"Being cooped up in a space with nowhere to run and nowhere to hide takes its toll."
About 3.4m people tuned in late on Friday as yoga fanatic Sada Walkington, 27, was thrown out of the heavily guarded East London house, following a vote by viewers.
Sada, who had spent two weeks in the house where every occupant's move is shown live on the internet and broadcast in television highlights, said she was not upset to be condemned as the least popular flatmate.
Channel 4 received 214,000 calls from the public voting her out. The vote at 2030 BST was watched by 3.5m people, with 387,000 voting in total.
Personal reasons
At a news conference Sada said: "It's wonderful to be first out. I'm very happy about it. I've done my time in the Big Brother house and I was ready to come out.
"Being cooped up in a space with nowhere to run and nowhere to hide takes its toll."
She denied she had gone on the show to publicise her soon-to-be-published book about men, and said she had not been interested in the £70,000 prize for the last contestant to be evicted.
"I went into it for personal reasons, to have a unique experience," she said.
"I've never been in it for the money. I can put my hand on my heart and say that was not a factor at all."
'Very selfish'
The London-based writer also gave a diplomatic rundown of the nine people still in the house - who nominated her as one of two contestants they most wanted to get rid of.
Textile artist Nichola, 28, was "an explosion of creative energy", while former sex aid saleswoman Caroline, 37, - the other nominee for the push - is "Broadway-bound with a sense of humour that nearly kills me", Sada said.
Ex-trainee nun Anna, 29, "hit the nail on the head every time", she said, Mel B look-alike Mel, 26, was "going places", stockbroker Nicholas, 32, was "getting the most out of his Reiki" and builder Craig, 28, was "always smiling", she said.
Self-confessed sex addict Andrew, 24, was "artfully clever", she said, computer design consultant Thomas, 30, was "enjoying the experience of a new vista on life" and Millennium Dome host Darren, 22, is "missing his mum's cooking like nothing else".
Fellow flatmates described Sada as "very selfish", "me, me, me" and "bloody-minded".