Like all of Asia women are clustered in the 95-120lb range. Philippines is slightly chubbier than NE Asia (Japan/Korea). I don't believe in genetics, it's just time; their grandparents, and their parents, and they did not eat big mac meals w/ a super size coke. In a few generations they will probably be "big boned" like Americans.
They don't "work out", nobody in the Philippines can afford a gym membership.