Swimming champion Geoff Huegill has revealed he took drugs and suffered from depression when he retired from swimming after the 2004 Athens Olympics.

Free of the discipline of 4am starts, Huegill engaged in binge drinking and became so hooked on fatty food that he put on 45kg.

And without direction in his life, Huegill also had suicidal thoughts.

"My life from about 2005 to 2007, I experimented with many different things. I guess that's a story that's in my past," he told the Nine Network on Sunday.

"When you go through depression, and you go through those dark periods of your life ... have a lot of uncertainty ... you don't know what's right and what's wrong."

That uncertainty followed 16 years in the pool, which Huegill described as a "sheltered life".

"When I got to the end of my career, and released my passion and my focus wasn't in the pool, I started to look at everything else in the real world," he said.

"Being in that sheltered world, I guess I had to learn pretty fast what the real world was like."

Huegill, a Commonwealth Games butterfly champion, has written about his battles in his new book Be Your Best.

He credits his wife Sara, whom he met in 2007, with turning his life around.

The couple are expecting their first child.

The 32-year-old athlete, who has since returned to swimming and shed the weight gained from his party days, said television shows like Underbelly glamorised drug use.

"The glorification of shows like Underbelly only make it worse because the young kids of today think that's a glamorous world or the real world that we live in when ultimately, it's not," he said.