The study was first in the world to look at higher doses of coffee, rather than the equivalent of one or two cups, and it found that five coffees doubled the fat around organs in the abdomen - a type of fat that causes deadly conditions.
A compound in coffee known as Chlorogenic Acid (CGA) was thought to have health benefits, such as preventing diabetes, but the study found too much of it may cause a build up of fat and other health problems.
The researchers found that mice given an equivalent dose of five cups of coffee for a human developed twice the amount of visceral fat - the most dangerous form of fat that collects around the organs in the abdomen.
University of WA professor Kevin Croft said that previous studies had only tested small amounts of coffee equivalent to one cup of coffee a day, news.Com.Au reported.
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"The CGAs were previously known for their health benefits - increasing insulin sensitivity and reducing blood pressure and body fat accumulation," he said.
But the study proved the opposite when dosages given to mice were equivalent to five cups of coffee for a human per day, said WAIMR Assistant Professor Vance Matthews.
"We found that the equivalent of five cups of coffee a day had a tendency to increase weight gain, particularly in regards to visceral fat," Matthews said.
Matthews also warned people against weight loss products containing green coffee beans, which could have high levels of CGA and thus cause weight gain.
"When you have lower doses of CGA there is promotion of beneficial pathways that can break down fat, but with high levels you actually have pathways that are disregulated and you start seeing bad effects," he said.
"The real message is that we need to have coffee in moderation," he said.