What Are Lipids?

Lipids' function in the body and related risks

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Lipids are fatty, waxy, or oily compounds that are essential to many body functions and serve as the building blocks for all living cells. Lipids help regulate hormones, transmit nerve impulses, cushion organs, and store energy in the form of body fat.

The three main types of lipids are phospholipids, sterols (including the different types of cholesterol), and triglycerides (which account for over 95% of lipids in food). Lipids are found in higher quantities in fried foods, animal fats, and dairy products like cream, butter, and cheese.

Though lipids are important to your health, consuming excessive amounts in food can lead to diseases like atherosclerosis ("hardening of the arteries"), hypertension (high blood pressure), and coronary artery disease.

This article describes the three main types of lipids and what each of them do. It also explains what happens when blood lipids are high and how healthcare providers can measure this with a lipid panel test.

Types of Lipids and Where They Are Found

The three main types of lipids are phospholipids, sterols, and triacylglycerols (also known as triglycerides).


Phospholipids make up the outer layer of cells in the bodies of animals and humans. They create a protective layer around the cells.

Most people do not have to worry about phospholipids. However, they can cause problems for people with a rare autoimmune disorder called antiphospholipid syndrome (APS). APS often happens in people with lupus—especially women.

A common name for APS is "sticky blood." That's a good description of what happens inside the body when these key lipids cannot do their jobs.

In people with APS, the proteins on phospholipids get attacked, and the protective layers are damaged. As APS attacks blood cells and vessels, it increases a person's risk for blood clots that can lead to heart attacks and strokes. APS also may lead to pregnancy complications.


Sterols are a kind of steroid. Steroids are a group of hormones the body makes using lipids.

You might have heard about plant sterols or phytosterols. These substances are found in foods and offer many health benefits. Phytosterols are similar to the main sterol in humans, called cholesterol.

Most of your body's cholesterol is produced in the liver and the intestines, and about 20% comes from our diet. Cholesterol is found in every cell in the body and takes part in many important body functions, like making hormones and vitamin D. Cholesterol is also key for making bile salts, the substances that help the body break down fat and absorb vitamins.

Since cholesterol is a fat, and is not water-soluble, it requires protein to carry it through the bloodstream. Cholesterol (and triglycerides) are transported through the bloodstream by particles consisting of lipids and proteins, called lipoproteins. There are several types of lipoproteins, but the two major ones are high-density lipoprotein (HDL) and low-density lipoprotein (LDL).

HDL is called “good” cholesterol because it absorbs cholesterol and brings it back to the liver. LDL is called “bad” cholesterol because it can build up in the blood vessels.


Triglycerides are the most common type of lipid in our body and come from fats and oils in our diet. Triglycerides are important because they give us energy.

The lipids we consume in our diet can be saturated or unsaturated fats. Saturated fats are solid at room temperature and are typically derived from animal products such as meat, butter, and cheese. Unsaturated fats are usually liquid at room temperature and are often, but not always, derived from plants.

While "lipids" and "fat" are sometimes used interchangeably, fat (a.k.a. fatty acids) is only one type of lipid.

Unsaturated fats have essential nutrients commonly knowns as omega-3 fatty acids and are found in foods like tuna, salmon, nuts, seeds, avocados, and leafy vegetables. These unsaturated fatty acids can help reduce inflammation, blood pressure, and triglycerides in the body. They also lower the risk of sudden death from a heart attack and prevent blood clots from forming.

Trans fats, or "partially hydrogenated oils," are artificially made to have a certain texture desired for processed foods. They also increase the shelf life of baked goods. Eating foods that contain trans fats can lead to high levels of LDL (bad) cholesterol and can lower your HDL (good) cholesterol.

So, what foods raise triglyceride levels? Actually, it is all of those extra calories we consume from food and drinks, especially from alcohol and carbohydrates, that end up stored in the form of triglycerides in our fat (adipose) tissue. Over time, if you aren't burning those extra calories, you can develop high triglycerides and excess fat storage that leads to various metabolic conditions such as obesity, insulin resistance, diabetes, and even acute pancreatitis.

Role of Lipids in the Body

Lipids have a range of functions, including:

  • Supporting cells and aiding in essential functions
  • Protecting nerve cells
  • Helping the body absorb certain vitamins
  • Helping produce hormones, including estrogen, testosterone, and cortisol
  • Energy storage (in the form of fat)
  • Structural component of the cells

Nervous System

Lipids are a very important part of your nervous system. One place you'll find lipids is in the fatty tissue sleeves that protect your nerve cells and increase the conduction of their impulses (myelin sheaths).

Vitamin Absorption

Lipids make it possible for the body to use vitamins. Lipids also help the body absorb fat-soluble vitamins A, D, E, and K.

Here are just a few reasons why your body needs these vitamins:

  • Vitamin A is needed for the health of your immune system, vision, and reproduction.
  • Vitamin D helps with immune health and bone strength.
  • Vitamin E boosts the immune system, helps prevent blood clots, and protects cells from unstable molecules that can cause disease (free radicals).
  • Vitamin K promotes bone health. It also allows you to heal safely from injuries by helping your body form blood clots.

Hormone Production

Lipids are needed for the production of certain hormones, including estrogen, testosterone, and cortisol. Here are a few important jobs that hormones have:

  • Key players in sexual development and reproduction
  • Help control the immune system and metabolism
  • Keep water and salt (sodium) levels in the body balanced
  • Control inflammation and promote healing
  • Regulate the body's stress response
  • Regulate circadian rhythms.

Risks Associated With High Lipids

Lipids are essential for your health. However, having too many of them can put you at a higher risk of medical conditions like liver disease and heart disease.

Cardiovascular disease is the leading cause of death in the United States. The World Health Organization (WHO) estimates that 17.9 million people worldwide die from cardiovascular disease each year.

A buildup of LDL cholesterol can clog the arteries (atherosclerosis). These 'clogs' can narrow the opening of the artery and lead to a heart attack or stroke. High LDL levels are linked to diets rich in saturated fats, such as fatty or processed meats, cream-based sauces, cheese, deep-fried foods, and processed foods.

In addition to following a good diet, you can help to control your level of LDL cholesterol by keeping an ideal weight, getting plenty of exercise, and not smoking. These same lifestyle choices can also help boost your HDL cholesterol, as can including plenty of fish, olive oil, vegetables, legumes, nuts and high-fiber fruits in your diet.

Lipid Panel Tests

Your healthcare provider may want you to have a lipid panel test as part of your routine annual physical. They might also want you to have the test if you are at risk for cardiovascular disease.

A lipid panel is also called a cholesterol test. It uses a blood sample to determine your total cholesterol levels (overall), LDL, HDL, and triglycerides. From these values, the lab will calculate your cholesterol ratio.

What Does a Lipid Test Measure?

Jessica Olah / Verywell

The results of your cholesterol test can help your provider determine your risk for cardiovascular disease, including heart attack or stroke.


The three types of lipids—phospholipids, sterols, and triglycerides—are needed for many essential functions in the body. They also offer many health benefits.

Triglycerides and cholesterol may pose health risks if your levels are too high. The foods that you eat can increase your "bad" LDL cholesterol, lower your "good" HDL cholesterol, and raise your triglycerides, which can lead to health consequences.

A Word From Verywell

If you're concerned about your lipid levels, talk to your healthcare provider. A lipid panel test will give you the information that you need to begin making lifestyle changes, like getting more exercise and changing your diet, to help lower your levels.

When you're looking at the results of your cholesterol test, remember that not all lipids are created equal. High levels of LDL pose a serious risk to your health, but higher levels of HDL can help get your cholesterol under control.

Frequently Asked Questions

  • Where do lipids come from?

    Most of the cholesterol in your body is produced by your liver. Triglycerides are mostly derived from your diet, and excess triglycerides are stored as fat. Your lifestyle choices, including diet, have a major influence on the production of cholesterol and triglycerides.

  • Why are lipids used in certain medicines and beauty products?

    Cosmetics and skincare manufacturers add lipids to products to improve skin moisturization, protection, and repair. Lipids are added to some drugs to make their effects last longer, improve how the drug is absorbed, or help the drug target a specific area of the body.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Tolu Ajiboye
Tolu Ajiboye is a health writer who works with medical, wellness, biotech, and other healthcare technology companies.