Resting metabolic rate (RMR) measures the number of calories the body expends while at complete rest, reflecting the energy required for essential physiological processes such as breathing, circulation, and cell production. RMR accounts for approximately 60-75% of daily caloric expenditure and is influenced by factors such as age, gender, muscle mass, and hormonal levels. Understanding RMR is essential for effective weight management strategies and can guide individuals in determining their caloric needs.