The Men Who Made Us Fat: Are you TOFI?
I'm here for a scientific trial as part of the television series I'm making for the BBC - The Men Who Made Us Fat.
I came up with the idea for the series a while ago as I was watching the original version of Willy Wonka and the Chocolate Factory from 1971.
I wondered how in the space of 40 years we could have changed our idea of what is fat so drastically.
Jacques Peretti has his hidden obesity levels checked
So having authored the series and worked in partnership with FreshOne Productions and the BBC to get the series made, here I am in the above video clip - at Hammersmith Hospital about to discover how fat I really am.
Dr Bell specializes in analysing not the external fat of patients but the internal fat, and the shocking truth is that it's not just the obviously obese who are in trouble from their diet.
It could be all of us.
I'm not particularly worried as I put on my blue gown and am lowered into the space-age chamber.
I cycle to work, I walk up escalators and play the odd bit of football in the garden. I'm by no means a health nut but I do enough physical activity to remain relatively fit, or so I think.
For half an hour I must lie perfectly still as a scanner moves up and down my body creating a detailed image of every last inch of fat.
"There will be no hiding place for your fat," Jimmy tells me ominously.
Then it's all over, I take off my headphones and re-join the world, sitting in Jimmy's office to go through my results.
On the outside, Jimmy says I am fit.
"There is very little external fat," he tells me.
"But on the inside," he says, gesturing to the scan ominously "your liver is swimming in fat - four to five litres."
Four to five litres!
In all honestly I was so shocked by the results of the test that I found it difficult to continue interviewing the professor properly.
On average we are all three stone heavier than we were in the 60s, and for the vast majority of us the fat is internal.
Jimmy calls us 'TOFI's' (Thin Outside Fat Inside).
Worrying as this realisation is, on reflection it makes sense.
It shows the degree to which sugar, which as many of the programme's contributors explained to me can be a major contributor to obesity, is present within our everyday diet.
Having just discovered I was a TOFI I want to quiz Jimmy on what I could do to reduce the amount of internal fat I was carrying.
Secondly, short, sharp bursts of sprinting, 30 seconds at a time three or four times a week. It mimics what we did as hunter-gatherers and burns off the internal fat.
Now if only I had the willpower to put that advice into practice!
Note: Due to the extended Wimbledon coverage, the third and final episode of The Men Who Made Us Fat has been rescheduled for Thursday, 12 July at 9pm on BBC Two. It will be available to watch in iPlayer for the following seven days.
Update 4 July: Episode one and two have unfortunately now expired in iPlayer because of a break in the run of the series due to the unavoidable schedule changes.
However, all three episodes will be available in iPlayer when they're repeated as part of the Sign Zone starting on Wednesday, 11 July at 2.30am on BBC One. Please see the episode guide for further times.
Comments made by writers on the BBC TV blog are their own opinions and not necessarily those of the BBC.