© livestock & meat commission for northern ireland 2015 energy

© Livestock & Meat Commission for Northern Ireland 2015

Energy

Learning objectivesTo define energy and explain why it is needed.

To identify sources of energy in the diet.

To understand how energy needs change throughout the lifecycle.

To understand the energy needs of different levels of physical activity.

To define energy balance and understand the consequences of imbalance.


Energy

A regular supply of dietary energy is essential for life, and required to fuel many different body processes.

These include keeping the heart beating and organs functioning, maintenance of body temperature, muscle contraction and growth.

Daily energy requirements vary widely between individuals due to factors such as sex, body size, climate and physical activity levels.


Macronutrients

Energy is obtained by oxidation of macronutrients provided by the food and drink we consume.

Macronutrients are carbohydrate, fat, protein and alcohol.

The amount of energy that each of these macronutrients provides varies.


Energy provided by macronutrientsFat is the most energy dense nutrient:

• 9kcal/37kJ per gram

Protein provides less energy per gram: • 4kcal/17kJ per gram

Carbohydrate (starch and sugars) is the least energy dense nutrient:

• 3.75kcal/16kJ (a value of 4kcal/17kJ is used for food labelling purposes)

Alcohol also provides energy:• 7kcal/29kJ per gram


Units of measure

Energy intake is often measured in joules (J) or kilojoules (kJ), but many people are more familiar with Calories (kcal).

1 kilojoule (kJ) = 1,000 joules1 megajoule (MJ) = 1,000,000 joules1 kilocalorie (kcal) = 1,000 calories, or 1 Calorie

To convert from one unit to another:

1 kcal = 4.184 MJ so a 1000 kcal diet provides 4.184 MK or 4184 kJ

1 MJ = 239 kcal© Livestock & Meat Commission for Northern Ireland 2015

Energy in foods and drinks

Per gram, fat provides more than twice the energy of carbohydrate.


Carbohydrate Protein Alcohol Fat0

5

10

15

20

25

30

35

40

17 17

29

37

kJ

per

gra

m

Energy in food and drinks

Which of these foods do you think provides the most energy per 100g?


Olive oilTotal Energy: 3696 kJCarbohydrate 0.0 kJProtein 0.0 kJFat 3696 kJ

Wholemeal pitta breadTotal Energy: 1084 kJCarbohydrate 220.4 kJProtein 36.4 kJFat 105.3 kJ

HamTotal Energy: 451kJCarbohydrate 17 kJ Protein 73.6 kJFat 29.7 kJ

Dietary Reference Values

Average requirements for energy for different types of people have been estimated by experts, and are known as Estimated Average Requirements (EAR) for energy.

Experts have also recommend that:

• about 50% of our energy intake should come from carbohydrate;

• no more than 35% of our energy intake should come from fat;

• meaning around 15% of our energy intake should come from protein.


Dietary Reference Values

Energy requirements change throughout different life stages. Babies, young children and teenagers need proportionally more energy for their size to grow and be active.

After the age of 18 energy requirements decrease and remain the same until age 50, however actual needs depend on individuals activity levels.

For older adults, energy requirements decrease as activity levels fall, and there is a reduction in the basal metabolic rate.


EARs

SACN has also published new reference values for daily energy requirements as follows:

Children and teenagers


Breast-fed

Months Boys (MJ)Boys (kcal) Girls (MJ)

Girls (kcal)

1-2 2.2 526 2.0 4783-4 2.4 574 2.2 5265-6 2.5 598 2.3 550

7-12 2.9 694 2.7 646

Years Boys (MJ) Boys (kcal) Girls (MJ) Girls (kcal)1 3.2 765 3.0 7172 4.2 1004 3.9 9323 4.9 1171 4.5 10764 5.8 1386 5.4 12915 6.2 1482 5.7 13626 6.6 1577 6.2 14827 6.9 1649 6.4 15308 7.3 1745 6.8 16259 7.7 1840 7.2 1721

10 8.5 2032 8.1 193611 8.9 2127 8.5 203212 9.4 2247 8.8 210313 10.1 2414 9.3 222314 11.0 2629 9.8 234215 11.8 2820 10.0 239016 12.4 2964 10.1 241417 12.9 3083 10.3 246218 13.2 3155 10.3 2462

EARs

Adults

Why do you think there is a difference in requirements for males and females?

What effect would increasing activity levels have on the energy requirements?


Years Men (MJ) Men (kcal) Women (MJ) Women (kcal)

19-24 11.6 2772 9.1 2175

25-34 11.5 2749 9.1 2175

35-44 11.0 2629 8.8 2103

45-54 10.8 2581 8.8 2103

55-64 10.8 2581 8.7 2079

65-74 9.8 2342 8.0 1912

75+ 9.6 2294 7.7 1840

Basal metabolic rate

Basal metabolic rate (BMR) is the rate at which a person uses energy to maintain the basic functions of the body when at complete rest – including breathing, keeping warm, keeping the heart beating.

An average adult will use around 1.1kcal each minute just maintaining these functions.


Basal metabolic rate

BMR differs from one person to the next:

• infants and young children tend to have a proportionally high BMR for their size due to rapid growth and development

• Men usually have a higher BMR than women as they tend to have more muscle

• Older adults usually have a lower BMR than younger people as their muscle mass decreases with age.


Physical activity

In addition to their BMR, people also use energy for movement of all types, expressed as Physical Activity Level (PAL).

The amount of energy a person uses to perform daily tasks varies.


PAL

A PAL of 1.4 is associated with a low level of physical activity at work or during leisure time.

This applies to a large proportion of the UK population.

A PAL of 1.6 for women or 1.7 for men represents moderate intensity activity.

Values of 1.8 for women or 1.9 for men represent high levels of physical activity.


Physical activity

Physical activity should be an important component of our daily energy expenditure.

There are many different types of activity which can contribute to our total physical activity, all of which form an integral part of everyday life.

What do you think physical activity includes?• Activity at work, e.g. use the stairs not the

lift.• Household chores, e.g. vacuuming.• Looking after others.• Leisure-time activities, e.g. gardening.• Transport (walking or cycling to school or

work).• Sport.


How long do we need to be active for?The Department of Health recommends that in order to benefit health, children and young people should undertake at least 60 minutes of moderate intensity exercise every day.

Moderate intensity activity is defined as a level of activity that:

• leads to an increase in breathing rate;• leads to an increase in heart rate;• leads to a feeling of increased warmth.


How long do we need to be active for?It is also recommended that adults undertake at least 30 minutes of moderate intensity activity on 5 or more days a week.

What is ‘moderate intensity activity’ defined as?The activity does not have to be taken all at once – 3 brisk walks of 10 minutes each would be just as good.

These recommendations also apply to older adults. They should aim to maintain mobility through daily activities that promote and improve balance, strength and co-ordination.


Are we meeting the guidelines?Across the UK, average physical activity levels are lower than recommendations.

In Northern Ireland, only 60% of men and 47% of women meet activity recommendations.

It is estimated that less than 20% of children in Northern Ireland meet the recommendations for activity.


Body Mass Index (BMI)BMI can be used to identify if an adult is the correct weight for their height.

BMI can be calculated as follows:

BMI = weight (kg)/(height in m)2


Body Mass Index (BMI)Recommended BMI range (adults)

Less than 18.5 Underweight18.5 to 25 Desirable or healthy range25-30 Overweight30-35 Obese (Class I)35-40 Obese (Class II)Over 40 Morbidly or severely obese (Class III)

Apart from BMI, waist circumference is also a useful guide. Special growth charts are used for children.

Can you think of any examples where using BMI may not be a good measure of obesity?


Body Mass Index (BMI)

Calculate the BMI. Which BMI range would this go in?


AdeleHeight: 170cmWeight: 51kgTonyHeight: 1.95mWeight: 82kgGraceHeight: 1.63mWeight: 78kg

AdeleBMI = 17.6Range = underweightTonyBMI = 21.6Range = healthy weightGraceBMI = 29.4Range = overweight

Energy balanceIn order for people to maintain their body weight, their energy intake must equal their energy expenditure.

Energy balance can be maintained by regulating energy intake (through the diet), energy expenditure (adjusting physical activity level to match intake) or a combination of both.

When energy intake is higher than energy output, over time this will lead to weight gain (positive energy balance).

When energy intake is lower than energy output, over time this will lead to weight loss (negative energy balance).© Livestock & Meat Commission for Northern Ireland 2015

Positive energy balance

When the diet provides more energy than is needed to meet energy demands of the body, a person is said to be in ‘positive energy balance’.

This excess energy is stored as fat, which results in the person gaining weight over time.


Positive energy balance

If a positive energy balance is achieved over an extended period of time, a person is likely to become overweight or obese.

There are a number of risks associated with being overweight or obese, such as an increased risk of developing certain cancers, cardiovascular disease and type 2 diabetes.

If a large amount of weight/fat is stored around the waist that also increases the risk of these health problems.


Negative energy balance

When the diet provides insufficient energy to meet the energy demands of the body, a person is said to be in negative energy balance.

The energy the body requires is derived from energy stores and the person loses weight.

If a negative energy balance is achieved over an extended period of time, a person is likely to become underweight.

There are a number of health problems associated with being underweight, such as osteoporosis (low bone mass), infertility (difficulty to conceive) and even heart failure.


Energy balance

How can energy balance be maintained?

• Regulating energy intake through the diet

• Adjusting physical activity levels

• A combination of both


Energy balance

In the UK and many other developed countries, overweight and obesity rates in adults and children have been increasing over the years.

In 2013/14, almost a quarter of adults were obese (25%), with an additional 37% of overweight adults in Northern Ireland.

7% of children were obese, with a further 18% classed as overweight, so it is important to lead an active lifestyle and make healthy food choices.


Main sources of energy in Northern Ireland


Cereals and cereal productsMilk and milk products

Eggs and egg dishesFat spreads

Meat and meat productsFish and fish dishes

Vegetables and potatoesSavoury snacksNuts and seeds

FruitSugar, preserves and confectionary

Non-alcoholic beveragesAlcoholic beverages

Miscellaneous

0% 5% 10% 15% 20% 25% 30% 35%

30%9%

2%4%

19%2%

12%2%

1%3%

4%4%

5%3%

Sources of energy in the diet of Northern Irish adults

© livestock & meat commission for northern ireland 2015 energy

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