EARTH CITY, Mo. -- This was the message from running back Steven Jackson upon reporting to St. Louis Rams camp: "234.8 LBS and 5.1% body fat. I'm ready, let the games begin."

Jackson, long a physical force, is continually seeking ways to fine-tune his body. This offseason was no different. He's down from 245 pounds last season into the 235-pound range after entering into a program testing for food sensitivity at the Central Institute for Human Performance in St. Louis.

The program included blood testing and a six-week fasting period during which Jackson gave up some of his favorite foods, including eggs, salmon, broccoli, pork, vanilla and guacamole.

"I took these foods away for six weeks and just really, really slimmed down," Jackson said as the Rams prepared for their first practice of camp. "My energy feels up, I feel alive."

Jackson is now slowly adding the forbidden foods back into his diet, testing to see if any negatively affect his well-being. So far, so good.

"I've been lucky," Jackson said.

Jackson is looking to extend his streak of seven consecutive seasons with at least 1,000 yards rushing.