How many calories are needed to maintain or lose weight is based on many variables such as height, gender, age, current weight etc. so it's difficult to answer your question. If you really burn 700 calories during a workout then the intensity and duration is high. I'd start with 2500 calories, continue to work out and monitor your progress. If you aren't losing weight then reduce your daily calories by 500 and see what happens. You need to fuel your workouts with healthy eating and IMHO worry less about calories and more about a healthy life style. Good luck!