Australian coffee and cafe chains have been put on notice for selling sugary muffins the size of soft balls.
Research released on Friday found cakes and muffins from popular coffee chains are around two-and-a-half times larger than supermarket versions and contain twice the kilojoules.
Concerned about obesity, accredited practising dietitian Stephanie Liang from the University of Sydney says cafe owners need to reduce the portion sizes of the popular treats.
"Regularly eating kilojoule-heavy discretionary foods and larger portion sizes are key factors contributing to Australia's obesity epidemic," she says.
"Cakes and muffins are commonly-enjoyed discretionary foods, and their portion sizes have blown out over the past decade."
A study, presented at the Dietitians Association of Australia National Conference in Sydney this week, compared the serving size weights and energy (kilojoule) contents of 467 cake and muffin products sold in four supermarkets and eight coffee chains in Australia.
It found the average serve size for coffee chain cake products was 148g, compared with supermarket cake products at 58g.
The average cafe cake serving contained an average 1,805KJ, compared to 915KJ in the supermarket cake.
Both exceeded the Australian Dietary Guidelines' standard serve for 'discretionary' or unhealthy foods at 600kJ.
"Australians need access to more appropriate, smaller portion sizes when eating out at coffee chains. This would help Australians to get a better picture of normal serving sizes of foods like cakes and muffins," said Ms Liang.
Ms Liang says a muffin should be no bigger than the size of a tennis ball.
Customers are also recommended to share a cake or muffin with a friend of family member and choose cakes without icing.