Entries for the Simplyhealth Great Bristol Half Marathon are open. Enter at: Greatrun.org/Bristol

An overweight police officer who became ashamed to play rugby in front of his son lost a staggering eight stone in 18 months and transformed himself into a half marathon runner.

Sean Underwood, from Thornbury, played rugby for Thornbury Rugby Club for most of his life. As a police officer who worked shifts, Sean relied on fast food and takeaways, eating them twice a day on occasions.

His weight reached 23 stone and by January 2016, during a rugby match where he struggled to run in front of his nine-year-old son Ryan.

Sean vowed to change his lifestyle and joined a slimming class the next day. He then started running as a way to increase his exercise and the weight began to fall of him.

In just a year and a half, Sean lost a huge eight stone, taking his weight down to 14 stone. He ditched his daily takeaways for fresh food alternatives and now tries to run once a day to keep his fitness levels high.

Sean has also seen a huge difference in his work in the police force, having more energy to take on the physical role.

Sean set himself goals by signing up to running events in order to keep his motivation high and this year he will take on the Simplyhealth Great Bristol Half Marathon with his wife Rachel when it returns to the city on Sunday 17 September.

Sean, 37, said: “I have always been very active and loved to take part in sport, which always comes to a surprise to people as back in 2016 I was sitting on the wrong side of 20 stone!

“From a young age I played rugby with Thornbury and loved sailing but the sheer amount of bad food that I used to eat meant that my weight started to increase.

“During shifts I would eat things like Mcdonalds, cakes, white rolls filled with giant portions as well as chocolate and fatty drinks.

“I also drank cider and ate things like burgers on my days off and would never say no to a take away curry!

“It felt like I was addicted to food and that because I was taking part in sport, then it was fine.

“But one day when my son Ryan came to watch me play rugby, I was embarrassed at how slow I was, I couldn't run around the pitch like the other players and it was awful for him to see me like that.

“I decided that I wanted to change my life and I joined a slimming group who helped teach me about the right choices that I had to make.

“I stopped having takeaways and always freshly prepared my own meals with healthy alternatives. I felt like I had so much more energy and so I decided to take up running.

“At first it was extremely hard, I couldn't even run for one mile without stopping! But after a while I was able to go further and the weight literally started dropping off me!

“I've now reached my target weight of 14 stone and it feels amazing, I've been on a huge emotional journey.”

Sean will join 10,500 runners for the Simplyhealth Great Bristol Half Marathon on a scenic route that makes the most of the city's picturesque backdrop.

The city centre run has become a long-held tradition in the sporting calendar, starting and finishing in Bristol's historic harbourside.

The sea-level route takes runners along the stunning Avon Gorge, passing under the iconic Clifton Suspension Bridge twice before returning to the city centre.

Sean took on the famous half marathon last year, completing a huge personal goal and hopes to beat his time when he returns in 2017 as a super slimmer.

He has documented his progress via his online blog called ‘Undie's Journey' showing the highs and lows of his training and weight loss.

He added: “Running was never my thing before I started my journey to lose weight, in fact I hated it!

“Over the last year I have developed a love for it, I even joined a running club because I wanted to get involved and I thought it would be a great way of keeping motivated for the event.

“I started by running for a while then stopping and walking. I am now worlds away from that and it's still hard to believe how far I have come.

“I took on the Simplyhealth Great Bristol Half Marathon last year and so I can't wait to come back this year and hopefully beat my time with Rachel by my side.

“When I started I didn't know what to expect or how fast I would be able to lose weight but I never imagined that I'd be able to lose eight stone!”

Entries for the Simplyhealth Great Bristol Half Marathon are open. Enter at: Greatrun.org/Bristol