It is seen as a low calorie energy boost, but too much coffee could still make you put on weight.
Experts say drinking five or more cups a day could increase the amount of fat stored in the abdomen.
Chlorogenic acid, a compound found in coffee, has been linked to reduced risk of diabetes, lower blood pressure and even combating fat.
But a study of the supposed benefits found feeding mice a high dose of the substance actually caused their cells to retain more fat.
"The real message is that we need to have coffee in moderation," said assistant professor Vance Matthews, of the Western Australian Institute for Medical Research. He said three or four cups could improve health - but more put the drinker at risk.
