The FAA's old standard for average weight was 170 pounds, but the ASTM standard pilot weight used for LSA is 190 pounds. Playing a little loose with the precise definition of "average," half the population will weigh more than 190. Me, for example, and I'm not all that big by today's standards. Design for heavier pilots, as somebody else pointed out. Not that many pilots weigh 170 or less any more.