I’ve just watched it and although the advice given wasn’t what most people here would do I think the family involved especially the lady wouldn’t have accepted a low carb diet anyway. She wasn’t changing a tin of beans so there’s no way she would have agreed to cutting out potatoes, bread etc.
At the start the lady said she was told that if they lost weight there’s a good chance they could reduce and even stop their medication I think this is the route the tv show went down. Looking at the bigger picture of seeing how awful their diet was of chicken nuggets and chips to changing it to more fruit, veg, vitamins. If your going to eat porridge surely it’s better to have a handful of fruit on it instead of syrup? At least then your getting fibre with it?