when someone says something doesn't work, is it condescending to ask them what exactly they did?
People tend to not want advice when they're not seeking it, and when someone wants to dissect every detail of what they've done that hasn't worked, when they mentioned it merely as an anecdote, it tends to be perceived as condescending.
About advise part, I am not looking to offer him any advise I am simply defending the method and ideas, so that other people can find success with it similar to what I've done for me and for many others.
How much weight did you lose, and how long have you kept it off?
Giving up the very difficult route of changing lifestyle for the easier alternative of taking drugs for weight loss comes with both biological and social consequences.
The people talking about that shouldn't be bullied to feel ashamed of not taking or recommending taking drugs.