David Marshall, or the Bodydoctor, is personal trainer to the stars. Well, quite a lot of them anyway. His studio gym in St John’s Wood is frequented by models, actors and movers and shakers from the world of TV and music. He trained Dani Behr for her television series Dani Dares, during which she passed a commando fitness course with 95 per cent fitness. As an ex-footballer himself, he’s worked with David Ginola and Les Ferdinand, as well helping thesps shift unwanted kilos for particular roles. Self-taught, he’s been perfecting his regime for the past 15 years. With a belief that you’re supposed “to work with your body not against it”, Marshall’s work-out is based around a lot of fat-burning cardiovascular exercises coupled with weight-training complementary muscles while keeping the neck and other parts of the body completely relaxed.

So, as I walk into his multi-gym complex thing, I am secretly dreading the next six weeks. Marshall bounds over, barefoot in baggy shorts, with a Noel Gallagher haircut, all full of cheeky chappie charm. “R-i-i-i-ght,” he says in a faux Mancunian accent, “Let’s take a look at you.” Wired up to a heart monitor, I’m made to do a round of the gym – rowing, cycling, pulling on various machines followed by what feels like 30,000 situps in one of those “hey, you, fat person!” harnesses that you see in the Sunday papers. After all that, my heart rate is quite low, as a result of being fit as a child. Next come the fat-squeezing crampons, testing to see just how much adipose my body has managed to squirrel away in the past 30 years. Grabbing great chunks from underneath my upper arm (21.7mm), around my waist (27.2mm) and underneath my shoulder blade (16.3mm), David then proudly announces that I’m a healthy, or rather unhealthy, 38 per cent fat. He then makes me stand on a pair of scales that send an electric shock through your legs, from foot to foot, timing how long it takes to get through the mounds of flesh.

So there I am, standing in the studio multi-gym in my new trainers (first bit of retail therapy in ages), I’m 38 per cent fat, my chest is 39.3/4inches, my waist is 37.1/4inches and my thigh 24.1/8 inches. Things are not looking good. I have a six-week programme ahead of me… No alcohol; three litres of water a day; protein and vegetables after I’ve trained, vegetables and starch when I haven’t. No dairy or fat. Four times 1 1/2-hour work-out sessions a week, swimming on my days off. It sounds do-able with a bit of cheating here and there. “Most importantly,” I say, “d’you think you can get me down to at least a slim size 12?” “‘Course,” he says with a smile. “Trust me, I’m a body doctor.” The Bodydoctor can be contacted on 020 7235 2211or The Bodydoctor’s website. Fees are £60 a session Next week: how much has she lost?