According to testimonials from people who used the drugs and stop, they rapidly gain weight back. However, if they stick to a healthy lifestyles, they will regain minimally.
Charles Barkley for example disclosed that he regained about 35 lbs after loosing way over 100.
One thing that he mentioned was his doctor declaring, do you know fat old people?. So rude.
In fact, when you get older, you naturally lose weight.
I hate listening to people bitc%ing about being too skinny. Girl, come stay with me for a week and watch yourself gain effortlessly.
A friend of mine was wheelchair bound for a short time, and managed to lose weight. Yes, she has a fast metabolism but unlike me who turn to food in time of stress, she stops eating completely.
In your friends case, it sounds like bragging and competitive. Typical mean girls crap.
Oprah stated that she felt healthier and could run faster. For her, it was mainly about health and performance

If she likes it I love it for her.
As far as side effects from the drugs, thyroid and other metabolic issues including pancreatic disease. So one needs to be monitored closely.