After joining her local Weight Watchers class and following a simple exercise programme of swimming, walking and gardening, Mrs Whitfield slimmed down a healthy 8st 7lbs - a move she believes has prolonged her life.

BBC: 'Weight loss has prolonged my life'

Nevertheless, Weight Watchers is revamping its product with the launch in America on August 17th of a new programme called Flex Points, which is supposed to be easier for slimmers to follow.

ECONOMIST: Dieting