Test Your Nutrition Knowledge

Nutritional Requirements and Daily Energy Expenditure

• Daily energy expenditure (DEE) varies based on weight and gender, with adult males at 12000 kJ and adult females at 9500 kJ.
• DEE is comprised of three components: basal metabolic rate (BMR), voluntary physical activity, and diet-induced thermogenesis (DIT).
• BMR refers to the basal energy required to maintain life and is estimated by calculating 30% of body weight for males and 20% for females.
• The major tissues contributing to BMR are skeletal muscle, central nervous system, liver, heart, and other tissues.
• Factors that affect BMR include body weight, thyroid hormones, adipose tissue, body temperature, pregnancy, and lactation.
• Voluntary physical activity is the energy required by skeletal and cardiac muscle and can be estimated by adding 30-100% of BMR, depending on activity level.
• DIT is the energy related to processing food and is estimated at 10% of the energy content of ingested food.
• Total daily energy expenditure is calculated by summing BMR, energy required for physical activity, and 10% of these values to reflect DIT.
• Nutritional requirements include macronutrients (carbohydrates, fats, and proteins) and micronutrients (vitamins and minerals).
• Recommended dietary allowances/amounts (RDA) are based on dietary reference values and estimated average requirements, which vary based on age, gender, pregnancy, and lactation.
• Fats are important to the diet because they provide 2.2 times greater energy than carbohydrates or proteins, help with absorption of fat-soluble vitamins, and serve as structural components of cell membranes.
• Protein requirements are based on amino acids, which are building blocks of proteins and necessary for normal body structure and function. Daily protein requirement is 35g, with positive nitrogen balance needed for growing children and pregnant women, and negative nitrogen balance occurring in starvation or tissue wasting diseases.