An Ashford dad who transformed himself from a 20-stone diabetes patient into an endurance cyclist will jump onto the saddle for a 100-mile charity bike ride.

Geoff Whitington, the star of the film Fixing Dad, is kicking off his fundraising for the Ashford-based Paula Carr Diabetes Trust with the ride at the end of this month.

Fixing Dad, which was made by Geoff’s two sons, shows how they helped their father change from a type 2 diabetes patient into a lean and mean cyclist, and will be aired on BBC2 this weekend, ahead of the event.

Geoff and his son, Anthony, are taking on the Prudential RideLondon-Surrey 100 on Sunday, July 31, in what will be their first fundraising challenge for the charity.

The documentary was produced by Anthony and his brother Ian, both experienced film-makers, and charts the family’s amazing journey to change their dad’s lifestyle.

The Paula Carr Diabetes Trust helped finance the film, so Geoff and Anthony are ready to give back to the charity, with Ian filming the pair taking part.

Geoff said raising money would be their way of supporting the charity which has helped them so much, adding: “This is only the start of the fundraising we’re aiming to do for the Paula Carr Diabetes Trust.

“Without their help the film wouldn’t have been possible. We owe them big time for what they’ve helped us achieve.”

He was a self-confessed couch potato working as a night-time security guard before starting his health drive two years ago.

He was told by his doctor he risked losing a foot due to complications related to his diabetes and had developed Charcot foot – where the arch of one foot had collapsed – and his other foot was developing ulcers due to poor circulation.

But now, feeling fitter than ever before, Geoff is looking forward to taking on the challenge around the capital and through the Surrey countryside.

Fixing Dad will be on BBC2 this Sunday at 10pm.