Question

How does the body convert a macronutrient into fat? Choose one.

Answer 1

Nutrients

A substance that provides nourishment for growth or metabolism.

are substances needed for growth, energy provision and other body functions. Macronutrients are those nutrients required in large amounts that provide the energy needed to maintain body functions and carry out the activities of daily life. There are 3 macronutrients – carbohydrates, proteins and fats.

Although each of these macronutrients supplies the energy needed to run body functions, the amount of energy that each provides varies.

Carbohydrates and proteins each provide 17kJ/g whereas fats provide 37kJ/g. 1 kilojoule (kJ) = 1000 joules.

4.2 joules is the energy needed to raise the temperature of 1g of water by 1°C.

Fats typically provide more than half of the body's energy needs. Fat from food is broken down into fatty acids, which can travel in the blood and be captured by hungry cells. Fatty acids that aren't needed right away are packaged in bundles called triglycerides and stored in fat cells, which have unlimited capacity.

Why do we need fats?

Although fats have received a bad reputation in relation to heart disease and weight gain, some fat in the diet is essential for health and wellbeing.

It is recommended that 20–35% of our daily energy requirement should be supplied through the consumption of fats and oils. In addition to supplying energy, fats are needed to:

• supply fatty acids that the body needs but cannot make (such as omega-3)
• assist with absorption of the fat-soluble vitamins A, D, E and K and carotenoids
• provide foods with flavour and texture.

Dietary fats are of 3 main types:

• Saturated fat – found in foods like meat, butter and cream (animal sources).
• Unsaturated fat – found in foods like olive oil, avocados, nuts and canola oil (plant sources)
• Trans fats – found in commercially produced baked goods, snack foods, fast foods and some margarines.

Replacing saturated fats and trans fats in the diet with unsaturated fats has been shown to decrease the risk of developing heart disease.