The channels have now been taken off the air and 229 employees, based in London, have been made redundant.
Will Wright and Allan Graham from KPMG’s Restructuring practice have been appointed as joint administrators.
Will Wright, partner at KPMG and joint administrator, said: “It is really disappointing, given the hard efforts of the company and the support of the majority of its creditors, that a satisfactory conclusion to the restructuring could not be reached. Despite the recent approval of a Company Voluntary Arrangement agreement with creditors, a significant and unexpected fall in sales over the course of the last month meant that the company was simply unable to continue to trade.
Launched in 2000 by former ITV Digital directors Ashley Faull and John Egan, Sit-up had been through a number of owners, including Virgin Media and Munich-based Aurelius, the company that owns Germany’s RTL Shop. In in December 2013 Sit-Up was acquired by restructuring specialists Tnui Capital.