And with the clock ticking down on the military's Sept. 30 recruitment deadline for financial year 2010, the escalating number of overweight teens being turned away from recruitment centers has some military officials fearing for the future of the services.
"I know the importance of the people that serve in the military," said Lt. Gen. Norman Seip, a retired Air Force officer with more than 35 years of military experience. "It's not the weapons. It's not the high-tech equipment we put on someone's desk. It's the people."
The Centers for Disease Control and Prevention classify more than 34 percent of American adults age 20 and older as "obese" -- or having a body mass index higher than 30.
And up to 9 million Americans ages 17 to 24 -- or nearly 27 percent of the prime military recruiting age demographic -- are "too fat to serve in the military," according to an April study from Mission: Readiness, a non-profit group composed of senior retired military officials. The report cited obesity as the leading medical reason for candidates being deferred from the service, calling the epidemic "a potential threat to our national security."
According to the study, more than 140,000 individuals failed their military entrance physicals between 1995 and 2008 because of weight problems -- a 70 percent increase over that same period.
Through his military career, Seip has seen the nation's obesity numbers boom: In 1990, no state had an obesity rate of more than 15 percent, according to the Centers for Disease Control. But by 2009, only two areas -- Colorado and the District of Columbia -- boasted an obesity rate of less than 20 percent, while 33 states had rates greater than 25 percent and nine more had an obesity prevalence beyond 30 percent.
"It's taken us years to get to where we are [with the obesity epidemic], and it's gonna take years to get us back [to normal]," Siep said.
And with the military annually discharging more than 1,200 first-time enlistees before their contract expirations because of weight problems, according to the report, obesity imposes a hefty $60 million price tag for the military to recruit and train replacements.
"[Obesity] is a critical long-term challenge, for not only the military, but for the nation," said Dr. Curtis Gilroy, director of accession policy in the Office of the Under Secretary of Defense for Personnel and Readiness. "We're talking about national health here, which is a significant issue for this country."
In Philadelphia -- where obesity rates are "significantly higher" than the national average, according to an April Mission: Readiness study -- recruitment challenges extend beyond the waistline.
Staff Sgt. Terrence Garrett, who heads Army recruitment in the Philadelphia metro area, said that of the more than 1,000 of potential recruits he sees annually, about 75 percent do not meet military standards -- but it's not necessarily because of health problems.
"Ninety percent of the people that come in haven't been to jail, haven't been locked up. They've just been arrested, and that's on their record," Garrett told ABC News, adding that charges for drugs or violence can disqualify potential recruits from enlisting.
He also cited education as a major reason for turning away prospective recruits, estimating that only 20 to 30 percent of potential enlistees that he sees are able to pass the Armed Services Vocational Aptitude Battery (ASVAB), the military's SAT-like entrance examination that tests arithmetic reasoning, mathematics knowledge, paragraph comprehension and word knowledge.
In imposing both physical and "quality" standards -- including educational and aptitude benchmarks -- for all enlistees, the military is a "selective employer," and the standards are key to recruitment, Gilroy said.
"We call this an all-volunteer force, don't we? But it's really an all-recruited force," he told ABC News. "I think over the near term, [recruitment] is steady as she goes, if you will."
2009 was the first year since the 1973 formation of the all-volunteer force when all active and reserve components of the U.S. military -- including the Army, Navy, Air Force and Marine Corps -- met or exceeded their recruitment goals, both in terms of quantity and quality, according to the Department of Defense.
With recruits for both the active duty and reserve forces "slightly ahead" of their year-to-date goals, the military is on track to reach its 300,000-strong recruit benchmark for 2010, said Gilroy.
But while the numbers might seem re-assuring, many blame the economy for the enlistment boost, as more teens turn to a military career in the face of a tough job market.
"I think the key word there is 'for the first time.' It was the first time in history [for such record recruitment numbers]," said Amy Dawson Taggert, national director for Mission: Readiness. "A weak economy is no formula for staffing a strong military."
But for Seip and other military officers of generations past, the help can't come soon enough.
"That's our future," Seip said. "If we don't get that right, then bad on us, because we have no one else to blame but ourselves."