The pilot stated that he departed on a VFR flight and no flight plan was filed. He flew past his destination airport, reversed his course, descended down to 800 feet, and was in cruise flight when the engine lost power. An engine restart was not attempted and the pilot made a forced landing into the trees. The pilot stated that the airplane had not been registered with the FAA since he purchased it, and the condition inspection was expired. In addition, the pilot stated that he did not have a current flight review or medical certificate. The FAA examined the airplane and no anomalies were noted with the engine assembly and accessories, flight controls, or airframe. The fuel tanks were not ruptured and two ounces of fuel were drained from the lower fuselage fuel sump. Two gallons of fuel were drained from the main fuel tanks. The unusable fuel for the airplane is two gallons. The pilot stated to the NTSB that "he miscalculated his fuel burn rate which resulted in a total loss of engine power due to running out of gas."