The Definitions for Food and Nutritional Science

Definitions related to the science of the human body and nutrition

The terminology we so frequently use in human physiology and nutritional science is often inaccurate. Without a full understanding of the basics, how then can we fully conceptualise and determine what we need for our bodies optimal functionality and health? Here is a list of common terms used in nutritional science that you might like to reference for a better understanding.

Nutritional Science and Human Physiology Definitions – A simplified version.

What is energy?

Energy is the power one receives whether it comes from food and drink, electricity, fuel or other from which we produce motion or action. Energy can be physical or mental. It can also be directed toward an activity.

What is chemistry?

Chemistry is a particular branch of science. Chemistry deals with how we identify substances that are composed of matter. Chemistry is the study of these elements how they interact, change and combine with other substances.

If something is referred to as “chemical” this means how it relates to chemistry, how elements are developed, what they are made of, their reactions and the changes that they can go through. If something is a chemical, it is a substance that has the potential to undergo change through a series of processes. A chemical is not just a substance that is man-made though many think of a chemical in this way.

What is an Organism?

An organism is a single living thing. A person, plant or animal would all be considered an organism.

What is a cell?

A cell is the most basic unit of every living organism. Some living organisms exist in only one cell. Human beings contain trillions of cells. Cells are alive. Cells work to keep themselves alive. They produce energy, communicate within themselves, and they exchange information with neighbouring cells. Cells reproduce, and cells die.

What is tissue?

The tissue is material within the human body as well as present in animals and plants. Tissue encompasses a large number of cells, which are similar in form and function.

What is Muscle?

Muscles are masses of tissue found in the human body that are usually attached to bones. Muscle can tighten and relax (contract) to produce movement.

What is Fat?

Naturally oily or greasy in appearance, fat is extra flesh in the body that is found under the skin.

Some fats are vital nutrients that the body uses for building cells and fulfilling bodily functions.

What is an organ?

An organ represents something within an organism that is made of a group of 2+ tissues. These work together to accomplish a specific function necessary for sustaining life.

Muscle is considered to be an organ because muscle is comprised of only one kind of tissue. An organ must have at least two types of tissue for it to be defined as an organ.

What is a calorie?

A unit of measurement that shows how much energy can be produced by food. The potential energy stored in food.

Where extra calories are consumed beyond what the body requires, these will be stored as fat.

What is a nutrient?


A substance that gives a living body something that it requires continuing living and growing. Ie) water, fruit, vegetables