Nutritional Glossary

Essential terms and concepts explained

Key Terms in Macronutrient Science

This glossary defines important terminology used in nutrition and macronutrient discussions.

Macronutrients

Amino Acids

Organic compounds that form the building blocks of proteins. The body uses 20 different amino acids; 9 are considered essential as they cannot be synthesized by the body.

Carbohydrates

Macronutrients composed of carbon, hydrogen, and oxygen. They serve as the primary energy source for the body and brain. Subdivided into simple and complex carbohydrates.

Dietary Fiber

Indigestible carbohydrate found primarily in plant foods. Fiber supports digestive health, helps regulate blood glucose levels, and promotes satiety.

Fats (Lipids)

Macronutrients composed of fatty acids and glycerol. Fats provide energy, support hormone production, and enable absorption of fat-soluble vitamins.

Glucose

A simple sugar that serves as the primary energy source for cells. Derived from carbohydrate digestion and maintained in the bloodstream to fuel various bodily functions.

Glycogen

The storage form of glucose in muscles and liver. When energy demands increase, glycogen is broken down to release glucose into the bloodstream.

Protein

Macronutrient composed of amino acids. Proteins serve structural, enzymatic, hormonal, and immune functions essential to human health.

Nutritional Concepts

Bioavailability

The proportion of ingested nutrient that is absorbed and available for physiological use. Factors like food preparation, combinations with other foods, and individual digestive capacity affect bioavailability.

Caloric Density

The amount of energy (calories) per unit weight of food. Fats provide 9 calories per gram, while proteins and carbohydrates provide 4 calories per gram.

Complete Protein

A protein source containing all 9 essential amino acids in sufficient quantities. Examples include meat, fish, eggs, and certain plant combinations.

Energy Expenditure

Total calories burned by the body through basal metabolism, physical activity, and thermic effects of food digestion.

Glycemic Index

A measure of how quickly foods containing carbohydrates raise blood glucose levels. Lower glycemic index foods provide more sustained energy.

Nutrient Density

The concentration of vitamins, minerals, and beneficial compounds relative to caloric content. Nutrient-dense foods provide substantial nutrition relative to their calorie content.

Thermic Effect

Energy required to digest, absorb, and process nutrients. Protein has a higher thermic effect than fats or carbohydrates, meaning more energy is spent processing it.

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