Balanced Diet

Balanced Diet

Science 8

Learning objectives

• Students are able to define balanced diet

• Students are able to mention the factors that determine the nutrinional requirement of a person

• Students are able to discuss the composition of proteins, fats and carbohydrate in general to have balanced diets.

• Students are able to discuss malnutrition and its impacts

• Students are able to calculate the amount of energy obtained from the nutrient and calculate the amount of nutrient should be taken.

What is balanced diet?

• Balanced diet is a diet that contains right amount of all nutrients needed to make the cells in our body function properly.

• Balanced diet does not mean that there is equal amount of each nutrient.

Why balanced diet is important?

• Balanced diet provides right amount of nutrients needed for the cells to work properly

• Accordingly, balanced diet is very important to ensure our proper growth and health.

• We can get balanced diet by eating wide variety of foods

Multiple Choice

Balanced diet is

• When our diet contains same amount of all nutrients needed by our cells to function properly

• When our diet contains right amount of all nutrients needed by our cells to function properly

Multiple Choice

Which is the correct way to get balanced diet?

• Eat the food we used to eat

• Eat fancy foods

• Eat wide variety of foods

• Eat healthy food

What is the standard to know balanced diet?

• By knowing nutritional requirement, a person can know the foods he or she needs to get balanced diet.

• Nutritional requirement is the amount of various substances or nutrients in food needed by an organism (e.g. a person) to sustain a healthy life.

General nutritional requirements (proper compositions of nutrients)

• General rule: our diet must be able to replace energy we use and contains suitable mix of proteins, fats and carbohydrates

• The image on the right is one example of nutritional requirement

Multiple Choice

Among the six major nutrients we need to sustain our life, which one we need in highest amount than the others?

• Carbohydrate

• Proteins

• Water

• Fats

Go to this link to know your nutritional requirements for a day.

https://www.eatforhealth.gov.au/node/1813927/done?sid=573980

Factors that determine the nutritional requirements of a person

• Age

• Male or female

• Regions (colder area may need more energy (e.g. from fats or carbs) than warmer area

• Occupations and activities (e.g. athlete, officer worker, etc.)

• Other personal conditons (e.g. pregnancy and breasfeeding, allergies, recovery from certain disease, etc.)

Proteins

• Proteins is made of smaller components or molecules called amino acids.

• Some amino acids are able to be produced by the cells in our body. Some amino acids must be obtained from the foods we eat.

• The amino acids needed that the cells cannot produce are called essential amino acids.

Proteins

• There are 9 essential amino acids that we need to take from our foods. Four among them are histidine, leucine, lysine and valine.

• For a 10 - 13 years old teenager, about 34 gr/day of proteins is needed. It should come from variety of foods.

• We need to eat different variety of foods to get proteins so that we can get all the amino acids needed.

Fats

• Fats should make up 20 - 30% of our food.

• Fats provides twice energy per gram compared to carbohydrate.

• Foods that contain fats can also provide us with vitamins since some essential vitamins are soluble in fats instead of water.

• These are the vitamins that our cells cannot produce, so we need to get them from foods.

Fats

• Vitamins that soluble in fats are Vitamin A, Vitamin D, Vitamin E and Vitamin K.

• Fats and oil are giant molecules made from glycerol and fatty acids

Fats and oils

• Based on the types of fatty acid that make up the fats, fats can be classified as saturated fat (containing saturated fatty acids) and unsaturated fat (containing unsaturated fatty acids)

• Saturated fats give greater risk to heart disease so we need to minimize its consumption.

• Processed foods or instant foods are often high in saturated fats.

Fats and oils

• As mentioned above, fats are made from glycerol and fatty acids.

• Some fatty acids can be produced by our cells, some or not. So we need to get them from the foods. They are essential fatty acids.

• There are two essential fatty acids: omega-3 and omega-6 fatty acids. They are mostly found in fishes.

Carbohydrates

• 60% of energy we get from food should come from carbohydrates

• Carbohydrates provides quick supply of energy needed by the cells.

• Carbohydrates are made of smaller components or molecules. One of them is glucose

Multiple Choice

Which nutrient that we should get most from the food we eat?

• Fats

• Proteins

• Carbohydrate

• Vitamins

Multiple Choice

Which nutrient that produces energy the most per gram?

• proteins

• carbohydrate

• vitamin and mineral

• fats and oils

Multiple Choice

Which nutrient that plays the key role for building our muscles?

• carbohydrates

• fats and oils

• minerals

• proteins

Multiple Select

The reasons why we need to eat some amount of fats

• To store some energy to be used by the cells when needed.

• To build the tissue necessary to protect delicate organs

• To get the essential amino acids

• To get some essential vitamins

Multiple Select

The essential nutrients that we can get by consuming fishes

• Vitamin E

• Omega-3 fatty acid

• glucose

• essential amino acids

What is the condition when a person has imbalanced diet?

• When a person suffers from imbalanced diet this is called malnutrition

• Malnutrition is the condition when a person does not have balanced nutrition resulted from not enough intake of nutrients to meet the cells' need to function properly.

• The person cannot grow to their full potential height and easily suffer from health problems.

What is the condition when a person has imbalanced diet?

• Malnutrition is not necessarily always lacking of all nutrients, but also when nutrients are taken more than needed by the body.

• As the result the excess nutrients are stored as fats which can increase the risk of heart disease.

• Eating too much sugar like sweets and fizzy drinks can cause teeth decay. The sugar coats teeth and gum, increasing the growth of microbes. The microbes convert the sugar into acids that react with teeth.

How to calculate the amount of energy we get from a food

• Find information about the amount of nutrient contained in the food (e.g. 24 gr of fats, 45 gr of carbohydrate, etc.)

• Find the information about the amount of energy produced by one gram of the nutrient (e.g. one gram of carbohydrate produces 16 kilojoule of energy)

• Multiply the amount of nutrient contained in the food with the amount of energy produced by one gram of the nutrient.

Example:

Ana eats a chocolate ice cream. On the packaging it says that the ice cream contains 36 grams of sugar. One gram of sugar gives out 16 kilojoule of energy. How much energy that Ana gets from her ice cream.

Known: the amount of sugar in ice cream = 36 gr, the amount of energy produced by one gram of sugar = 16 kJ

Question: what is the energy Ana gets from the ice cream?

Answer: amount of nutrient x energy produced by one gram of nutrient =

 $36\ gr\ x\ 16\ \frac{kJ}{gr}=\ 576\ kJ$  

For calculating the amount of food we should eat in a day, we need to know:

• The amount of energy we need to get in a day. This is in Joule or kilojoule (kJ)

• The percentage of energy that we should get from certain nutrient (e.g. 60% of our energy in a day should come from carbohydrate)

• The amount of energy produced by one gram of the nutrient. This is in Joule/gr or kilojoule/gr (e.g. One gram of carbohydrate gives us 16 kilo Joule of energy)

How to calculate the amount of nutrient we need to eat:

• The amount of nutrient we should eat = (percentage of energy coming from the nuttrient x energy needed in one day)/energy produced by one gram of the nutrient

Example: As an athlete, Robert needs to take 10000 kilojoule of energy every day. 60% of his energy intake should come from carbohydrates. Carbohydrates release 16 kJ of energy per gram. How much carbohydrates should Robert take in a day?

Example:

Known: amount of energy needed in one day = 10000 kJ; percentage of energy that should come from carbohydrate = 60%; the amount of energy produced by one gram of carbohydrate = 16 kJ/gr

Answer:

The amount of carbohydrate should be taken in a day = (percentage of energy that should come from the nutrient x energy needed in one day)/energy produced by one gram of nutrient

Answer: 

 $\frac{\left(\frac{60}{100\ }x\ 10000\ kJ\right)}{16\ \frac{kJ}{gr}}=\ 375\ gr$  

How much energy can we get by consuming one pack of this snack?

According to FAO energy produced by the following nutrients are:

Fats = 37 kJ/gr

Proteins = 17 kJ/gr

Carbohydrates = 17 kJ/gr

Solution:

The amount of fats in the food = 10 gr.

The amount of energy from the fats = 10 gr x 37 kJ/gr = 370 kJ

The amount of carbohydrates in food = 13 gr.

The amount of energy from carbohydrates = 13 gr x 17 kJ/gr = 221 kJ

The amount of proteins in the food = 2 gr

The amount of energy from proteins = 2 gr x 17 kJ/gr = 34 kJ

Total energy obtained from the food = 370 kJ + 221 kJ + 34 kJ = 625 kJ