Even her family members called her names like "little pig" in Mandarin, though she feels they were more terms of affection.
It was only when Ms Bi was in Secondary 2 - she weighed her heaviest at 78kg and stood at 1.66m - that she decided to do something about her weight.
"I started caring more about my image," she says adding that she was also spurred to lose weight when she noticed many of her slim schoolmates had boyfriends at the time.
She followed YouTube videos on cardio exercises and worked out up to an hour daily and jogged three times a week. She also ate more vegetables than rice and avoided sweets, tidbits and carbonated drinks.
She lost about 18kg over two years, but her mother, Ms Sue Anne Kuek, 57, raised concerns over her daughter's dramatic weight loss.
"I was worried that she was overdoing it. Weight loss should be a gradual process," says the assistant manager at a country club who is married to a 52-year-old graphic designer. They also have a son, 23, who is an undergraduate.
Ms Bi stopped what she calls her "obsession" with losing weight last year because she wanted to focus on her N-level examinations.
Her mother is now proud of the efforts she made to lose excess weight. "It was hard work. I respected her determination to do something for herself," says Ms Kuek.
In the case of life coach Karen Evers-Foo, 46, being plus-sized meant enduring humiliation from a young age and consequently wanting her children to have a good body image.
In secondary school, she was curvy though not overweight, but slimmer girls passed snide comments about how she was too fat to wear trendy clothes.
At 26, she was diagnosed with an underactive thyroid, the cause of a puzzling gain of 10kg in less than two months.
Family members urged her to lose weight and a former female boss advised her to look "presentable". Salespeople told her they did not stock her size. She has clocked looks of "disgust" and faux concerns about her "health" aimed at her. When she was single, she was rejected "many times" on dates on account of her weight.
Now about a UK size 18, she says: "When I had a daughter, I was determined that I wasn't going to let her have a poor self-image. I want her to see that everyone deserves love, everyone deserves to feel good about themselves.
"It is difficult to be body-positive in this part of the world, where the majority of Asians are on the slender side."
She has a 14-year-old daughter and a 17-year-old son, and is married to a 46-year-old technical project manager in the telecommunications industry.
Wanting to be part of a body-positive community, she took part in the inaugural Ms Amazing Plus Size Beauty Pageant in 2010, where she was second runner-up.
Over the years, she has told her daughter, Isabela, who at 1.74m is slightly taller than many of her peers, about having a good selfimage, regardless of one's size.
It seems to have paid off.
Isabela, a Secondary 2 student, says these conversations with her mother tend to be short, simply because she does not face any challenges regarding her body image.
"She always taught me to have a positive body image," she says.