Energy Requirement

• Energy

  • The energy stored within a food is only released when its bonds are broken down in the body during metabolism
  • This energy is used to fuel everyday activities, such as sending electrical impulses through the brain and nerves, moving muscles and synthesising body compounds
  • The amount of energy in food depends on the quantity of carbohydrates, proteins and lipids a food item contains
• Energy in Foods

  • Three nutrients supply energy (energy yielding): carbohydrates, proteins and lipids (measured in kJ) 
  • Vitamins & minerals do not provide energy to the body (not energy yielding) 
  • Most foods contain all three energy yielding nutrients, as well as water, vitamins and minerals
  • *Alcohol (Energy dense) Not considered a nutrient due to its diuretic nature as it depletes the body of its nutrients and interferes with the growth, maintenance and repair of the body. 
  • *Water is needed in large amounts but does not provide energy
  • 4.2kJ = 1 calorie (Americans still using calories) 
• Macronutrients and Energy Amount

  Carbohydrates = 16.7 kJ/g

  Lipids = 37.7 kJ/g

  Protein = 16.7 kJ/g

  Water = 0 kJ/g

  Alcohol = 29.3 kJ/g
• Acceptable Macronutrient Distribution Range (ADMR)

  • The percentages can then be compared to the Acceptable Macronutrient Distribution Range (AMDR) 
  • These ranges are recommended to ensure a balance of macronutrients to prevent the onset of diet-related disorders, whilst also allowing adequate intake of nutrients 
  • These ranges are set for healthy individuals who are maintaining their body weight and are not appropriate for weight loss or management of a specific health concern.
• Acceptable Macronutrient Distribution Range (ADMR)

  • AMDR recommends:

  15-25% of energy from protein 

  20-35% from lipids (<10% from saturated fats) 

  45-65% from carbohydrates
• Factors that Determine Energy Balance

  • We continuously expend energy and consume food periodically to refuel
  • An individual’s energy intake (energy in) should equal to their energy expenditure (energy out) to achieve an energy balance and maintenance of their weight
• Energy In

  A positive energy balance = energy intake is greater than energy expenditure 🡪 body fat/ weight gain 

  • Dependent on the composition of food (number of kilojoules) and the amount that is eaten. The amount of food consumed must
  • Meet the nutritional needs without taking in too much or too little energy
  • A person’s appetite prompts how much and how often to eat.
• Energy Out

  A negative energy balance = when energy intake is less than energy used 🡪 weight loss

  Energy expenditure is determined by:

  • Energy expended through basal metabolism (BMR)
  • Energy expended through physical activities
  • Energy expended through food digestion (thermic effect of food)
• Basal Metabolic Rate (BMR)

  • Basal metabolic is the rate at which the body expends energy for basal metabolic activities, which support all basic processes of life. 

  Basal metabolic… 

  • Maintains normal body temperature 
  • Maintains muscle tone
  • Keeps the heart beating and all vital organs functioning.
  • However, this rate varies from person to person
• Influences on BMR

  Body size 

  • Larger body sizes (including larger height) have greater metabolising tissue and larger surface area, increasing BMR 

  Growth

  • During childhood, adolescence and pregnancy energy demands are greater due to the growth experienced, increasing BMR

  Body composition

  • Lean body tissue increases BMR as muscle tissue is a faster metabolising tissue
• Influences on BMR

  Genetics/ Hormonal imbalances

  • can increase/ decrease due to influence at which the body expends energy.

  Illness/ infection

  • Increased BMR as the body works harder to build new tissues, develop an immune response and maintain normal body temperature

  Fasting, starving, dieting, malnutrition

  • Reduces BMR, because the body conserves energy to keep vital organs functioning (can lower by 15%)
• Influences on BMR

  Drugs

  • Caffeine and nicotine increase BMR
  • Anti-Depressants, steroids reduce BMR

  Exercise 

  • BMR increases during exercise + builds muscle tissue 

  Gender

  • Males have an elevated BMR than females due to muscle tissue
• Influences on BMR

  Climate/ Environmental temperature

  • Hot and Cold temperatures increase BMR as the body works harder to maintain normal body temperature.

  Age

  • Decreases with age due to less activity and reduce lean tissue
• Factors affecting Energy Expenditure (energy out)

  Physical activity 

  • Changeable 
  • During physical activity, muscles require greater energy to move, and the heart and lungs need additional energy to deliver nutrients and oxygen and dispose of wastes.
  • The amount of energy needed for any activity depends on muscle mass, body weight and activity.
  • The activity’s duration, frequency and intensity also influence energy expenditure
• Thermic Effect of Food

  • The energy required to eat and digest food, absorb nutrients, and move food through the gastrointestinal tract
  • Thermic effect is estimated at 10% of energy intake.
  • Higher for protein foods (20-30%) than carbohydrates (5-10%)  and lipids (0-5%) 
  • Also dependent on meal size and frequency
• Energy: Storage and  Balance

  • Storage of metabolised food is essential for times of famine and when the body requires great energy output.
  • Storage occurs in cells in the form of either glycogen or triglycerides. 
  • If the body’s energy needs are in balance, energy consumption equals energy expenditure.
• Energy Storage and Balance

  The body requires energy for:

  • Maintaining body temperature (heat energy)
  • Brain and nerve transmission (electrical)
  • Movement (mechanical)
  • Digestion and Metabolism (chemical energy)
  • The energy is easily transferred from one form to another depending on the body’s requirements.
• Energy Balance

  • Energy balance is defined as the state achieved when energy intake is equal to energy expenditure. When the body is in energy balance, body mass is maintained. Differences in energy balance can cause changes in the body’s mass.

  Energy Balance (maintenance of weight): Energy Intake = Energy Expenditure

  Positive Energy Balance (weight gain): Energy Intake > Energy Expenditure

  Negative Energy Balance (weight loss): Energy Intake < Energy Expenditure
• Nutrient Reference Values (NRV)


  Recommendations for healthy people that may not be appropriate for people with diseases that require an increase or decrease in nutrient needs
• Nutrient Reference Values (NRV)

  • Based on age, gender and specific life stages
  • Each person's body is unique and has its own set of requirements
  • Men differ from women and needs change as people grow from infancy to old age
• What the NRVs provide recommended intakes for

  • Energy (kilojoules)
  • Protein
  • Carbohydrate
  • Fibre
  • Fats
  • Water
  • Vitamins
  • Minerals
• The NRVs

  Made up of 5 different values
• Estimated Average Requirement (EAR)


  A daily nutrient level estimated to meet the requirements of half the healthy individuals in a particular life stage and gender group.
• Recommended Daily Intake (RDI)


  The average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97–98 per cent) healthy individuals in a particular life stage and gender group. Set higher than the EAR, to ensure needs are met.
• Adequate Intake (AI)


  Average amount of a nutrient that a group of healthy individuals consumes. This NRV is used when an RDI or EAR cannot be determined due to insufficient scientific evidence.
• Upper Intake Level (UL) 


  The UL is the point in which an individual exceeds the recommended intake and where a nutrient is likely to become toxic. Recommended to not exceed these recommendations.
• Estimated Energy Requirement (EER)


  The average dietary energy intake (kilojoules consumed per day) that will maintain an energy balance in a person who has a healthy body weight and level of physical activity.