The pilot of the Piper PA-28-180 had been flying for about 3 hours 35 minutes when the engine began to lose power. The engine regained power momentarily, after the pilot switched fuel tanks; however, it subsequently lost all power, and the pilot performed a forced landing to trees. The airplane impacted 50-foot tall trees prior to striking the ground. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that both fuel tanks were damaged and neither fuel tank contained fuel. In addition, there was no evidence of a fuel spill at the accident site. The pilot reported that he had topped-off the airplane's fuel tanks, which had a total capacity of 44 gallons of usable fuel prior to the flight. He leaned the fuel mixture during the flight, and expected the airplane to have an endurance of 4.6 hours. The pilot reported 94 hours of total flight experience; which included about 13 hours in the same make and model as the accident airplane.