Obesity was common in wealthy English of the 18th and 19th century, but here’s a doctor who put himself on an impressively drastic diet. This is from the Chester Courant of 1809:
Resurrection of Corpulence
The celebrated Dr Cheney, of the last century, by an abstemious diet so reduced himself as to be able to draw his enormous loose skin from the top of his back, over his head like a hooded serpent – incredible as it may appear this was positively attested by an old physician of the first eminence at Bath who knew him well.
He sounds like a lot of fun at parties!