Cardio is better than weight training for weight loss because it burns more fat. When exercising in the 60-70% maximum heart rate range, the body uses fat as its primary fuel source, which is an easier output level than the 80-90% range needed for muscle building. Cardio also improves cardiovascular health by reducing the risk of heart disease and artery problems, which are leading causes of death in men. For more efficient weight loss and disease prevention, cardio provides the simplest method.