Looking at the well-built man, one would not imagine that he struggled with anorexia and bulimia for nine years.
"People tell me they don't think men would have anorexia. But I have battled it," says Mr Ford Lim, a 27-year-old pre-school principal.
"I had been overweight since I was eight. I was in the Trim And Fit club from the time I was in primary school all the way until Secondary 4.
"I was constantly bullied. Boys would come up behind me and grab my chest.
"It was very demeaning."
Mr Lim started running after he entered polytechnic. Spurred by the initial weight loss, it quickly became an obsession.
When he was 18, he lost close to 30kg in three months, dropping from 85kg to 56kg. "I was eating just fruits and vegetables - no meat, no carbs."
He became bulimic.
"I would eat and then lie to my friends, saying that I had to go to the toilet because I wasn't feeling well. But I was actually throwing up."
Then anorexia kicked in.
He would starve the entire day and binge during dinner.
At his lightest, the 1.74m-tall man weighed 52kg. He was 24.
By his own sheepish admission, at one point, he looked like a "clothes-hanger".
But one incident changed it all.
"My Mum came back from New Zealand and she was staying with us. One day, she cooked a meal," he recalls.
As usual, he headed to the toilet after eating.
"I was bent over the toilet seat, throwing up all the food she had painstakingly cooked. The next thing I saw when I turned my head was her standing at the door, looking at me," said Mr Lim.
"That broke my heart."
It took the combined efforts of his family and his own willpower to start the two-year process to recovery.
"I just wanted to be a better person. I was just sick of being a slave to something that was controlling me."
He is also grateful for his girlfriend, who has supported him throughout.
He says: "She has been unbelievably supportive. I wouldn't be where I am if not for her."
Mr Lim took up a programme for training endurance, strength and cardiovascular fitness, and credits it for his positive outlook today.
As he gears up for the competition next Sunday, Mr Lim says: "It is possible to overcome eating disorders but it takes time.
"However, like quitting smoking, once you put your mind to it, chuck it and never look back."