My son in law has done what you did and he’s lost about 70 lbs. Meanwhile, I have a friend pushing this Octavian diet???? She loses some 5+ pounds per week!!! Seems a little high to me as you’d think slower is better.
Congrats to your sil!
I never heard of that diet myself.
I’m a believer in losing weight slowly in the beginning & gently adding walking into things soon as strength returns to make it happen.