Now that the twins are out, Jennifer Lopez has reportedly turned her attention toward getting back to her fighting weight with the assistance of a personal trainer, which she recently flew out from California to her New York home with hubby Marc Anthony.

The National Enquirer is reporting that Beverly Hills-based fitness guru Gunnar Peterson was hired to develop a workout regime for Lopez, who gave birth to twins Max and Emme about a month ago.

A source close to Peterson tells the tabloid: "She wants to lose the baby weight fast. She wants to trim at least 20 to 25 pounds right away. She put on almost 40 pounds when she was pregnant with the twins.      

"Jennifer called Gunnar and asked him to get on a plane as soon a possible to come to New York. He has Jennifer doing different high-cardio workout programs at her home gym for an hour to an hour and a half every day."