Simmons said to be hiding out at home and avoiding undergoing surgery

Eccentric and outgoing fitness personality Richard Simmons, who was once famed for his attention-grabbing behavior, has not been seen in public for a year.

The 66-year-old fitness instructor who rose to prominence for his quirky weight-loss videos and TV appearances is now reported to be suffering from health issues.

According to his official website, Richard has helped 'millions of overweight men and women lose more than three million pounds' with his 65 fitness videos and nine books.

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Simmons pictured at a students' exercise symposium in 2004, wearing his trademark shorts and tank top. The eccentric entertainer hasn't been seen in public for almost a year

The eighties fitness guru (pictured left and right) claims to have helped Americans shed three million pounds

But there are concerns Simmons is hiding out at his home in a state of depression over some much-needed knee replacement surgery.

If the surgery is ignored, he may never be able to exercise again, TMZ reported.

A source said Simmons was terrified of the surgery and has avoided undergoing it for most of the year. MailOnline has requested comment from Mr Simmons' agent.

Since his 80s heyday Richard Simmons has constantly sought to regain his faded fame, and can be easily recognized in LA by his bushy hair and trademark exercise shorts and tank top.

In 2011, the fitness guru had Dancing With The Stars viewers talking about his seemingly slimmed down build whist appearing on the show to coach celebrity contestant Chaz Bono.

The 63-year-old's smaller frame sparked speculation that something was awry, and perhaps he might even be ill - though this speculation was later quashed by his agent.