The regimen she was on would be extremely unhealthy regardless of how long she had the fat. She actually seems to be just naturally a larger girl, so realistically she was never going to be as thin as they show her (not healthily anyway).
Like, if she weighed about 200 lbs before, and dropped down to even just 160, that would still be 10 lbs per week. Doctors don't tend to recommend more than 1-1.5 lbs of weight loss per week, and actively discourage more than 2. Even with rigorous exercise, she either deprived herself to the point her body would go into starvation mode, she worked out to the point of risking muscular damage, or both.
Honestly, I had lost a similar amount of weight when I did a year of ROTC training, but that was about 20 lbs lost while working out 4 days a week at minimum, and it took about 3 months (;; ̄▽ ̄)
This is so stupid I'm laughing my ass off in class
Also losing that much weight in just a month seems a bit unhealthy