Hi newbie,
Regain is not one simple answer for people that experience it. Have compassion. Learn from the stories and experiences of everyone here.
For people reading this thread and are new or researching surgery. Regain does not happen to all of us. follow this link to positive outcomes for a balanced perspective of weight loss surgery.
https://www.bariatricpal.com/topic/423992-what-you-had-no-surgery-complications/?tab=comments#comment-4758950
Have you had your pre op class yet? Surgery is only a tool. You must do the work. This is not the easy way out. Surgery restriction alone will not keep you successful long term.