Drinking coffee, regardless of its health benefits, as long as it's taken by five cups a day, leads to weight gain and diabetes risk.

Whereas before studies said that higher doses of coffee could help weight loss and maintain it, a new dietary study published in the Journal of Agricultural and Food Chemistry suggested otherwise. Conducted over a period of 12 weeks in overweight male mice, researchers from the Western Australian Institute for Medical Research and the University of Western Australia discovered that consuming more than six cups of coffee per day led to the abnormal retention of fat within cells. And this is regardless if your coffee is decaffeinated or not.

"It would be safe for people to consume one to three cups of coffee a day, but I think when you're getting to the upper end of four or five cups of coffee, which is not uncommon for people to be consuming that," the Institute's Associate Professor Vance Matthews said.

"That's where you really do have to be careful."

Researchers found that the chlorogenic acid (CGA) supplementation resulted in vast accumulation of lipid in the liver.

CGAs are known for a lot of their health benefits, including minimising body fat accumulation, increasing insulin sensitivity, as well as reducing blood pressure.

"There was an approximately 30 per cent increase in the lipid levels in the liver of those mice with the very high levels of CGA."

When the equivalent dose of CGA in five or six cups of coffee per day was fed to lab mice, it affected the way fat was used in the liver, causing abnormal retention of fat within cells.

Moreover, researchers noted that a higher degree of glucose intolerance and increased insulin resistance was seen among the obese mice.

"Up to three to four cups a day still seems to decrease the risk of developing diseases such as cardiovascular disease and type-2 diabetes," Mr Matthews said.

"Everybody knows about the effects of caffeine, but when we're considering our lifestyle choices it's important to remember that compounds such as CGA can have an effect on our health if they're not consumed in moderation."