101 Nutrition: Understand the basics of Food and Nutrition

Definitions

Nutrition
Nutrition is the process of consuming, absorbing, and using nutrients from food that are necessary for the growth, development, and maintenance of life (National Institute of Environmental Health Sciences, 2024).

It involves eating a healthy and balanced diet to provide the energy and nutrients your body needs to function properly and maintain health (MedlinePlus, 2021).  Proper nutrition supports energy levels, bodily functions, and helps protect against illness and disease (Harvard Health Publishing, 2023).

It involves several stages, including (Nutrition | Taber’s Medical Dictionary, 2025) : 

1. Consumption (ingestion)
2. Digestion
3. Absorption
4. Transport
5. Assimilation
6. Excretion of nutrients

Nutrients

Nutrients are chemical substances found in food that the body requires to perform basic functions, provide energy, build body structure, and regulate chemical processes (1.4: Overview of Nutrients and Calories, 2020). They are essential for maintaining health and must be obtained from the diet because the body cannot produce them all on its own (Green & Shallal, 2020). 

The six major classes of nutrients are (Morris & Mohiuddin, 2022): 

1. Carbohydrates
2. lipids (fats)
3. Proteins
4. Vitamins
5. Minerals
6. water

Calorie
A calorie is a unit of measurement for energy. 

In scientific terms, a “small” calorie (cal) is the amount of energy required to raise the temperature of one gram of water by one degree Celsius  (Osilla et al., 2022).

In nutrition, the term “calorie” usually refers to a “large” calorie or kilocalorie (kcal), which is the amount of energy needed to raise the temperature of one kilogram of water by one degree Celsius. One kilocalorie equals 1,000 small calories (Osilla et al., 2022). 

Calories in food represent the amount of energy the body can obtain from consuming that food (Scientists Say: Calorie, 2024).