very confused person help needed!

bikini1234

Hello everyone a quick question I am on a 1300 calorie a day I am 5ft 4inches I am 21 and I am 188 pounds hoping to lose 50 pounds for august ok here is the question I still have no understanding of net calories, eating back calories or anything like that today I ran for 90 minutes non stop on a treadmill at a 6.7 speed mfp say I bured 1347 calories so consuming my daily 1300 cals mfp is reading that my net is 57 calories ?? Don't understand it or if its ok my routine will be run 4 days a week 90 mins each time lift weights twice a week for an hour and use stationary bike for an hour once a week so far I am fine with this I don't feel tired or lack of energy with 1300 cals but I was wondering if this sounds ok? Will I lose weight? Also I use to do a lot of running so I think that's why I can go long during workouts my body adjusts well to exercise. Also I don't eat exercise calories back mybe 20 at the most thankyou