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ENERGY© PDST Home Economics.
Energy
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
ProteinCarbohydrateFatAlcohol
4kcal/17kJ4kcal/17kJ9kcal/37kJ7kcal/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
Kate Hehir
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 required, eg, less energy is needed during convalescence
Factors affecting energy requirements
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
Role of Energy in the Body cont.....
1. Growth
Energy is also required for growing by toddlers,
young children, adolescents & pregnant women
2. 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. Generating heat To maintain the body temperature at 37˚C,
energy is required This is known as thermogenesis4. 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
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
Refer to the 10 healthy eating guidelines in your text book
1. Dietary practices of population are surveyed
2. The findings are analysed by nutritional experts
3. Areas that require attention are highlighted and considered in drawing up the list of guidelines
Textbook Reference
Formulation of Guidelines – How?
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
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
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 Contains antibodies that build up the baby’s resistance to diseases Correct temperature No need to prepare bottles or buy formula, which saves on time &
eliminates cost Sterile Promotes bonding between mother & child Babies are likely to gain the correct amount of weight 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
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
meat & dark green 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
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 Protein: - repair the body’s cells, found in meat, fish & eggs Fat: Polyunsaturated fats reduce the risks of coronary heart
disease e.g. oily fish Carbohydrates: - provide energy. 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 AdultsSpecial Considerations Smoking & alcohol both inrease the risk of CHD Reduce salt intake to prevent high blood
pressure
Dietary Requirements of Elderly
Protein: repair of body cells, found in eggs, fish Fat: Provides energy. To maintain low cholesterol & to reduce
the risk of coronary heart disease eat unsaturated fats e.g. Oily fish, polyunsaturated butter
Carbohydrates: Necessary for energy. Choose fibre rich e.g. wholegrain cereals, 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. 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
diabetes Salt intake should be reduced to prevent high
blood pressure Spicy foods should be avoided to prevent
indigestion Choose foods that are easily digestible, e.g.
white fish, eggs & milk.
Dietary requirements of convalescents
Protein: Repair of body cells e.g. eggs, fish Fat: Reduce saturated fat & replace with polyunsaturated
fat e.g vegetable oils Carbohydrates: Reduce as not using much energy Eat
high fibre foods to prevent constipation e.g. prunes Vitamins: Vitamin A in oily fish and liver good for healthy
skin and respiratory tract. 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 Protein: growth of new body cells Fat: Essential fatty acids (oily fish, eggs, liver) are necessary
for a foetus’s nervous system Carbohydrate: necessary for energy, choose high fibre
sourcesto prevent constipation e.g. wholemeal bread, pasta, fruit &
veg. Vitamins: Vitamin B folic acid (fortified cereals, leafy
green vegetables) necessary to prevent neural tube defects, such as spina bifida, in foetuses. Vitamin C- absorption of iron. Vitamin D- absorption of calcium
Minerals: Calcium (dairy products) for strong bones & healthy teeth. Iron for healthy blood & prevent anaemia in both mother & baby
Water: necessary for hydration
Pregnant & Breast feeding Women
Special Considerations Extra energy is needed during pregnancy, about
200 kcals Salt intake should be reduced to prevent high
blood pressure & water retention (odema) Do not smoke- low birth weight No Alcohol- can cause foetal alcohol syndrome Pregnant women should not eat raw eggs,
cooked chilled foods, soft cheese, shellfish, etc. To prevent the risk of food poisoning, such as salmonella & listeria. Can lead to miscarriage