He went from being a primary school pupil in the now-defunct Trim And Fit (TAF) Club, an exercise programme in schools for overweight children, to being anorexic at age 15.
Mr Lim, who is now a university student and does not want to be identified, says he felt embarrassed in primary school when he was made to go on the school hall stage as a reprimand for skipping TAF Club during recess.
Tired of being laughed at for his weight, he went on a diet in Secondary 3. He cut out Coca-Cola, which he previously could drink an entire 1.5-litre bottle of in a day, and stopped eating deep-fried food.
Getting compliments on his initial weight loss "encouraged" him. "When I saw my weight going down, it made me feel like I should continue. My mind was entirely focused on losing weight," says Mr Lim, 23.
It was a slippery slope. He started to diet excessively and jogged six times a week for about 30 minutes each time, stepping on the scales every day to keep track of his progress.
Originally weighing 85kg, Mr Lim became severely underweight. His body mass index plunged to a level that was below the first percentile for boys his age.
He lost so much weight during that year in secondary school that some of his classmates did not recognise him. He wore a jacket under the blazing sun because he felt cold as a consequence of having too little body fat.
His relationships with friends and family suffered. Formerly gregarious, he kept to himself to avoid being asked to eat in the canteen with his classmates.
He had "frequent quarrels" with his parents, for example, when his mother bought regular eggs but he wanted eggs with Omega-3 fatty acids, which he perceived to be healthier.
His parents' pleas to him to join in family meals fell on deaf ears - he preferred to hole up in his room or go to Starbucks, where he drank sugar-free coffee with skimmed milk and revised his homework.
His teachers realised something was wrong and his school counsellor referred him to a hospital, where he was diagnosed with anorexia nervosa, an eating disorder characterised by an abnormally low body weight and an intense fear of gaining weight.
They were terrified of becoming "too small". They said they were scrawny and pathetic, even though they were overweight with muscle.''
DR KEN UNG, a consultant psychiatrist, on male patients with body dysmorphic disorders who worked out compulsively to build muscle bulk
He was hospitalised for 13 days, gaining 5kg with the help of doctors, psychologists and dieticians. However, recovering from anorexia took another five years.
Even now, "it is not 100 per cent recovery", says Mr Lim. He has struggled emotionally with having to regain weight and still avoids certain calorie-laden dishes such as laksa.
While eating disorders are much more common in women than in men, as a teenage sufferer, Mr Lim was in a prime demographic for men with eating disorders.
According to a study of male patients who were treated for eating disorders at Singapore General Hospital (SGH), the mean age of these patients at their first medical consultation was 19.9 years.
Mostly students and men doing their national service, they had generally been unwell for three years before consultation, said the study from SGH, which has the country's only dedicated centre for the treatment of eating disorders. One in three patients also suffered from depression.
Published last year, the research surveyed 72 cases over nine years, from 2003 to 2012.
Less than 10 per cent of SGH's patients with eating disorders are male, says Dr Victor Kwok, a consultant at the hospital's department of psychiatry, who was not involved in the study.
Historically, the ratio of male to female sufferers of eating disorders has been 1:10 in the general population, he adds.
Anorexia is rarer among men than other eating disorders such as bulimia nervosa and binge-eating disorders, says Dr Kwok.
Men with body dysmorphic disorders might ask for repeated plastic surgery for body parts they view as abnormal, he says.
Dr Ken Ung, a consultant psychiatrist at Adam Road Medical Centre who has worked with patients with eating disorders for 20 years, has encountered male patients with body dysmorphic disorders who worked out compulsively to build muscle bulk.
"They were terrified of becoming 'too small'. They said they were scrawny and pathetic, even though they were overweight with muscle. One guy force-fed himself with food and calorific supplements," says Dr Ung.
He cautions that eating disorders can be fatal. For example, cardiac death can result when the electrolytes in one's body are imbalanced because of purging, a common behaviour with eating disorders.
Eating disorders in men may be difficult to detect "because some of the symptoms may seem normal, for instance, eating only broccoli and lean chicken, or exercising for hours in the gym", says Dr Kwok.
A man's binge-eating could also be dismissed simply as having a "hearty appetite".
"It is also embarrassing to talk about eating disorders because it is more commonly associated with women," he says.
"Some parents may not be aware that their child may be suffering. There have been cases where patients brought their parents to see me because they wanted them to be more aware of their illness and to help them."
Madam Tan, a housewife whose son, now in junior college, had bulimia for 11/2 years in secondary school, says it could be "hard to separate between the eating disorder and normal teenage rebellion".
There had been "a bit of rolling of the eyes and not wanting to give a lot of information" on the part of her son, which she thought was normal teen behaviour.
He became more withdrawn when he developed bulimia, an eating disorder characterised by binge- eating and purging.
When their son started losing a lot of weight, Madam Tan, 50, and her husband confronted him about his dieting. It was only a few months later that he agreed to seek medical help.
Initially frightened of the bulimia that was "destroying" her son, Madam Tan says she and her husband - who have another child - presented a "united front" in helping their son beat the eating disorder.
"You're fighting a war, basically. You can't have two generals. We agreed on how we would approach the problem."
Some ground rules were that their son could not play one parent against the other and there was no negotiating about the appropriate amount of food he had to eat.
Their son recovered from his illness following treatment that included working with a nutritionist and a psychologist, and undergoing therapy together with his parents.
In general, Dr Kwok says parents can play a role in helping their children have a positive body image.
"Families should not be too fixated on body size or shape. Some family cultures involve criticising one's children (about this). There is no need to conform to societal ideals. Try to build up self-esteem and don't let your own body issues affect your children."
Stress one of the causes
"As with most illnesses, eating disorders cannot be attributed to a single cause," says Dr Victor Kwok, a consultant at the Singapore General Hospital's department of psychiatry.
"However, there can be a trigger, such as examination stress from the O or A levels; transitioning years in school, such as Secondary 1 or 3; or the first year of polytechnic or junior college."
Other factors are biological, such as changes in chemicals in the brain; psychological, such as low self-esteem or personality traits such as perfectionism; and social, such as relationship or family problems.
Mass media images of very thin models and celebrities have stirred contentious debate about their alleged links to eating disorders in women.
Similarly, Dr Kwok says some men with eating disorders might have "internalised media images of men with a muscular physique that is often unrealistic".