The pilot reported that, about 3 hours en route, he realized that the airplane's fuel level was very low. He started to look for nearby airports to land, but the engine rpm dropped, and he realized the airplane was going to run out of fuel before making it to an alternate airport. He decided to land in a nearby field, but on final, the engine experienced a total power loss. Subsequently, during the off-airport landing, the airplane's nosewheel touched down first and broke off. The airplane then "teetered," and both wings struck the ground before the airplane came to rest. The airplane sustained substantial damage to both wings. The pilot reported that he departed with about 40 gallons of fuel. He added that he must have burned off more fuel during taxi and takeoff than he realized and, that if he had stopped for fuel earlier in the flight, the accident would not have happened. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.