Basal metabolism

Basal Metabolism is the rate at which energy is used by an organism at rest under neutral thermal conditions. The concept is closely related to the Basal Metabolic Rate (BMR), which is the amount of energy expended while at rest in a neutrally temperate environment.

Definition

The term basal metabolism refers to the metabolic activity necessary to maintain the basic physiological functions that sustain life, such as heartbeat, respiration, and maintenance of body temperature. This does not include the energy expended in physical activity or digestion of food.

Measurement

The measurement of basal metabolism is typically done through indirect calorimetry, which measures the amount of heat produced by an organism. This is usually done by measuring the amount of oxygen consumed and carbon dioxide produced. The Harris-Benedict equation is often used to estimate BMR in humans.

Factors affecting Basal Metabolism

Several factors can affect an individual's basal metabolism. These include age, sex, body composition, and thyroid hormone levels. For example, muscle tissue has a higher metabolic rate than fat tissue, so individuals with more muscle mass will have a higher BMR. Similarly, thyroid hormones can increase the metabolic rate by increasing the rate of cellular respiration.

Clinical significance

Understanding basal metabolism is important in the field of medicine, particularly in relation to conditions such as obesity, malnutrition, and thyroid disorders. For example, a low BMR may be indicative of hypothyroidism, while a high BMR may suggest hyperthyroidism.

See also

• Metabolism
• Thermogenesis
• Bioenergetics