Basal Metabolic Rate (BMR) testing calculates the number of calories your body needs to maintain basic functions at rest, like breathing and digestion. This test typically uses indirect calorimetry, where you rest while a machine measures the gases you exhale to determine your calorie burn. Health benefits of BMR testing include more accurate calorie intake recommendations, better weight management, and optimized nutritional plans, making it ideal for individuals seeking to lose weight, gain muscle, or improve metabolism.