Fernando Alonso's weight and fitness is back at the same levels as when he was at his peak.

That is the news from his physio Edoardo Bendinelli, as the former two-time world champion this week turned 39 ahead of his 2021 return to F1 with Renault.

Observers have noticed that the Spaniard is visibly thinner than when he quit Formula 1 at the end of 2018.

"In terms of weight and physical shape, he is back at the level of 2009 to 2011," Bendinelli told Marca sports newspaper.

Alonso agrees that his physical condition is "better than ever", even though he is now pushing 40.

"I used to play football in the morning, then tennis, then cycling and in the evening I went karting," he explained. "That is no longer possible which is why I train differently now.

"I refine the details and work on my weaknesses. I am better than ever."

Some have speculated that Alonso's visible weight loss might be linked with reports that he became ill earlier this year.

"I got tested for corona but did not have the virus," he said. "I lost some strength and appetite but in the meantime I am back at the (fitness) figures from years ago."

Bendinelli said the program Alonso has been following is similar to when he signed for Ferrari.

"We made a training schedule so that he would be as he was at his peak, as he was in 2010 when he went to Ferrari," he explained.

"We compared all the parameters of the past with those of today and have started with the goal of getting back to the level of ten years ago. He wants to have the body and the head to do what he wants with a car," Bendinelli added.

Alonso claims that sitting out Formula 1 for two years has been good for him.

"If you take two steps back and look at everything calmly, you appreciate things in a different way," he said. "I'm a much better driver now than when I left Formula 1.

"And my age? Nonsense. Speed is determined by the watch, not your age.

"Carlos Sainz dominated the Dakar and look at his age," Alonso added, referring to the 58-year-old rally legend.