Obesity is causing challenges for American military recruitment and active duty personnel.

Nearly one third of Americans between ages 18 and 24 are too overweight to serve in the military, according to a report released this week by Mission: Readiness, a group of more than 500 retired military leaders. (Read the full report here.)

Currently, 12 percent of active duty service members are obese based on height and weight – an increase of 61 percent since 2002. The report said obesity is resulting in "serious problems" with injuries and dismissals.

Obesity in the military and their families is costing the defense budget more than $1.5 billion in health care spending and recruiting replacements for those who are too unfit to serve, the report said.

The military's Healthy Base Initiative has resulted in healthier food served at military bases, but the report admitted the military cannot reverse the nation's obesity epidemic on its own.

"We must turn the tide on the obesity epidemic by instilling good eating and exercise habits from an early age," retired U.S. Army General Larry Lust said in a statement. "Good nutrition starts at home, and parents play a central role in combating childhood obesity, but it’s critical to remember that children consume up to half of their daily calories while at school and out of sight of their parents."

The report includes state-by-state data from the Department of Defense showing the increasingly high proportion of young adults who are ineligible to join the military.