So, people don't want advice on diet from a fat GP - or from anybody who is overweight. But if we are honest, most of us, the fat, don't really want advice on dieting from a skinny person either.
Unless, and it is a very big 'unless', the skinny person who is giving the advice was once a colossal wobble-bottom. 'This,' we say to ourselves, 'is a person who knows what it is like to be a proper bloater. This is not a celebrity whose version of being fat is being normal size, and whose idea of a diet is cabbage.'
So, I'm going to say that I would take advice from chef Tom Kerridge - he likes food, he's in a kitchen all the time, and he has lost 9 stone. And he can't have had any surgery to do it because he's a chef and so he probably needs to be able to eat his own food in a normal way.
And he did it by cutting out booze and doing more exercise. It is almost as though you have to take in fewer calories and exercise more.
But surely it can't be as simple as that?