Suzy Favor Hamilton: Being an escort was "way better" than being an Olympian.

It all started with a cheeky threesome to celebrate her wedding anniversary.

You’d expect that not much could compare the thrill of competing at three Olympic Games. But for one athlete, being paid for sex gave her a much bigger high.

US track and field star Suzy Favor Hamilton, 47, says within six months she went from having a risqué threesome to celebrate her 20^th wedding anniversary to becoming “the most sought-after escort in Vegas”.

And the former escort says she still craves getting paid for sex like a drug, News Limited reports.

“I’d devoted myself to sex (and) my need to be unsurpassed in the bedroom had replaced the need to be best on the track,” she said in her soon to be released autobiography, Fast Girl – A Life Spent Running from Madness.

In an excerpt from the book, Favor Hamilton describes “the rush” she got from sex work.

“The appointment I’d just left was one of the fanciest hotel suites in Las Vegas. My body was still glowing with pleasure. This is way better than winning a race, I thought. This is better than competing in the Olympics. If I’d known how amazing this felt, I never would have wasted all that time,” she said.

“My old life with my parents and husband and daughter still waited for me in Wisconsin, but I went home less and less. I was Kelly now, one of the most sought-after escorts in Vegas. Suzy, the former professional athlete, the realtor, the wife, the mom — she had disappeared.

“Now that I’d devoted myself to sex, my need to be unsurpassed in the bedroom had replaced the need to be best on the track. But this was even better, because I’d hated the competition necessary to win a race. Everything about being an escort was enjoyable. I didn’t want to go back to my old life. Not ever.”

But there was an unhealthy side to her “extreme” change in occupation, Favor Hamilton said.

She said she entered a downward spiral and became suicidal following her collapse before the finish line during a race at the Sydney Olympic Games in 2000.

Her mental illness drove her to self-medicate and seek out risky behaviour.

The mother of one became a real estate agent and motivational speaker by day, and a high-priced escort by night – charging around AUD$800 per hour.

She said her husband agreed to her proposed fantasy life, unaware of her bipolar disorder.

“My bipolar was driven toward sex. It could have been driven towards drugs and alcohol, or gambling. I found sex was the biggest high to fuel my mania, which is common with bipolar people,” Favor Hamilton says.

But her secret double life, detailed in her autobiography, was ultimately exposed.

“I still crave that high,” she says.

“I can’t say I’ll never act out in that way again.”