What's the deal with caffeine

Morning,
I drink quite a bit of iced tea.  I know caffeine is a diuretic and can cause dehydration but can it slow weight loss if you drink enough water dehydration should not be a problem right?  Why do so many people limit the amount they drink?  Just wondering if it could be causing my weight loss to slow.

TIA 

Caffine and coffee in particular can be a stomach irritant.  My surgeon forbids it in the first month post op.  It also raises blood pressure for many which is why I limit it. 

I love my caffine, but I'm on decaf only to keep my blood pressure down.  Sometimes I'll treat myself to half caf.  I also drink a lot of iced tea daily. 

As for weight loss?  Don't know the answer but I'll be back to see if anyone else does.