The best way to lose extra pounds long-term is to combine a calorie-reduced diet with a combination of strength training and high-intensity interval training. Reduce your daily caloric intake by 500 calories per day, cutting out high glycemic index carbs and building your meals around lean protein. Do a full-body strength training fitness routine two times per week. On three other alternate days, do high-intensity interval training, either by sprinting on a field or running on a treadmill.