Energy - Factors Determining Energy Requirements

Definition

Energy in human nutrition refers to the power obtained from food to fuel bodily functions and physical activity.

Measurement

Energy is measured in kilocalories (kcal) or kilojoules (kJ), with 1 kcal equating approximately 4.184 kJ.

Factors Determining Energy Requirements

Age: Energy needs vary throughout life. Infants, children, and teenagers have higher energy requirements to support growth and development.

Gender: Males generally have higher energy needs than females due to larger muscle mass and differences in body composition.

Body Size and Composition: Larger body size and higher muscle mass increase energy requirements. Muscle tissue requires more energy than fat tissue.

Physical Activity Level: Active lifestyles raise energy needs. The more intense and frequent the physical activity, the higher the energy requirement.

Basal Metabolic Rate (BMR): The rate at which the body uses energy while at rest to maintain vital functions. It varies with age, gender, genetic predisposition, and body composition.

Thermic Effect of Food (TEF): The energy expended to digest, absorb, and metabolize food. It represents a small but significant portion of total energy expenditure.

Health Status: Certain health conditions and illnesses can alter energy requirements.

Energy Balance

Maintaining a balance between energy intake (from food and drinks) and energy expenditure (through BMR, physical activity, and TEF) is crucial for a healthy body weight.

• Positive Energy Balance: Occurs when energy intake exceeds expenditure, leading to weight gain.

Dietary Sources of Energy

Carbohydrates

Primary source of energy, especially for the brain and muscles during exercise.

Fats

Concentrated source of energy, providing essential fatty acids and aiding in the absorption of fat-soluble vitamins.

Proteins

Mainly used for growth, repair, and maintenance of body tissues, but can be an energy source when carbohydrate and fat intake is insufficient.

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