Red Road: A Calcuttan settled in Hyderabad who took to running to lose weight is the fastest Indian in the Ironman 70.3 triathlon.

He recently gave up his job with a top accounting firm to devote more time to races around the world.

Anubhav Karmakar, 30, has run in various places but Sunday's Tata Steel Kolkata 25K, partnered by The Telegraph, was his first hometown run, an experience he said he "thoroughly enjoyed".

"There's been a happy buzz in the racing circuit for the past year or so about a new racing culture in my hometown... I really wanted to experience it. I was so happy to see the large turnout and how well the race was managed," he said.

Karmakar finished the 25K in one hour 42 minutes, the second best in his age group.

Ironman 70.3 is a 113km triathlon organised by the World Triathlon Corporation. It involves a 1.9km swim, 90km cycling and 21.1km run.

Karmakar became the fastest (five hours and two minutes) among Indians on the circuit in Turkey earlier this year.

The Ironman sees 200-odd Indian participants. The ones with the most points are named the best in their category.

"I gave up my job in July because I wanted to pursue triathlons seriously," Karmakar said from New Town where his parents live. "I train people online in six Indian cities. They are either trying to get better at marathons or preparing for ultra marathons such as the Comrades in South Africa."

He said he found triathlons "fascinating" because it tested endurance and stamina and required a lot of strategising. "You have to pace yourself perfectly in various settings under different weather conditions... it is challenging as well as exciting."

The engineering graduate and management postgraduate used to work in Deloitte as a senior consultant.

He was born in Calcutta but he studied in various cities as his father had a transferable job.

His 78kg weight for his 5'4" height made him obese when he started working in 2011. "I was worried about my health... that's when I started gymming to lose weight and two years later I took to running."