Fundamentals of Nutrition

What Are Macronutrients?

Macronutrients are the nutrients your body requires in large quantities to function properly. They provide energy and serve structural and functional roles in the body. The three primary macronutrients are carbohydrates, proteins, and fats.

Carbohydrates

Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen. They are your body's preferred energy source and play critical roles in various physiological functions. Carbohydrates are classified into different categories based on their chemical structure and how your body processes them.

• Simple Carbohydrates: Monosaccharides and disaccharides, quickly absorbed and providing rapid energy
• Complex Carbohydrates: Polysaccharides including starches and fiber, providing sustained energy and satiety
• Fiber: Non-digestible carbohydrates important for digestive health and metabolic function

Carbohydrates provide 4 kilocalories per gram of mass. Common sources include grains, legumes, fruits, vegetables, and dairy products.

Proteins

Proteins are made up of amino acids linked together in various combinations. Your body uses proteins to build and repair tissues, create enzymes and hormones, support immune function, and serve numerous other physiological roles. Of the 20 amino acids your body uses, 9 are considered essential—meaning your body cannot synthesize them and they must come from dietary sources.

• Complete Proteins: Containing all 9 essential amino acids
• Incomplete Proteins: Missing one or more essential amino acids
• Complementary Proteins: Incomplete proteins that, when combined, provide all essential amino acids

Proteins provide 4 kilocalories per gram. Sources include meat, fish, eggs, dairy, legumes, nuts, and seeds.

Fats

Dietary fats, also called lipids, are essential nutrients that serve critical functions in your body. They provide more than twice the energy per gram as carbohydrates or proteins, serve as precursors for hormones and signaling molecules, enable absorption of fat-soluble vitamins, and insulate organs and maintain body temperature.

• Saturated Fats: Solid at room temperature; found in animal products and some plant sources
• Unsaturated Fats: Liquid at room temperature; found in vegetable oils, nuts, and fish
• Essential Fatty Acids: Fats your body cannot synthesize and must obtain from diet (omega-3 and omega-6)

Fats provide 9 kilocalories per gram. Sources include oils, nuts, seeds, fish, and avocados.

Micronutrients: Vitamins and Minerals

Micronutrients are nutrients your body requires in smaller quantities but that are nonetheless essential for health. While they provide no calories, they enable virtually every biological process, from energy production to immune function to bone formation.

Vitamins

Vitamins are organic compounds necessary for your body to function. They are classified as either fat-soluble (vitamins A, D, E, K) or water-soluble (B vitamins and vitamin C). Each vitamin plays specific roles in physiological function, and deficiency can result in specific health conditions.

Minerals

Minerals are inorganic elements essential for various bodily functions including bone formation, nerve transmission, muscle contraction, and maintaining proper fluid balance. Key minerals include calcium, phosphorus, potassium, sodium, magnesium, iron, zinc, and others.

Caloric Density and Energy Balance

Calories are units of energy. Different macronutrients provide different amounts of energy per unit mass: carbohydrates and proteins provide 4 calories per gram, while fats provide 9 calories per gram. Understanding caloric content helps in comprehending how different foods contribute to overall energy intake.

Nutrient Density

Nutrient density refers to the concentration of micronutrients relative to caloric content. A nutrient-dense food provides substantial vitamins, minerals, and beneficial compounds relative to its caloric content. Whole foods such as vegetables, fruits, legumes, nuts, and fish tend to be more nutrient-dense than processed alternatives.

Hydration and Water

Water comprises approximately 60% of adult body weight and is essential for virtually every physiological function. It serves as a solvent for nutrients, maintains proper body temperature through perspiration, supports digestion, enables nutrient transport, and maintains proper fluid balance. Adequate hydration is foundational to health.