As a fairly new viewer to selly telly (uni project) I'm can only comment on her behaviour recently, obviously the people on this forum knew her a lot better than me, but to me she appears to be totally stressed out.
I know her husband sold his PR company last year, because he was looking for new challenges and ventures. Maybe things haven't worked out the way they had planned and it's stressing her out. After all the PR lifestyle is not cheap to maintain. You don't present business ideas and PR pitches over coffee in Starbucks.
In relation to her weight issues, lots of people use exercise to cope with stress but it's easy to get caught up in a vicious circle, you exercise to relieve stress, but to much exercise causes more stress, so you exercise more, and so it goes on until either you develope mental health issues or your body just packs up on you. But Jill strikes me as the kind of person who would not ask for or accept advice from people, no matter how well meaning, so continues on her vicious circle. Might also explain her obsession with green smoothies, after all they are meant to do everything for you other than washing the dishes and hoovering the carpet, but I'm sure Jason Vale is currently working on that.
Just as a side note, Jill's husband once said in an interview that when he's preparing campaigns he gets so emmersed it almost becomes an obsession. Secondly, a writer commenting on the sale, wished Larry Luck, but suggested he may have to tone down his abrasive attitude and aggressive pitching style, as it did not sit well with current media gods.
Three words strike me as interesting, obsessive, abrasive, aggressive, remind anybody of a certain QVC presenter.