Macronutrients (often called macros) are the nutrients in food that your body needs to maintain proper function. The three macronutrients are carbohydrates, fats, and protein.

A healthy, well-rounded diet is comprised of all three macronutrients in a balance that works for you, as all three play different roles in keeping your body fueled and able to do what it needs, from physical activity to problem solving.

According to Lauren Chaunt, a certified nutrition specialist, “eating a balanced ratio of macronutrients is important, as it optimizes these roles in the body and provides us with balanced, sustainable energy.” So what does each macro do, and how much of each should you be eating?

Carbohydrates

Carbohydrates – or carbs – are your body’s main fuel source. Besides supplying energy for your muscles and central nervous system, carbs help break down some amino acids (the building blocks of protein) and support your digestive system in staying regular.

Fiber is a type of carb that isn’t broken down during digestion, and it’s one of the reasons that carbohydrates seem to keep us feeling fuller for longer. While fiber doesn’t give you energy, it does help facilitate waste removal and keeps your intestinal tract healthy.

But not all carbohydrates are created equal. Some are considered simple carbohydrates, while others are complex – what’s the difference?

Simple carbohydrates

Simple carbohydrates are made up of one or two sugar molecules, making them easy to digest and be absorbed into the bloodstream. They can be used right away for an instant energy boost, as they readily break down to glucose.

If they’re not needed for immediate use in the body, simple carbohydrates are converted and stored as glycogen (the stored form of glucose) for later use. “While they provide instant energy to the body,” explains Chaunt, “the boost is short lived and often results in fatigue.” Think about that classic sugar crash.

Simple carbohydrates are found in sweet foods such as fruit, milk and milk products, and honey as well as sugars added to processed foods, like high-fructose corn syrup.

Complex carbohydrates

Complex carbohydrates are made up of 10 or more sugar molecules, bonded together in a long chain. These chains take longer to digest because the sugar molecules must be broken down to be digested. This provides more sustainable energy to the body, since blood sugar rises gradually over time.

Complex carbohydrates include starches and fibers found in legumes, starchy vegetables, and whole grains.

Protein

Protein is essential to building and maintaining muscle mass. Protein is made up of building blocks called amino acids, which fall into nonessential and essential categories.

Nonessential amino acids are made by your body, while essential amino acids are obtained only through the foods we eat. Amino acids are used to build and repair muscle tissue and provide structure to your body’s cell membranes, organs, hair, skin, and nails. Amino acids also create some enzymes and hormones, like melatonin (the hormone that helps you fall and stay asleep) and thyroxine (the thyroid hormone).

When it comes to protein, the source matters. Processed meats are high in protein but also high in saturated fats. Protein is most commonly found in animal products like meat, eggs, and fish, but there are also many plant-based sources of protein ‒ like legumes and nuts.

Fat

Fat is often viewed in a negative light, but this macronutrient is just as essential as protein and carbs. Fats are a type of lipid, a category of molecules that don’t mix well with water. Fat allows your body to store energy, absorb and transport fat-soluble vitamins (vitamins A, D, E, and K), and helps maintain cell membrane integrity. Fat also helps fuel your brain (did you know that your brain is almost 60% fat?) as well as provides cushioning for your internal organs and keeps them protected.

Fat has a higher caloric value than carbs and protein do, meaning that you need less fat in your diet than the other two macronutrients. The fat in your diet can come from trans fats, saturated fats, and unsaturated fats.

Trans fats

Trans fats come from hydrogenated oils in processed foods like margarine, baked goods, and fried items. Red meat and dairy also contain small amounts of trans fats, but most come from processed foods.

Trans fats can raise your LDL (“bad”) cholesterol and lower your HDL (“good”) cholesterol levels. Trans fats can also increase your risk for cardiovascular disease, diabetes, obesity, heart attack, and stroke. They should be avoided as much as possible.

Saturated fats

Saturated fats are typically solid at room temperature – think butter, coconut oil, and cheese. Too much saturated fat in your diet can lead to the same issues that too much trans fat can, including heart disease.

Saturated fat is found mostly in animal sources with high fat content, like beef, lamb, pork, poultry with skin, lard, cream, butter, full-fat cheese, and other dairy products.

Unsaturated fats

Unsaturated fats are typically liquid at room temperature and, according to the Harvard T.H. Chan School of Public Health, are considered “beneficial fats because they can improve blood cholesterol levels, ease inflammation, stabilize heart rhythms, and play a number of other beneficial roles.” There are two kinds of unsaturated fats: polyunsaturated and monounsaturated.

Polyunsaturated fats aid muscle movement and blood clotting. Omega-3 fatty acids are a type of polyunsaturated fat and are good for heart health; sources include fish, flaxseed, soybeans, oysters, and walnuts.

Monounsaturated fats can help reduce “bad” cholesterol levels, lowering your risk of heart disease and stroke. These fats also provide nutrients to help develop and maintain your body’s cells. Some foods high in monounsaturated fats are peanut oil, olive oil, avocado, and most nuts and seeds.

What Is the Ideal Macronutrient Split?

“While the ideal or optimal macronutrient ratio depends on your bio-individual needs, the USDA recommends a ratio of 45% to 65% of your diet coming from carbohydrates, 20% to 35% from fat, and 10% to 35% from protein,” explains Chaunt.

Factors such as age, genetics, activity level, and overall health all play a role in determining what macro ratio is best for you. Chaunt adds: “While it is important to keep these factors in mind, it is also essential to obtain your macronutrients from good-quality sources, to optimize your bio-individual health and well-being.”

Macronutrients vs. micronutrients

Macronutrients are the building blocks for all foods, and micronutrients fill in any gaps left behind. Micronutrients are vitamins and minerals needed by the body in very small amounts, yet they’re essential for maintaining good health. Imbalances and deficiencies are more common than you may think ‒ iodine, vitamin A, and iron deficiencies impact people globally, and women and children are most likely to be affected.

In serious cases, micronutrient deficiencies can cause dangerous health conditions, but they most often lead to less noticeable reductions in energy level and mental clarity. This can lead to lower test scores for students, reduced work productivity for adults, and increased risk for contracting other diseases and developing health conditions.

The Bottom Line

Macronutrients are carbohydrates, fats, and proteins – the building blocks of all food. Macros provide energy to your body and support bodily functions, e.g., supplying and storing energy, building and maintaining muscle mass, and keeping your digestive system regular. If you’re interested in learning more about macros and your individual macronutrient needs, speak with your physician, dietitian, or nutritionist or work with a Health Coach to support you on your overall wellness journey.