From Task and Purpose :
Right now, 10.5% of all Army members are overweight, with the Air Force trailing close behind. The Navy is third, with the Marine Corps proving the most fit of all the branches with just 2.3% obesity. But it too has more than 4,800 members who exceed weight limits.
Overall, the military has an obesity rate of 7.8%, largely fueled by the Army’s 3.9% spike in obesity over the last five years.
Still, when compared to the overall population of the United States, obesity among service members is much lower. Data from the Centers for Disease Control  show that 68.8% of the adult American population is clinically overweight or obese.