Women typically find it harder to lose weight and inches than men. This, in part, is due to the fact that men have more lean muscle mass and a higher resting metabolic rate. Another issue that makes weigh loss challenging for females: women store fat differently from men--more of it goes to their thighs, buttocks, and hips, where it can be harder to shed. Finally, female hormones promote the storage of calories as fat, and fat takes up more space than muscle.
As the obesity rate keeps rising, especially among teenage girls, we need to press for more sex based research on exercise, diet, hormones and metabolism!