Thing is, in my view, most of these programmes are for those, settling into their sofas on a workday evening, to pass some time before whatever takes their fancy for drama at 9pm. Their audience is there to be entertained, as much as anything.
It is a shame, but how, in an hour, do you get these big messages across, when for most folks, post diagnosis, there is a period of denial, then a requirement for a suspension of belief (about wholemeal, calories and particularly fats), before any form of embracing occurs.
(Full disclosure, I haven't been able to cath up with the programme yet, so my response in clearly a generalisation, based on apparently similar programmes in the past.)