Apprentice adviser Nick Hewer has admitted that the candidates on the BBC1 series are "not the brightest business brains in Britain" and said that a former contestant might regret her decision "to take her clothes off at the drop of a hat".

This year's TV show began with 20 contestants competing to go into a business partnership with Lord Sugar.

Hewer told Radio Times magazine: "I'm not saying they are necessarily the brightest business brains in Britain, because the danger there would be that, first of all, those kind of people wouldn't have the confidence to withstand the white-hot heat of this process, and secondly that nine million people might not actually understand them."

He admitted that "ego, sometimes, is more valuable than talent" in the process of finding a winner and said that some of the candidates been distracted by fame.

"All of the candidates apply to be on the show for the right reasons - they want to work with Lord Sugar and start a business," Lord Sugar's right-hand mind said.

"But sometimes they get a little flattered by having cameras stuck in their faces, and then the thing airs, and they're walking down the street and cabbies are recognising them and then some agent gets onto them, thinking they can make a few quid, and before you know it, they think they're (Italian actress) Gina Lollobrigida!," he said.

"Take Luisa Zissman from last year, for example: she's actually a bright girl but decided to takes her clothes off at the drop of a hat, and that may be something she'll come to regret.

"Katie Hopkins has carved out a niche as a rent-a-right-wing-gob in the hope that by being nasty to everybody she'll find enduring fame. But who am I to judge? I hope they're very happy."

Meanwhile, Ben Fogle, who came to prominence on Castaway in 2000, said that reality TV had "lost its innocence".

"We all applied to be on that show for our own reasons, but the key was that no one did it to become famous. That's changed now. Most people who go on TV have another motive," he said.

"With something like 24 Hours ... I totally believe that it's an honest window into another world. But these days there's non-reality TV - either scripted reality or something like I'm a Celebrity..., which I've always seen as a show about egos rather than a genuine insight into an environment."