Balanced Diet and Carbohydrates

Study Notes

A balanced diet consists of seven food substances: carbohydrates, lipids, proteins, vitamins, minerals, fiber, and water.
Out of these, carbohydrates, lipids, and proteins are considered macronutrients, providing the majority of calories for the body.

Carbohydrates make up a small percentage of human body mass, only 1%.
They are the primary source of fuel for the body, providing energy by oxidizing glucose, a process known as cellular respiration.
Carbohydrates are categorized into two main types: simple carbohydrates and complex carbohydrates.

These are broken down quickly by the body for energy.
They are commonly referred to as “sugars”.
Simple carbohydrates are further divided into:
- Monosaccharides: single sugar molecules, such as glucose, fructose, and galactose.
- Disaccharides: two sugar molecules combined, such as sucrose, lactose, and maltose.
All carbohydrates are composed of three elements: carbon (C), hydrogen (H), and oxygen (O).

Complex carbohydrates are made up of long, complex chains of sugar molecules.
They are polymers, large molecules formed by repeating units called monomers.
Examples include starch and glycogen.
Starch is a large, insoluble molecule stored in plants, found in foods like rice, potatoes, and wheat.
Glycogen is the stored form of sugar in animals, found in the liver and muscles, where it can be quickly converted to glucose for energy.

Lipids, or fats, constitute about 10% of the body's mass.
Lipids are made up of the same three elements as carbohydrates: carbon, oxygen, and hydrogen, but in different proportions.
They have various functions:
- Essential structural components of cells.
- Insulation under the skin to prevent heat loss.
- Long-term energy storage.
- Protection of vital organs from mechanical damage.
Lipids can be solid or liquid at room temperature. Animal fats are typically solid, while plant oils are usually liquid.
The building blocks of lipids are glycerol and fatty acids. A molecule of glycerol combines with three fatty acids to form a lipid.
Saturated fats, common in animal fats, have no double bonds in their chemical structure.
Unsaturated fats, more common in plant oils, have double bonds in their chemical structure.

Proteins make up about 18% of the body's mass, second only to water (55-60%).
All cells contain proteins, which are crucial for:
- Growth and repair.
- Building and repairing tissues.
- Producing enzymes, hormones, and antibodies.
- Transporting substances within the body.
- Providing structural support.
Proteins are composed of amino acids, which are linked together by peptide bonds to form long chains.