Based on her before pic, I'd say her transformation was possible without AS. Like the others said, she's not that muscular, just very lean, and being very lean adds to the illusion of greater muscularity. Also, if you just saw her walking down the street, she would not look as defined as she looks in her after pics. For one thing, they've got her skin very dark and oiled. That and good photographic lighting enhances her cuts to the max.
She's done a great job to be sure, but she really wasn't THAT bad to start with. Her before pic is made to look worse by her slump-shouldered posture, sad expression and no makeup. It appears she's possibly pooching her belly out to add to the effect. If you look at her contours though, you can see a nipped-in waist, no saddlebags on her thighs, etc. just an overall layer of bodyfat smoothing her out. The pale skin and bad lighting makes her look fatter than she really is.
I wouldn't focus on a "12 week transformation". It could backfire. I'd like to see a picture of her a year from now to see if she's maintained. Given a realistic timeframe, proper diet and exercise though, I do believe such a look is possible (and maintainable) without AS.