Oh, wow, that is both an amazement and a sadness about your dsisil, Kathryn. She sounds like an all-or-nothing personality, for sure. Losing so much so fast would take the kind of toll on the body that would happen if you faced some terrible famine. Yes, I can imagine hormones would be off-kilter, and I hope she is eating some carbs - she can get into real health trouble without any.
I will admit to you that I've heard the word "shred" but had to look it up to be sure of meaning. I found everything from Linux to political discussion and had to plug in "30-day" to get fitness results. I now see that the phrase may have actually been coined by Jillian and that she's done a few videos about it and there is a "sisterhood" and there are "shredheads". Who knew! I used to be well-versed in what was out there in video workouts and subscribed to Collage video's little magazine back in the day. When I settled in to T-Tapp I kind of dropped out of that loop. Your sister's experience sounds much more healthy and if it means she is leaving a cane behind, that is fantastic. I hope they can find a middle ground and reconnect.
I think the BL producers wanted to have the "good trainer, bad trainer" idea in viewers heads there for a while, to spark interest in the show. Bob would be so sensible and happy, and then Jillian would come in like gang-busters and shock everyone with a lot of wide-eyed screaming. That was when they started showing the people running outside and vomiting, too. That may not have been her real persona - who knows. I haven't watched in a few seasons, but this video with Bob reminds me of the earlier days of the show, when Bob and Kim were smiling and bringing everyone along together - I don't think I would enjoy a Jillian-dominated video experience!