Do some antidepressants caused extreme weight gain?

Most do, about 25%: Most antidepressants have some risk (about 25% chance) to gain about 10 pounds. How to manage? Monitor your weight and report to psychiatrist. If marked cravings, consider a switch of antidepressant. One group from mit/harvard suggested that a small dose of "carbs" can decrease the cravings due to the serotonin effect of antidepressants. Might try snacks of pretzels, popcorn, rice cracker.

Not extreme: Though many of the antidepressants can cause some weight gain, it is usually not extreme. In my experience, mirtazepine (remeron) is most likely to cause weight gain and venlafaxine (effexor) or Cymbalta (duloxetine) are least likely.