11 - balanced diet and energy budget

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Unit 1 Topic 1~Lifestyle, health and risk~

~balanced diet and energybudget~

Prepared by:Ilyanie Hj. Yaacob

Biology ~ A-Level.



Daily nutrients human beings need in order to grow and k eep

healthy :

Macronutrients:

~ Carbohydrates~ Proteins

~ Fats (lipids)

Micronutrients

~ Mineral salts

~ Vitamins

Water

Fiber

Ov er v iew

Food pyramid.





Food should provide appropriate amount of the six following

components:

1) Metabolic fuel.

From carbohydrates, lipids and/or protein provide energy.

2) Combined nitrogen.

Required for the building of proteins provided by proteins or amino

acids.3) water.

Significant part of diet is 70-90% of body consist of water.

B alance diet



4 ) Dietary fibres.

Work as bulk that stimulates food movement through the alimentary

canal.

5) Essential minerals.

Needed for the construction of body tissues and essential for

metabolic processes.

6) Vitamins.Needed as coenzymes, as well as antioxidants in the body.

B alance diet



Undernutrition :

A type of malnutrition caused by

inadequate food intake or the body's

inability to make use of needed nutrients.

not enough food, sufficient amino acids,

minerals and vitamin.

resistance to disease e.g.: kwashiorkor.

Im balance diet -undernutrition



Overnutrition.

A form of malnutrition in which

nutrients are oversupplied

relative to the amounts requiredfor normal growth, development,

and metabolism.

Excess food is stored as fat

may result in obesity.

Resistance to disease e.g.:

CHD, hypertension.

Im balance diet - o v ernutrition



UK s National guidelines for nutrition:

Clarify nutrients people need.

Clarify quantities of each nutrient.

However, actual values will differ between each individual:

different lifestyle, everyday activity, age.

G uidelines for nutrition



Estimated population based on:

Committee on Medical Aspects of Food Policy (CO MA).

Replaced by Scientific Advisory Committee on Nutrition (SACN).

COMA develop dietary reference values (DRVs) show the range of

requirements and appropriate intakes for a group within the

population.




Dietary reference values (DRVs) consists of:

Lower reference nutrient intake (LRNI).

The amount of a nutrient that is enough for only the small number of

people who have low requirements (2.5%). The majority need more.

Estimated average requirement (EAR).

The average requirement for a particular nutrient for energy. For a

group of people receiving adequate amounts, the range of intakes willvary around the EAR.




Reference nutrient intake (RNI)

An estimate of the levels of protein, vitamins and minerals that should

meet the needs of most of the group to which they apply. The RNI is

the amount of a nutrient that is enough to ensure that the needs of nearly all the group (97.5%) are being met. By definition, many within

the group will need less.




Requirements of different nutrients will differ throughout life:

e.g.: women with heavy menstrual period need more iron than others.

e.g.: men ages 15-18 need more protein than women at the same age

as they still growing and making new tissues like muscles.

Balance between energy-giving nutrients and other nutrients are also

important as it can affect the chance to develop diseases.




Pearson page 49




How energy is measured?

M easure m ent of energy





In calorimeter:

A known quantity of food is burned in pure oxygen.

The energy released is transferred to the surrounding water as heat.

The rising temperature of surrounding water is measured.

The amount of food energy is calculated using the fact that 4 .2 kJ of

heat energy increase 1 oC of 1 kg of water.




Amount of energy in each metabolic fuel:

Carbohydrate : 17.2 kJ/g.

Lipids : 38.5 kJ/g.

Proteins : 17.2 kJ/g.

SI unit of energy = kilocalories.

4 .2 kJ = 1 kilocalorie.




Basal metabolic rate ( BMR):

The minimum calorific requirement (the amount of energy) needed to

sustain life in a resting individual.

BMR reflects the energy needed if the person lies on a bed all day andnight.

Calories are burned by bodily processes such as respiration, the

pumping of blood around the body and maintenance of body

temperature.

B asal m etabolic rate



BMR is determined by various factors, as follows:

Genetics:

Some people are born with faster metabolisms; some with slower

metabolisms.

Gender:

Men have a greater muscle mass and a lower body fat percentage.

This means they have a higher basal metabolic rate.

Age:

BMR reduces with age. After 20 years, it drops about 2%/decade.




Weight.

The metabolic rate of obese women is 25% higher than the metabolic

rate of thin women.

Body fat percentage.

The lower your body fat percentage, the higher your BMR.




In normal circumstances, an individual s estimated average

requirement for energy (EAR) can be determined by multiplying the

BMR by the physical activity level (PAL).

If energy intake and requirements are the same = no weight lose orgain.

If energy intake and requirements are different = weight lose or

weight gain.

E sti m ated a v erage require m ent



Pearson page 51

E sti m ated a v erage require m ent



Quantification of the body to determined underweight , normal ,

overweight and obese can be done by using:

i) Body Mass Index.

ii) waist-to-hip-ratio.

M easure m ent of health



Body Mass Index.

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

Charts are different for adults and children.

BMI is a very limited tool as it does not consider the proportion of fat

and muscle in human body not a good predictor of CVDs.

B ody m ass index



Classification of BMI:

B ody m ass index



Underweight:

A person is considered underweight if his

or her BMI falls below 18.5 kg/m 2.

Underweight happened among people inthe developed countries may be due to

eating disorder (anorexia nervosa @

bulimia nervosa).

Lead to muscle wasting, heart

damage, amenorrhea, increase risk of

osteoporosis and complications

during pregnancy.

B ody m ass index



Overweight:A person is considered overweight if his

or her BMI falls above 25 kg/m 2.

Most prevalent in people of develop

countries.

Overweight and obese could increase the

probability to develop various disease

CVDs, hypertension, diabetes.Most people who become overweight

consumed too many energy-rich items in

their diet as compared to their

requirements.

B ody m ass index



However, in world population, the number of overweight people are

greater than the number who lack sufficient food.

B ody m ass index



Pearson page 53

B ody m ass index



Waist-to-hip-ratio.

Calculation of body shape.

More accurate indicator for CVDs than BMI.

Linked to the pattern of fat laid down in the body and the balance of

HDLs and LDLs in blood.

A ratio of over 0.8 in women and over 1.0 in men indicate an

increased risk of heart disease.

W aist-to-hip-ratio

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11 - balanced diet and energy budget