The only person I have known to take it was on 300mg a day in two doses and wasn't at all overweight. Had been on it for years, expected to be on it for the foreseeable future. They also had a huge appetite and ate a lot, including hoovering up others leftovers, loads of junk snacks, sweets, pop, and takeaways at least three times a week.
They were on other medication too, perhaps that makes a difference? Or they were just lucky...