
are they bad for you? and do they actually give you alot of energy?

and also

i know diet drinks are bad for you but i dont know how? like what do they do to you thats not good?

thanks :]

2 weeks ago
diet drinks such as diet coke,pepsi, iced tea, ect

I have eaten Powerbars--they don't taste the greatest, but you definitely notice within an hour that you have more energy for about 2--3 hours...