The company, which also owns Mexican food chain Chiquitos, said like-for-like sales growth would be lower as the firm fears tough trading conditions will not ease in 2016.
“It has become apparent from much of the recent data from the retail sector and the wider economy that the trading environment for many consumer facing businesses has been tougher in recent months than it was earlier in 2015,” the company said.
A possible Brexit, National Living Wage implementation and global uncertainty are all extra issues the firm could face. Shares dropped around 13%, or 82p, to 555p.
However, the group said sales for the year to December was up around 8% on the year before, with like-for-like sales 1.5% ahead.
Full-year results, expected in March, are expected to show material growth in both earnings and cash flow versus the prior year, with profits towards the middle of the current range of market expectations, the company said.