A Tube Map diet isn't about surviving on left over pizza, rat kebab and pigeon pie. It's the challenge to spend a week only eating food that is grown or reared within the spread of the London Underground map.
It's not too easy but he manages to find a couple of city farms, some farmers markets and some honey produced in Regent's Park.
He could have tried the other challenge of surviving on food from Tube stations. Unless you're lucky enough to use a station with a Marks & Spencer's in it, you're stuck with newsagent fodder or the odd samosa, chicken roll and doughnut from Treats.
I suppose the advantage of not having much decent food on sale within very close vacinity of Tube stations, means that you get fewer people eating smelly food on it. If I'm particularly starving and have a had a few drinks I've been known to forget Tube etiquette and tuck into some fried chicken. I try to keep it in the bag as much as possible when I'm not gnawing on it, but am still aware of the evil stares of people and subtle nose wrinkling going on.