I started taking Effexor again in February after having been off it for 3-1/2 years. I'm now taking it IR 125mg 2 times a day (@ in the morning and around 3 pm) rather than 225mg XR. I have noticed my experience to be far different from when I took it four years ago. On the positive side, the side effects are a bit less--I can take it on an empty stomach without feeling dizzy or queasy, and it doesn't interfere with my sleep as much. However, I am not feeling the same benefit to my mood that it provided then. I originally blamed the lesser effect on taking the XR formulation, but now that I've switched back to the IR, it's same old, same old. The depression is getting so bad that it interferes with me being able to study and focus, and last Saturday, I just sat around my house and cried. Could I be developing a tolerance to the medication?
As for weight gain/weight loss, YMMV. I never gained weight with the SSRIs (I've tried 3 different ones), Effexor or Wellbutrin (actually lost weight on Zoloft), but gained 15 pounds in 3 months on Remeron. Prozac made my anxiety much worse. Good luck!