Ian Thorpe's newly trim physique created a buzz at a Sydney gala event this week, with fans quick to dream that the champion swimmer is in training for a comeback.

Thorpe, who spent the northern summer in LA, has shed about 15kg since last stepping into the limelight.

He has kept a low profile since returning to Sydney in November, the Daily Telegraph reports.

But when Confidential asked the man once dubbed Superfish if he was working towards a comeback at the age of 27, his eyes glazed over slightly as he responded with an emphatic, "No."

Thorpe is understood to have turned to boxing to tone up after he gained weight when he gave up his swimming training.