I've been sort of following The Swan on Fox TV, and I'm struck by the fact that a huge amount of change takes place between the last "pre-unveiling" scenes and the actual grand entrance.
Most of the contestants seem to have deep-rooted psychological problems, enough so that I tend to wonder how much of their appearance (within their control) is attributable to their mental state. Part of the transformation does involve therapy, and if you subscribe to the Dr. Phil school of thought, three months is plenty if you're willing to face your issues.
When we last see the contestants prior to the end of the show, they are still struggling with adjusting to their new diets and workout routines as well as sometimes not following the rather simple instructions for optimal surgical recovery. Some of this really reflects on what their lives must be like, subconsciously shooting themselves in the foot with whatever they try, causing themselves to fail.
The point being, that when they appear at the end of The Swan, they seem to have gotten a handle on most of that. They are (apparently) poised and confident.
That's quite a leap to make between commercial breaks. :-)