Stadnyk, 39, told The Associated Press he refused to be independently measured because he was tired of being in the public eye.
"If this title had given me more health or a few extra years, I would have taken it, but the opposite happened, I only wasted my nerve cells," he said.
"If I have to choose between prosperity and calm, I choose calm."
Kosen, 27, told reporters in London that he was looking forward to parlaying his newfound status into a chance at love.
"Up until now it's been really difficult to find a girlfriend," Kosen said through an interpreter. "I've never had one, they were usually scared of me. ... Hopefully now that I'm famous I'll be able to meet lots of girls. I'd like to get married."
Kosen is one of only 10 confirmed or reliably reported cases in which humans have grown past the eight foot (2.44 meter) mark, according to Guinness.
The record-keeping group said he grew into his outsize stature because tumor-related damage to his pituitary triggered the overproduction of growth hormones. The condition, known as "pituitary gigantism," also explains Kosen's enormous hands and feet, which measure 10.8 inches (27.5 centimeters) and 14.4 inches (36.5 centimeters) respectively.
The tumor was removed last year, so Kosen isn't expected to grow any further.
The part-time farmer, who uses crutches to stand, said there were disadvantages to being so tall.
"I can't fit into a normal car," he said. "I can't go shopping like normal people, I have to have things made specially and sometimes they aren't always as fashionable. The other thing is that ceilings are low and I have to bend down through doorways."
But he noted some advantages too, including the ability to see people coming from far away.
"The other thing is at home they use my height to change the light bulbs and hang the curtains, things like that."
Kosen's trip to the U.K. – his first outside Turkey – was organized by Guinness to publicize the release of its 2010 Guinness World Records book, this year's repertoire of weird and wonderful records.
Associated Press Writer Maria Danilova in Kiev, Ukraine contributed to this report.
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