Just workout and eat a well balanced diet.
Unless you’re overweight by military standards you’ll lose any additional body fat during training. So,
@LibraryLady makes a very good point.
But if you really want to do the food management thing: 40% carbs (fiberous, not processed), 30% protein, 30% friendly fats (medium chain triglycerides)...My Fitness Pal app is great for tracking this. It’s very good for cal in vs. cal out tracking.
@Cookie_ suggests a great diet. Can’t go wrong with whole foods
Caculate your BMR first and create a 500-1000 calorie deficit with exercise. At your age and for how much you’re training you might not be eating enough.
Take one day a week and eat whatever you want.
The chow hall is going to have anything from Chilimac to sausage biscuits and gravy, fruit, bread, milk, mini cereal boxes, eggs, grits...Just normal food. Eat it all, eat as much as you can, as fast as you can.
One time in the chow hall a Drill Sergeant intensely boomed at me “PRIVATE, WHY DO YOU EAT SO MUCH FUCKING FOOD?!!!” I replied with equal intensity. “DRILL SERGEANT, IT KEEPS MY PT UP!”...and it did. Perfect 300s. On my final OSUT APFT I blew it and hit 298, went overboard on sit-ups (116 in two minutes), made me fall a bit short in energy for other exercises.
So,eat,eat,eat to feed your body and brain. And give 100% and then some everyday.
The DSs will modify your diet if they think it is needed. But again, get to the table fast and eat FAST! Before the Drills start yelling “GET UP, GET OUT!!!