The Navy is the US military's fattest service branch, with an obesity rate of 22%, a new Department of Defense report found.

The Navy isn't the only service getting fat — obesity is on the rise across multiple services. The Air Force came in at 18.1%, the Army at 17.4% (the department's average), and the Marines at 8.3%.

Rising obesity rates in the military come amid rising rates in civilian society. Roughly 40% of American adults were considered obese in 2016, according to the Centers for Disease Control and Prevention.

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About one in five Navy sailors are obese, making it the US military's fattest service branch, a new Pentagon report found.

The obesity rate for the Navy was 22% — higher than the Department of Defense average — the "Medical Surveillance Monthly Report" said, adding that obesity is a "growing health concern among Sailors."

The report stressed that obesity affected Navy readiness — but this branch of the military wasn't the only one facing higher obesity rates. The Army came in at 17.4%, the Department of Defense average, while the Air Force had a slightly higher rate, at 18.1%. The Marines were by far the leanest, with an obesity rate of only 8.3%. Data was not available for the Coast Guard.

These calculations were based on body mass index, "calculated utilizing the latest height and weight record in a given year," the report said. "BMI measurements less than 12 and greater than 45 were considered erroneous and excluded."

The report did explain some limits to using BMI: that "Service members with higher lean body mass may be misclassified as obese based on their BMI," that "not all Service members had a height or weight measurement available in the Vitals data each year," and that "BMI measures should be interpreted with caution, as some of them can be based on self-reported height and weight."

Among the services, the report found, obesity rates were higher among men than women, as well as among people 35 and over as opposed to those in their 20s.

"The overall prevalence of obesity has increased steadily since 2014," it said.

Obesity is on the rise across the services, The New York Times reported. It said the Navy's obesity rate had increased sixfold since 2011, while the rates for the other services had more than doubled.

This trend appears linked to one in civilian society — 39.8 percent of adult Americans were considered obese in 2016, according to the Centers for Disease Control and Prevention.

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Roughly 30% of Americans between the 17 and 24 are ineligible for Army recruitment, and about a third of prospective recruits are disqualified based on their weight, Army Times reported in October.

"Out of all the reasons that we have future soldiers disqualify, the largest — 31 percent — is obesity," Maj. Gen. Frank Muth, the head of the Army Recruiting Command, told Army Times.

The Army's 2018 "Health of the Force" report said that "the high prevalence of obesity in the U.S. poses a serious challenge to recruiting and retaining healthy Soldiers."

The new Pentagon report further explained that "obesity negatively impacts physical performance and military readiness and is associated with long-term health problems such as hypertension, diabetes, coronary heart disease, stroke, cancer, and risk for all-cause mortality."