1500 calories and your activity level is closer to a weight loss calorie range. Increase to at least 2000 calories daily; maybe even more.
Do not use lowfat foods, use full fat. salad dressings, sour cream, cream cheese, cheese, cottage cheese, whole milk, etc. Make a rich smoothie or milkshake. Add butter, oil, margarine, gravy, cream sauces to veggies, potatoes, pasta, etc. You can use higher fat grains foods: biscuits, croissants, pasta dishes Add 1-2 more ounces to each meat serving Dietitian Becky
Figure out what your body would consume to maintain your weight based on the amount of activity you do. fitnessfrog.com and fat2fitradio.com have good calculators. Then, eat 100-200 calories over that. Continue to lift heavy in order to build some muscle. Eat plenty of protein, and don't be afraid of (good) fats.
First, congratulations and best wishes in your training. I know it can be tough. I was in the Reserves (Canadian).
Secondly, make sure you make your calories count. In other words, don't fill up on the empty calories, because you'll need the proteins and fats to take you through. That's not to say you won't need good long-lasting carbs, too - just not the empty ones in baked goods, for instance.
Other respondents have provided links, etc. that should also be helpful.
SparkPeople, SparkCoach, SparkPages, SparkPoints, SparkDiet, SparkAmerica, SparkRecipes, DailySpark, and other marks are trademarks of SparkPeople, Inc. All Rights Reserved.
SPARKPEOPLE is a registered trademark of SparkPeople, Inc. in the United States, European Union, Canada, and Australia. All rights reserved.