Oh you can be very fit and eat badly.
Usain Bolt had a McDonalds before he broke the world record
.
A lot of my undergrad students eat dreadfully, yet they're up at the crack of sparrows to row. Many of them drink like fish too and some smoke (though that is increasingly unpopular).
You can also be thin and eat badly.
As for the Olivers and the Camerons, well, of course they have help on the domestic front and lots of money. Time and money spent on grooming.
The hands on thing is an odd one. Obviously the Olivers' brand is built on them being down to earth, accessible types (and I suspect they were when it all beagn twenty years ago).
But the reality today, is that their lives are far removed from your average Joe punter. Obviously, they still have a vested interest in presenting themselves as 'normal' as possible, because they want to sell us stuff.
Sam Cam is a little wiser in that she keeps her gob shut.