What is the best diet for getting healthy

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I am interested mainly in getting my cardio, endurance and strength up and not really much focus on losing wight. I am preparing for the military and basic training takes a lot of endurance and strength. I go to the gym 6 days a week. I do strength training on upper body on Mon and Thurs, Legs on Tues and Fri, and Core on Wed and Sat. I also do 30 min of cardio each of those days and I take Sundays off.


My biggest concern is what is going to give me the best results as far as gaining strength and endurance. Right now I am 265lbs, 6' tall, 30 yo Male and I am getting better each time I hit the gym but was wondering what is the best diet to go with.