U.S. troops are carrying a heavier load than ever before, and it's not their gear weighing them down — it's their gut.

It takes muscle and mettle to serve in the U.S. Armed Forces — constant physical exertion, weeks of basic training — but more than half of the nation's military is overweight, according to a recent University of Wisconsin study.

The study, headed by Richard Atkinson, M.D., found that, "fifty-four percent of military personnel are overweight with more than twice as many men than women tipping the scales past the military guidelines."

The weight problem is highest in the Navy and lowest in the Marines, the study found.

The burgeoning waistlines prompted an order to the troops from the U.S. Surgeon General: shape up.

The Military Recommended Daily Allowance, based on the National Academy of Sciences/National Research Council Recommended Dietary Allowances for a healthier diet, was issued to help battle the bulge.

And at places like the Army Soldier Systems Center in Natick, Mass., the Armed Forces Recipe Service (AFRS) is working on the front lines of nutrition to trim the fat from soldiers' diets.

The team has spent years turning the standard military meat and potatoes recipes into dishes like Mexican turkey macaroni and vegetarian hearty burger.

Main dish entrees must total 10 grams of fat or less to be considered "low fat" and 10.1 to 15 grams of fat for "medium fat," according to criteria set by the AFRS Process Action Team.

"The Surgeon General mandated that we lower the salt, fat and cholesterol and that we increase complex carbohydrates and fiber," said Elizabeth Painter, a dietician with AFRS.

But these healthy meals don't replace burgers and fries in the dining hall, they're merely another option. So the true test of their success is if soldiers will actually eat them.

"Soldiers do have a choice — eat delicious greasy stuff or eat a salad," Army Maj. Pauline Geraci said in the military publication Star & Stripes. "What do you think they are going to choose?"

The dieticians admit they sometimes get soldiers into eating healthier by not labeling the food "low-fat."

"Our thrust is to stay on top of what's trendy in the restaurants so we keep the soldiers eating in the mess hall instead of going down the street," said Anthony Lee, a dietician with AFRS.

When asked if healthy food was a priority, Private Phuon Ngo of the U.S. Army echoed the sentiment of many troops: "It's not a concern in my mind really. I just want to eat whatever is good."

That doesn't surprise the cooks, who say they've designed the meals to please most palates. After all, this food has to feed an army.

Fox News' Amy C. Sims contributed to this report.