(Bloomberg) -- Bill Gross, the former manager of the world’s largest bond fund, said the U.S. Federal Reserve must be “very careful in their moves” and needs to see a nominal growth rate of 4 percent to 5 percent before raising interest rates.

All central banks have to be cautious, but the U.S. especially, because “they’re the first one to get off the dime,” the former chief investment officer of Pacific Investment Management Co. said in a Bloomberg Radio interview on Friday. “This is a highly levered economy buffered by structural headwinds,” said Gross, who left Newport Beach, California-based Pimco in September to join Janus Capital Group Inc.

Gross said a Labor Department report report showing payrolls advancing by more than forecast and revisions upward for November and December will help the Fed slowly and carefully raise rates this year. Sustained employment gains will probably help assure policy makers that the expansion is well-rooted and can withstand an increase in borrowing costs.