If they are not treated they can require a lot of medical help which can be very costly.
"If they can get the weight off they can improve their health and mobility and maybe contribute to society rather than being a burden.
Mr Martin, who used to spend his days playing video games and watching TV, explained in 2012: "I started eating to ease the pain and before I knew it, I was binging every time something upset me. I am an agoraphobic - I'm afraid of public places - but it was never treated.
"I just want to be happy, without needing food to make me happy." The Big Short, the film adaptation of Michael Lewis' book of the same name about the causes of the financial crisis, opens in UK cinemas this weekend.
His voice: rich and replete with facts from that trusty Bradshaw’s handbook, lulling us into dreams of British might and innovation as our glorious countryside hurtles past.
Such has been the enormous popularity of his Great British and Great Continental Railway Journeys series that the once Tory hardman and Cabinet minister has created an entirely new public image for himself.
"In Keith's case, it's a shame because he'd had successful surgery despite being high-risk because of his size. "Bariatric surgery can be a very good thing for the people who need it. Once a patient hits a BMI of 30-35 it is extremely difficult for them to lose weight on their own.
Take care of each other." Mr Martin's weight ballooned after he became seriously depressed in his twenties.
He blamed blamed the bingeing on depression and anxiety which he developed after his mother died - also of pneumonia - when he was 16.
As we approach a vote on the UK's membership of the European Union, we look at what 50 writers, actors, historians, artists and comedians have said about Europe and its nations.
There is the politician-turned-presenter relaxed in some polished-wood carriage, hair coiffed, clothes all stripes and pastel shades like deckchairs arranged on Brighton beach.