Belly fat is mainly dependent on a healthy diet. Many people get caught up with fat/carb content but it is even more important to focus on sodium/sugar content. Your body requires a healthy amount of all of these but high intake of sugar and sodium will cause you to retain more water weight obviously counteracting your desire for stomach definition. Isolating muscle groups during weight training 4-5 times a weeks is actually far more effective than whole body training 3 times per week. Your body requires rest and youre body is going to get used to full body workouts since theyre is only so many different things you can do.
Losing weight is hardly about working out; however, muscle burns more calories than fat. Losing weight is 80% the diet and 20% exercise. You would want to do full body, bodyweight exercises three times a week. (full body, and bodyweight burns more calories because you are using more muscles. you want to choose 10 exercises to workout with for the workout and keep the reps around 12-15. As for diet, i am not a nutritionist but something you can do is make healthier substitutes for things like cookies. you could just try any diet while you are on this exercise program and will lose around one pound a week. also, instead of drinking juice, have an actual fruit, it will provide you with fiber and will make you feel more full. DON'T DRINK SODA or eat any empty calories.