Yes, you can actually break a habit. It's called extinction. Now, that does not mean that a habit cannot reemerge given the right environmental triggers, as the author does note. But it's a little disingenuous to say that you cannot break a habit. Ask any behavioral psychologist. Or neuroscientist, for that matter.
Your brain is a little more plastic than this idiot wants you to think it is.
However, since she's talking about weight lose and appetite... yeah, I don't know if you can break free from that whole 'neural regulation of caloric intake' thing that triggers hunger and feeding behavior when your body has less than its normal level of fat stores.
That's a slight difference from "breaking a habit", and good luck with that one.