Dr. Carolyn Dean is a medical doctor and naturopath who has authored over 35 books. She explains that metabolism is the physiological process that breaks down food and converts it into energy to power the body's functions. A person's weight is determined by a combination of their calorie intake through food and drink and their physical activity level. The metabolic system mixes calories with oxygen to create energy. Even at rest, the body requires energy to perform essential processes like blood circulation, breathing, and cell repair and growth. A person's basal metabolic rate, the number of calories burned at rest, depends on factors like muscle mass, sex, age, and body composition. Additional factors that affect daily calorie burning are physical activity levels and