BOONAH mum Kate Bennie is a slim, physically active person so when doctors told her she was at risk of a heart attack or stroke, she was shocked.
One health expert described her as "a walking heart attack".
When Ms Bennie went for a series of tests she discovered her cholesterol levels and triglyceride levels, a type of fat found in the blood, were off the charts.
The results were a huge wake-up call.
"I could always eat whatever I wanted and I never put much weight on, so even though my meals were fairly healthy, I had way too many treats and ate a lot of chocolate," she said.
"I thought I was getting away with it and I would definitely say that being normal weight gave me a false sense of security.
"All my cholesterol results were bad but my triglyceride reading was off the charts at 19.2. Normal is under 1.7 and anything over six is considered very high.
"I found out that a high level of triglycerides is dangerous and it's scary to think I was three times the level that is considered very high - I was a walking time bomb.
Ms Bennie's health issues went undiagnosed for a long period of time, just like many other at-risk normal weight Australians, a health expert has warned.
Exercise physiologist and nutritionist, Naomi Ferstera said many slim people assume that they are healthy when in fact they are walking heart attacks.
"Sadly, many people are completely unaware they have cardiovascular disease until their first heart attack or stroke," said Ms Ferstera.
"Despite CVD being the number one killer in Australia, there are currently no statistics on the number of MONW individuals, though it is likely to be in the thousands, possibly tens of thousands.
"We can't hold on to this idea that body mass index is the most important health factor, it's a stock standard formula that doesn't take into account many important elements for good health.
"Fat around the heart can lead to heart failure or heart attacks and fat around the liver can promote non-alcoholic fatty liver disease - a significant health concern contributing to many serious conditions," she said.
Ms Bennie said after making changes to what she eats and her exercise regime, her cholesterol levels returned to almost normal.
"I feel like I dodged a bullet," she said.
"I went on a low carb high fat/keto diet, started intermittent fasting and changed my exercise routine. I was relieved to see positive blood test results nine weeks later."
Update your news preferences and get the latest news delivered to your inbox.