It started off being once a week, but she was soon throwing up sometimes twice a day. Her grades started dropping and the previously confident and bubbly schoolgirl became withdrawn and distanced herself from her friends.
The illness took over her body - her hair fell out, she broke out in pimples, and a dentist told her if she didn't stop, all her teeth would fall out. She once had to get 19 fillings.
Ms Guy is investigating eating disorders for a story for TV3's 3rd Degree.
Women's Health Action Trust director Julie Radford-Poupard applauded her for openly discussing her battle with bulimia.
"People don't realise that poor body image can also lead to higher rates of depression, increased rates of bullying and reduced physical activity, poor sexual health. It's much wider than people think it is."
However, there is no helpline for people battling eating disorders to call after the Eating Difficulties Education Network (EDEN) closed late last year due to funding cuts.
"It's heartbreaking - a real shame," Ms Radford-Poupard said.
Eating disorders
How many people develop eating disorders?According to figures from the New Zealand Mental Health Survey in 2006, 1.7 per cent of the population, or 68,000 New Zealanders, will develop an eating disorder some time during their life. Bulimia nervosa is twice as common as anorexia nervosa.
Who gets it?
Females represent approximately 90 per cent and males 10 per cent of all eating disorders.
Average duration?
It typically takes 5-6 years of treatment to recover - 60 per cent fully recover, 20 per cent partially recover and 20 per cent never recover. Typically recovery from bulimia is faster and the success rates are higher than for anorexia nervosa.
How to get help
Talk to a trusted friend or family member and your medical professional who can help you to choose the correct path to recovery.