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ENERGY
© PDST Home Economics.
Energy
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Energy is the ability to do work
The amount of energy the body needs depends on a
variety of factors, including : age, size & body weight,
gender, levels of activity, occupation, climate,
pregnancy, & illness
Measuring Energy

Energy is measured in kilocalories (kcal) or kilojoules
(kJ)
Nutrient
Kcal/kJ
Protein
Carbohydrate
Fat
Alcohol
4kcal/17kJ
4kcal/17kJ
9kcal/37kJ
7kcal/29kJ
Factors affecting energy
requirements
1.
Age
Young people require more energy as they are growing rapidly & tend
to be very active. As people get older energy requirements decrease,
together with their BMR (Basal Metabolic Rate)
2.
Size & Body Weight
The larger the body, the more energy it needs
3.
Gender
Men have a higher proportion of muscle to fat compared to women,
therefore men require more energy
4.
Level of Activity
The more people active are, the more energy they need. Running
requires more energy than playing a computer game
Factors affecting energy
requirements
4.
Occupation
Sedentary work eg. Office work, requires less energy than
manual work eg. Construction cork
5.
Climate
More energy is needed in colder climates to maintain a
consistent body temperature
6.
Pregnancy
During pregnancy & lactation, women require more energy
Pregnancy: Energy needed for the developing foetus
Lactation: Energy needed for the production of breast milk
7.
Illness
During times of illness, different amounts of energy are
Kate Hehir
required, eg, less energy is needed
during convalescence
Role of Energy in the Body
Energy fulfils four main roles in the body
1.
Growth
2.
Physical Activity
3.
Generating Heat
4.
Basal Metabolic Rate
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Role of Energy in the Body cont.....
Growth
Energy is also required for growing by toddlers,
young children, adolescents & pregnant women
1.
2.
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Physical activity
Energy is required for all physical tasks, including
standing, walking and running
The more strenuous the physical activity, the more
energy required
3.
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4.
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Generating heat
To maintain the body temperature at 37˚C, energy is
required
This is known as thermogenesis
Basal Metabolic Rate (BMR)
The minimum amount of energy needed to keep
internal organs working and to maintain body
temperature
Each person’s BMR is determined by their:
- Body weight
- Age
- Gender
BMR is measured when a person is completely at
rest, twelve hours after eating
Energy Balance
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Energy balance is reached when :
energy intake = energy output
If energy intake is greater than energy output, this
means being overweight or obese
If energy intake is less than energy output, this means
being underweight
Empty kilocalories provide energy but do not supply
the body with any nutritional value, e.g. Soft drinks
Daily Energy Requirements Table: Refer to Textbook
Healthy Eating Guidelines
Textbook
Reference

Refer to
the 10
healthy
eating
guidelines
in your
text book
Formulation of Guidelines – How?
1.
2.
3.
Dietary practices of population
are surveyed
The findings are analysed by
nutritional experts
Areas that require attention are
highlighted and considered in
drawing up the list of guidelines
Current Healthy Guidelines
Food Pyramid
Refer to
Diagram in
your text book
Function of Healthy Eating Guidelines
 To improve the nutritional status of the Irish
diet
 To promote an active & energetic lifestyle
 To respond to growing concerns about
childhood & adult obesity
 To recommend a reduction in over-processed
foods
 To recommend an increase in fibre to prevent
disorders of the bowel
 To ensure that all food groups & servings are
met
Reference Terms
RDA: Recommend Dietary Allowance
LTI: Lowest Threshold Intake: the least amount of
nutrient requirements that are needed by the public
Function of RDA’s: RDA’s help to:
1.
Interpret food consumption records
2.
Evaluate the adequacy of food supplies in meeting
national nutritional needs
3.
Design nutritional information labels
4.
Develop new products in industry
5.
Provide nutritional information on labels
Dietary Reference Values (DRV)
Dietary Reference Terms (DRV): RNI, LRNI, EAR
 These comprise a series if estimates of the amount
of energy & nutrients needed by different groups of
people
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RNI: Reference nutrient intake
LRNI: Lower reference nutrient intake
EAR: Estimated average requirements
Food Composition Tables: Show the nutrient content of
different foods per 100g or of liquid & they also show
the energy value of foods. Refer to textbook to view
Tables
Dietary Requirements of Babies
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First 6 months babies are fed milk
Either breast milk or formulated milk – Development & growth
Breast milk contains all the nutrients a baby needs & is recognised as being the
best for babies
Advantages of Breast feeding

Breast milk contains antibodies that build up the baby’s resistance to diseases

Breast milk is always at the correct temperature
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There is no need to prepare bottles or buy formula, which saves on time &
eliminates cost

Breasts are sterile & do not need any preparation prior to feeding. Breast milk is
readily accessible

It promotes bonding between mother & child

Babies are likely to gain the correct amount of weight

A Breast-feeding mother can find it easier to lose excess baby weight
Reasons for not Breast feeding:
1. HIV positive 2. Use of illegal drugs
3. Use of prescribed drugs
Weaning
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Solid foods are introduced when the baby is between 4 & 6
months
Single-ingredient foods should be used(this gives time to notice
any reaction – allergies/intolerances
Infant cereals, pureed fruit & vegetables are the first foods
given to babies
Factors to consider when weaning
 No sugar or salt should be added
 A balanced of foods from the four major food groups is
recommended
 Never give babies tea or coffee
 Honey should also be avoided until the baby is one year old
 Avoid additives by using fresh homemade food
Dietary Requirements of Children
Children need a highly nutritious diet as they continue to grow &
develop
 Protein: This promotes growth & is found in meat, eggs & cheese
 Calcium & vitamin D: These help develop teeth & bones & are
found in dairy products, particularly milk & cheese
 Iron & Vitamin C: These promote general health & foods such as
fruit & vegetables are rich in these nutrients
 Energy: Children who are active need a high intake of energy foods
 Sugary sweets & snacks should be avoided in order to reduce the
risk of obesity & tooth decay
 Portion sizes should be relative, i.e. For a child small portion sizes
are key. It is also important that food is arranged attractively as
children, like adults, ‘eat with their eyes’
 Lunches should be well balanced, e.g. Sandwiches should have varied
fillings. Fruit & yoghurt should be included with a healthy drink
Dietary Requirements of
Adolescents
Adolescence is a time of continual development & change
 Protein: Needed for growth & is found in meat & fish
 Calcium & vitamin D: For healthy teeth & bones. Found in
milk & cheese
 Iron: Important for teenage girls as they begin
menstruation, which leads to a loss of iron from the body;
this in turn can lead to anaemia. They must, therefore,
ensure they include iron-rich foods in their diet. Eg. Red
meat & offal
 Vitamin C: Increases the absorption of iron. It is also an
important factor in the diet of teenagers, girls in particular.
Vitamin C is found in fresh fruit and vegetables
 Energy requirements depend on the teenager’s level of
activity. Very active teenagers require high-energy foods
 High fibre foods are a good alternative to sugary foods
Problems associated with eating
patterns of adolescents
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Eating disorders, such as anorexia nervosa & bulimia
nervosa
Missing meals
Eating a large amount of fast food & snacks
‘Faddy’ eating
High energy intake through snacks, etc. But low intake
of nutrients
Start of alcohol consumption
Poor diet can contribute to problems such as acne &
obesity
Dietary Requirements of Adults
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Protein: This is important to repair the body’s cells. Protein is
found in meat, fish & eggs
Fat: Polyunsaturated fats reduce the risks of coronary heart
disease. Polyunsaturated fats are obtained from oily fish
Carbohydrates: These are used to provide energy. Adults should
reduce refined carbohydrate & replace them with high-fibre
foods, e.g. Wholegrain bread
Vitamins: Vitamin B for the release of energy from food. Vitamin
C for the absorption of iron. Vitamin D for the absorption of
calcium (oily fish, milk)
Minerals: Iron for healthy blood & to prevent anaemia; calcium
for strong bones & healthy teeth (milk & cheese)
Water: Water is important to remain hydrated
Dietary Requirements of Adults
Special Considerations
 Smoking causes many diseases & it kills. Adults
should not smoke
 Adults should be aware of the damage alcohol can
inflict on their bodies & reduce their alcohol
consumption, or cut it out completely
 Adults should cut down on their salt intake to
prevent high blood pressure
Dietary Requirements of Elderly
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Protein: This is necessary for the repair of body cells. Protein-rich
foods include eggs, fish
Fat: This is necessary to provide energy. To maintain low cholesterol
& to reduce the risk of coronary heart disease, unsaturated fats
should be used, e.g. Oily fish, polyunsaturated butter
Carbohydrates: Necessary for energy
Fibre: For a healthy digestive system & to prevent constipation. Fibre
rich foods include wholegrain cereals, skins of fruits & vegetables
Vitamins: Vitamin C(fruit & vegetables) for iron absorption & the
healing of wounds. Vitamin A(liver, eggs, carrots) for healthy eyes &
skin. Vitamin D(milk, yoghurt) for the absorption of calcium
Minerals: Calcium(milk, cheese) for strong bones & to prevent
osteoporosis. Iron(offal, dark green vegetables) to prevent anaemia
Water: This is necessary to remain hydrated
Dietary Requirements of Elderly
Special Considerations
 Sugar intake should be reduced to prevent the onset of
diabetes mellitus
 Salt intake should be reduced to prevent high blood
pressure
 Spicy foods should be avoided to prevent indigestion
 Foods that are easily digestible, such as white fish,
eggs & milk, should constitute a sizeable portion of food
intake to compensate for the loss of any teeth(or use of
false teeth), which can make chewing food difficult
Dietary requirements of convalescents
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Protein: This is necessary for repair of body cells. Protein
foods include eggs, fish
Fat: The amount of fat being eaten should be reduced, as
there is less energy being used. Reduce saturated fat &
replace with polyunsaturated fat
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Carbohydrates: These are necessary for energy
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Fibre: This is needed to prevent constipation
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Vitamins: General vitamin intake for healing is advised
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Minerals (Calcium & iron): These are important to promote
recovery, e.g. To heal wounds & prevent anaemia. Milk, cheese,
eggs, offal & dark green vegetables should be included
Water: This is important to maintain hydration, as dehydration
during an illness is very common
Dietary requirements of convalescents
Special Considerations
 Small portions that are easy to eat are preferable
 Meals prepared in a hygienic environment (because of
an increased susceptibility) to illness
 Foods that are easy digestible, such as white fish,
eggs & milk, should constitute a sizeable portion of food
intake
Pregnant & Breast feeding Women
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Protein: Necessary for growth of new body cells
Fat: Essential fatty acids (oily fish, eggs, liver) are necessary for
a foetus’s nervous system
Carbohydrate: These are necessary for energy
Fibre: This is needed for a healthy digestive system & to prevent
constipation. Fibre-rich foods include wholemeal bread, pasta,
skins of fruit & vegetables
Vitamins: Vitamin B folic acid (fortified cereals, leafy green
vegetables) is necessary to prevent neural tube defects, such as
spina bifida, in foetuses. Vitamin C is important for the pregnant
woman’s absorption of iron. Vitamin D is important for the
pregnant woman’s absorption of calcium
Minerals: Calcium (dairy products) for strong bones & healthy
teeth. Iron for healthy blood & prevent anaemia in both mother
& baby
Water: This is necessary for hydration
Pregnant & Breast feeding Women
Special Considerations
 Extra energy is needed during pregnancy. This
should be obtained from healthy sources
 Salt intake should be reduced to prevent high blood
pressure & water retention (odema)
 Pregnant women should not smoke or drink alcohol
 Pregnant women should not eat raw eggs, cooked
chilled foods, cream cheese, shellfish, etc. To
prevent the risk of food poisoning, such as salmonella
& listeria. This could also lead to miscarriage