I'll just add my two cents about Bonnie. Please note that I absolutely do not claim to know what I am about to suggest, or indeed that I have seen anything on the show that suggests it. However, I do know that reality shows notoriously edit people and events to the point that they can be reinterpreted and in the end incidents are unrecognizable. I wouldn't even have thought about it in Bonnie's case, only I had a very interesting discussion about Anna Kournikova with my brother, a super knowledgeable sports nut who lives in England and has been following Kournikova's career since its start. When I first mentioned to him that Kournikova was going to be one of the Biggest Loser trainers, the first thing he said was "I see. Well, expect her to antagonize her team which is going to lose pretty badly from the start." I did mention to him again that what he had predicted happened, only I thought that older people lose weight with greater difficulty and cannot always perform as well as the younger ones, and maybe this was the reason, rather than Kournikova antagonizing them which I hadn't really noticed. His retort was that older people do lose weight, and that there have been many older people who did very well on TBL, including a winner (they get the show on cable in the UK). Moreover, he believed that reality shows are heavily edited, and that he happens to know more about Kournikova than I do, which is, after all, very true.
One thing that he also remarked was that he hated how the show made a big deal out of her being a great athlete, since Kournikova was a notoriously bad player for the level she was playing, and that much of what she accomplished, which wasn't so much, was because of her personal beauty and appeal. Her career had initially shown promise when she was very very young, but she hadn't really won any major titles later, when it really mattered.
Anyway, as I said before, I don't know personally, and I haven't really noticed this, but at the same time, I cannot ignore what my brother says because I haven't met his like sports-nut-wise in my life!