An obesity expert from London, Tim Lobstein, said previous findings that small amounts of alcohol lowered heart disease risk were taken from surveys more than 40-years-old.
Studies have indicated alcohol may raise levels of good cholesterol and be beneficial to blood vessels, while antioxidants in wine are thought to protect arteries.
"But we were concerned that the findings may not apply to our modern, fatter population," said Lobstein, an adjunct professor at Curtin University's Public Health Advocacy Institute in Perth.
Researchers revisited the data and found the protective effect held for slim men, but not for those with a Body Mass Index above 27.5, The Sydney Morning Herald reported.
An index of 26 to 30 is considered overweight.
"We need to check other surveys and see if they show the same pattern, and we need to check the data for women," Lobstein said.
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"Given the link between even small amounts of alcohol and many common chronic diseases, any heart-healthy effects are likely to be outweighed by other risks. It is best to say that there is no safe level of alcohol consumption, especially if you are overweight," Lobstein said.
The Heart Foundation's director of cardiovascular health, Robert Grenfell, said people should limit themselves to two standard drinks no more than five days of the week.
"However, in terms of heart protective effects, there are better ways to benefit from antioxidants than drinking wine. You are better off eating a diet high in fruit and vegetables," Grenfell said.