Approximately 56 per cent of the secretive borrowers took out their loan to cover debts of between £20,000 and £50,000.
Paul Morrish, director of Abbey Loans, said: "Borrowing in secret especially large amounts is not advisable and we would encourage people to be open and honest about their finances.
"Talking about your financial situation with others can help so that you can be realistic about what is affordable."
Mr Morrish continued to advise people to compare loans across the whole market as different types of loans suit different circumstances.
People's motivations for borrowing the money varied, with covering debts being the most popular reason.
A further 15 per cent of respondents used the money for home improvements, while five per cent paid for a holiday.
Meanwhile, more research from Abbey showed that women are less "financially fit" than men.
A study conducted by the bank showed that women are more likely than men not to shop around for the most suitable financial products.
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