Am I losing fat or muscle?

During school I lifted about 5 months for 4 days a week and now that school is out im not lifting as much anymore. I do push ups and other dumbbell workouts maybe 2-3 times a week now. I have also done some running maybe 2 times a week. Since school has been out for about a month now, I havent been eating those crappy fat filled school lunches anymore. Also, I am working at the local pool and tend to get small meals in the form of a packed lunch. Since school has been out, I have lost about 7-8 pounds. Ok heres the question, do you think this weight it muscle since I havent been lifting as intensly or just body fat from eating a little less and relativly more health food???