Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic functions while at rest, such as breathing, circulation, and cell production. It represents the energy required to keep your body alive and functioning, even when you are not doing any physical activity. BMR is influenced by several factors, including age, gender, weight, and muscle mass. Generally, individuals with more muscle mass have a higher BMR because muscle tissue burns more calories than fat tissue. Understanding your BMR can help in managing weight loss or weight gain goals effectively.