Carbohydrates, lipids and proteins make up the three macronutrients. You need to eat a lot of these macronutrients each day, and their requirement is higher than that of micronutrients, aka vitamins and minerals.
All macronutrients are organic compounds composed of carbon, hydrogen, oxygen and sometimes other elements. As potential calorie sources, they can be oxidized to produce ATP, the body's main source of energy, according to a 2010 report in Nature Education.
While there are similarities between carbohydrates, lipids and proteins, they do differ. For example, proteins and carbs are water-soluble, but most lipids are not, so lipids require some extra work for the body to process.
Sugars and starches are the main digestible carbohydrates, and they provide glucose for energy production. The body stores extra glucose as glycogen.
Glucose can fuel intense, short bursts of activity and it is also necessary for brain function. If your body doesn't have much glucose to burn, it turns to converting fats and protein into energy, according to LibreTexts.
Fiber is another type of carbohydrate — it doesn't provide energy but it helps keep the digestive system healthy, according to the Academy of Nutrition and Dietetics.
The two main dietary lipids are fats/oils and cholesterol. Lipids are also the major component of cell membranes and they help protect the organs.
Fats also store energy and become a reserve fuel source, per a May 2021 StatPearls report. If your cells don't get enough glucose, your body burns fat for energy instead — this process creates ketones, according to the U.S. National Library of Medicine (NLM).
Healthy lipids include unsaturated fats, like polyunsaturated fats and monounsaturated fats, which can help improve your blood cholesterol levels when eaten in moderation and used in place of unhealthy lipids such as saturated and trans fats, per the American Heart Association (AHA).
Cholesterol does not supply calories, but it is a building block of very important chemicals such as vitamin D.
Remember, both lips and carbohydrates play an important role in delivering energy to cells. When you eat carbs, they are quickly broken down into glucose, which fuels all muscle action. Carbohydrates can also be stored as glycogen in the muscles and liver for later use. Lipids are either stored in various fat cells throughout the body for later energy use or in the liver, per Oregon State University.
Protein is composed of building blocks called amino acids. Protein's primary function is to build and maintain body structures, such as muscle, bones and internal organs, and to synthesize important molecules such as antibodies, enzymes, neurotransmitters and various blood proteins, according to the NLM.
Protein can be used for energy, but it's not the body's preferred source (carbs are!). One similarity between carbohydrates and lipids is that while the body can convert protein to glucose, neither carbs nor lipids can be converted to protein.
What's more, lipids, carbohydrates and protein are similar in the way that if you eat too much of them, they can be stored as fat.
The Three Macros Work As a Team
Even though all of the macronutrients can supply energy, a balanced diet providing all three will help the macros to perform their unique functions.
And foods that provide macronutrients are also sources of important micronutrients as well.
The Institute of Medicine sets forth dietary standards called the Acceptable Macronutrient Distribution Ranges, which recommend that 45 percent to 65 percent of your total calorie intake comes from carbs, 20 percent to 35 percent from fat and 10 percent to 35 percent from protein.
Though flexible, these ranges help ensure you get enough of each macro daily.