Essential Macronutrients

Carbohydrates

Carbohydrates are the primary source of energy for the body. They are broken down into glucose, which is used by cells for fuel and stored as glycogen in the liver and muscles.

• Definition: Organic compounds made up of carbon, hydrogen, and oxygen, providing energy for bodily functions.

• Types:

  • Simple carbohydrates: Sugars found in fruits, dairy products, and sugary foods. Provide quick energy.

  • Complex carbohydrates: Starches and fibers found in grains, legumes, vegetables, and nuts. Provide sustained energy and aid digestion.

• Calorie Content: 4 kcal/gram

• Recommended Intake: 45–65% of daily calories

Complex Carbohydrates

• Starch: Energy storage in plants; digestible by humans.

• Fiber: Part of plant cell walls; not digestible by humans.

• Water-soluble fiber: Dissolves in water; helps lower cholesterol.

• Insoluble fiber: Promotes digestive health; does not dissolve in water.

Example: Whole grains, fruits, and vegetables are excellent sources of complex carbohydrates and fiber.

Proteins

Proteins are essential for building and repairing tissues, including muscles, bones, and skin. They are made up of amino acids.

• Definition: Large molecules composed of chains of amino acids.

• Types:

  • Complete proteins: Contain all essential amino acids (e.g., meat, poultry, fish, eggs, dairy).

  • Incomplete proteins: Lack one or more essential amino acids (e.g., grains, legumes, vegetables, nuts).

• Calorie Content: 4 kcal/gram

• Recommended Intake: 10–35% of daily calories; 0.8 g/kg body weight per day for adults

Example: Combining rice and beans provides all essential amino acids, making a complete protein source for vegetarians.

Fats (Lipids)

Fats are a concentrated source of energy and are necessary for the absorption of fat-soluble vitamins and protection of organs.

• Definition: Organic compounds made up of fatty acids and glycerol; provide energy and support cell function.

• Types:

  • Saturated fats: Solid at room temperature; found in animal products; associated with increased risk of heart disease.

  • Unsaturated fats: Liquid at room temperature; found in plant oils, nuts, seeds, and fish; beneficial for heart health.

• Calorie Content: 9 kcal/gram

• Recommended Intake: 20–35% of daily calories; saturated fat < 10% of daily calories

Types of Unsaturated Fats

• Monounsaturated fats: One double bond in fatty acid chain (e.g., olive oil, canola oil, avocados).

• Polyunsaturated fats: Two or more double bonds (e.g., omega-3 and omega-6 fatty acids in fish, walnuts, flaxseed).

• Trans fats: Artificially created through hydrogenation; increase LDL (bad) cholesterol and decrease HDL (good) cholesterol; should be avoided.

Example: Salmon is high in polyunsaturated omega-3 fatty acids, which are beneficial for heart health.

Cholesterol

• LDL (Low-Density Lipoprotein): 'Bad' cholesterol; high levels increase risk of heart disease.

• HDL (High-Density Lipoprotein): 'Good' cholesterol; helps remove LDL from the bloodstream.

Water

Water is an essential macronutrient, making up 50–70% of the human body. It is vital for temperature regulation, nutrient transport, and waste elimination.

• Functions: Regulates body temperature, aids digestion, transports nutrients, removes waste.

• Sources: Beverages, fruits, and vegetables.

• Recommended Intake: 8–12 cups (2–3 liters) per day for adults.

• Dehydration: Can cause serious health risks, including impaired physical and cognitive performance.

Example: Drinking water after exercise helps restore fluid balance and prevent dehydration.

Summary Table: Macronutrient Calorie Content and Recommendations

Key Equations

• Protein Requirement:

• Energy from Macronutrients:

Additional Info

• Combining different plant-based protein sources (e.g., rice and beans) can provide all essential amino acids for vegetarians and vegans.

• High intake of saturated and trans fats is linked to increased risk of cardiovascular disease.

• Fiber is important for digestive health and can help regulate blood sugar levels.