After easing for three weeks in a row, food inflation inched up to 17.40 per cent for the week ended January 16. Food inflation, which was falling after touching the decade's high of about 20 per cent in December, has risen again, driven mainly by rising prices of eggs and vegetables. High food prices led to firming up of overall inflation too, which rose to 7.31 per cent in December from 4.78 per cent in November. The overall inflation was at sub-zero levels for 13 weeks till last September. Rising food inflation, analysts said, could force the central bank to increase cash reserve ratio (CRR), the portion of deposits that banks keep with the RBI, by 50 basis points in the third quarterly review of credit policy on Friday.