Metabolism
Quick Definition
The sum of all chemical reactions in the body that convert food into energy and building blocks for growth and repair.
In-Depth Explanation
Metabolism encompasses all chemical reactions that occur within living organisms to maintain life. It includes catabolism (breaking down molecules for energy) and anabolism (building complex molecules from simpler ones).
Basal metabolic rate (BMR) -- the energy required for basic functions at rest -- accounts for 60-75% of daily caloric expenditure. BMR is influenced by age, sex, body composition, genetics, and hormonal factors. The thermic effect of food (digesting food) accounts for about 10%, and physical activity accounts for the remainder.
Common misconceptions include the idea of a permanently 'broken' metabolism. While metabolic adaptation occurs during prolonged calorie restriction, it is generally reversible. Strategies to support healthy metabolism include maintaining muscle mass through resistance training, eating adequate protein, staying hydrated, getting sufficient sleep, and managing stress.