I think it's sad too. He's had some injuries and had been sick, but I think the "letting himself go" is part of the bigger issue of figuring out what he wants in life.
It's hard to see him walk away from so much talent while he's still in his prime (I though this was the gist of the OP's comment), but he'd be worse off if he kept pushing himself to do something so demanding if he didn't find it rewarding.
Here's an article that came out in the Guardian when he retired in 2006.
Five-times Olympic champion Ian Thorpe put an end to days of speculation last night when he announced his immediate retirement from swimming.
Thorpe, 24, has not competed for two years after taking a break after the Athens Olympics. After suffering a series of illnesses and injuries, his plan was to return for next March's World Championships, but now it seems that he lacks the motivation to compete at the top level.
In a press conference broadcast across Australia, Thorpe kept his audience on tenterhooks for several minutes, outlining what has been on his mind in recent times before confirming his career was over. He stated that while his Los Angeles-based coach Milt Nelms had helped bring up his fitness levels, now was an appropriate time to focus on other aspects of his life.
"As I got fit, physically fit, my mind also got fit and I started asking a lot of questions," said a surprisingly upbeat Thorpe. "I started to look at myself, not just as a swimmer but as a person. Another way of looking at it, you can swim lap after lap, staring at a black line, and all of a sudden, you look up and see what's around. That's what it feels like to me. Ask more questions, ask what the relevance of swimming is in my life now.
"I know that it's different to what it was two years ago, five years ago and 10 years ago, and it was most definitely different to what it was 15 years ago. That begged another question - what would my life be like without swimming? It's a very dark question for me because swimming has provided a safety blanket for me, a security net for me. When I'm not certain about developing other sides of my life, I just fall back into swimming."
Thorpe, nicknamed 'the Thorpedo' and famed for his size 17 feet, was expected to use the conference to withdraw from the Australian Championships in Brisbane next month, but rumours had been building for a few days that he may also call an end to his 10-year international career.
"I really hoped that I wanted to swim half as much as other people wanted me to, and I also realise it would be dishonest to myself and dishonest to everyone else if I was to continue on that basis," he said. "It wouldn't be for me, it would be for everyone else. I wouldn't be fulfilling my own dreams, I would be fulfilling the dreams other people have for me."
The last time Thorpe competed in a major international event was in 2004 when he claimed two gold, one silver and one bronze medal in the Athens Olympic Games - the haul complementing the three gold and two silver he picked up at the Sydney Games.
When he was 14 years old, he became the youngest male to ever represent Australia and a year later became the youngest individual world champion following his victory in the 400metres freestyle at the 1998 World Championships in Perth.
"I was catapulted into the international limelight as a kid and my swimming career started a long time before that," he said. "You guys didn't see it but I saw it. It has continued since that and I'm most certain that everyone here has seen it and I've reached all the dizzying heights of the sport, I've had a tremendous amount of success that I never thought would happen. For all of that, I'm extremely appreciative."
Thorpe also holds the record as the only person to win six gold medals in one World Championships - 2001 at Fukuoka - and has a total of 11 world titles gold medals. He has broken 22 world records, is Australia's most decorated Olympian and currently holds world records in the 200m and 400m freestyle as well as being a member of the world record-holding 4x200m freestyle relay team.
Thorpe swam in the Commonwealth Games trials in December last year but was unable to compete in the Melbourne Games the following March due to glandular fever, and also then broke his hand in an accident at home soon after recovering from that illness. In 2002, he won six gold medals when the Commonwealth Games came to Manchester.
"I am more proud that I've ever been of all of those achievements now that I've stepped away from the sport and I'm not prioritising it," he said. "I'm also very proud of the decision I've made today.
"It's a decision that has been difficult, it would have been easier for me to follow the status quo, but I realise that there are things in my life that are more important to me and I have to pursue them now. They are the things that are going to make me a better person and allow me to continue to contribute to this country and to what I want to do in the future."
© Guardian News & Media 2008