Your guide to macronutrients

Another day, another diet fad. Whether you’re trying to lose weight or just maintain a well-rounded diet, you’ve probably seen it all. One day the grocery store tabloids are shouting at you to avoid fats completely; the next day, carbs are the new evil. 

Of course, neither of those claims (or any related claim) is true. We need fats and carbs just as much as we need protein. These are all substances called macronutrients. 

You may have heard people talk about tracking or counting “macros”. What are macros, and why is everyone counting them?

Macronutrients, or “macros” for short, usually refer to the three main compounds your body gets from the foods you eat: carbohydrates, fats, and proteins. On the other hand, micronutrients are vitamins and minerals that your body needs, but in small amounts. 

Foods have varying amounts of macronutrients, but at least one is present in just about every bite. Understanding macros can help you develop a balanced diet. The U.S. Department of Agriculture (USDA) recommends that the average person get 10–35% of their daily calories from protein, 45–65% from carbohydrates, and 25–35% from fats (USDA, 2015). 

Carbohydrates, sometimes called "carbs" or “sugars,” play a vital role as fuel for your body. During digestion, carbohydrates get broken down into glucose. Glucose is a simple sugar and the primary source of energy for almost all of your body's cells and functions. Any extra carbohydrates that your body doesn't need get stored away as glycogen or fat for future use (Holesh, 2020). Carbohydrate is a generic term that includes sugar, grains, fruits, starchy vegetables, etc. You can break this category down into simple carbohydrates and complex carbohydrates.

Simple carbohydrates 

Simple carbohydrates contain one or two sugar molecules. They are a source of immediate energy and can raise blood sugar levels quickly—unfortunately, this may lead to a “sugar crash.” Also, some simple carbs (often called empty carbs) lack other nutrients and may lead to weight gain. Examples include table sugar, candy, and sugary drinks. However, simple carbs like those found in fruit and milk can be beneficial because the foods they come in also contain important vitamins and minerals, like vitamin C and calcium (AHA, 2018). 

Complex carbohydrates

Because of their complex chemical structure, these carbs take longer for your body to break down. This means that complex carbs don’t raise your blood sugar as quickly. Examples include starchy vegetables (like sweet potatoes), lentils, quinoa, broccoli, apples, spinach, and grains (rice, wheat, oats, etc.). 

Fiber is a specific type of complex carbohydrate that occurs naturally in whole grains, brown rice, seeds, legumes, etc. Whole grains have more fiber than refined carbohydrates (white rice, white bread, etc.) because they include the grains' outer shell, whereas refined grains have had most of the fiber removed to improve texture and shelf-life. Whole-grain fiber helps you feel fuller longer, which can help with weight loss if that's one of your goals. Also, diets rich in fiber can decrease your risk of diabetes, obesity, high cholesterol, and heart disease (AHA, 2018).

Fats, often cast as the villains of the food world, are vital for your body to function. Fats provide long-term energy storage for times of starvation or when food is scarce. They also help protect your organs, keep your body temperature stable, are a part of your cell membranes, and are needed to make hormones. Some important nutrients, like vitamin A, vitamin D, vitamin K, and vitamin E, are fat-soluble vitamins and need fats to be absorbed by the body. Certain fats, referred to as essential fatty acids, need to be consumed in food because your body cannot manufacture them (Calder, 2015). 

And let’s face it—fats make food taste delicious.

However, just because you need them does not mean that your body reacts to all fats the same way. You have probably heard about “bad fats” and “healthy fats”—in general, “bad fats” typically refer to saturated fats and trans fats, while “healthy fats” are unsaturated fats. And while it’s important not to demonize foods by labeling them as “good” or “bad," there are some things you need to understand about fats dubbed as “bad” and why it’s best to reach for unsaturated fats if you’re looking for a heart-healthy snack.

Saturated fats and trans fats

Because of their chemical structure, these types of fats tend to be solid at room temperature; think of butter, cheese, and lard. They also tend to come from animal products such as meat and dairy. Examples of foods high in saturated fats include fatty cuts of pork, beef, lamb, butter, cream, and cheese. Unlike saturated fats, which occur naturally, trans fats have been artificially processed to make food taste better and last longer on grocery shelves. 

Both trans fats and saturated fats increase your risk of developing high cholesterol, atherosclerosis (plaques in your arteries), and heart disease. And the American Heart Association (AHA) recommends that you avoid trans fats as part of a heart-healthy diet (AHA, 2017). Also known as “partially hydrogenated oils,” artificial trans fats are no longer  “generally recognized as safe” according to the Food and Drug Administration (FDA). The FDA has called for removing partially hydrogenated oils from processed foods (FDA, 2018). Foods with trans fats include margarine and many frozen pizzas, cookies, cakes, etc. 

Unsaturated fats

Unsaturated fats are better for you since they don’t increase cholesterol when used in moderation. Unsaturated fats are usually liquid (oils) at room temperature and come from plant or fatty fish sources. Sources of unsaturated fats include nuts, seeds, plant oils (olive oil, canola oil, etc.), fatty fish (salmon, tuna, sardines, etc.), and avocados. Unsaturated fats can be further classified into monounsaturated and polyunsaturated fats, depending on their chemical structure. 

Polyunsaturated fats include two essential fatty acids, omega-3 and omega-6 fatty acids; they are present in certain fish, seeds, and nuts (AHA, 2015). Omega-3 and omega-6 fatty acids have been shown to help lower cholesterol and may improve heart health, diabetes, inflammation, and several other conditions (Novotny, 2020). 

Proteins are essential, not just for building muscle mass, but for almost everything your body does; they make up hormones, enzymes, blood, skin, hair, parts of your nervous system, etc. In cases of very low carbohydrate intake, proteins can be converted into sugars and used as energy. Proteins are large molecules that your body breaks down into their amino acid building blocks. 

Building blocks of proteins include twenty different amino acids. Your body can make eleven amino acids on its own, but it must rely on food sources for the other nine—these nine are called essential amino acids (LaPelusa, 2020). 

Proteins may be considered complete or incomplete. Complete proteins provide all of the amino acids your body needs; examples include eggs, dairy, meat, seafood, and soy-based products. Incomplete proteins have some amino acids and come from plant sources like whole grains, nuts, legumes, and seeds (LaPelusa, 2020).

The short answer is no. 

Calories refer to the amount of energy that your body gets from the food that you eat. The more calories you eat, the more energy your body has to use. However, if you consume more than you use, your body stores the excess calories as fat, and you gain weight. 

Macros are the specific nutrients that your body needs and gets from all of the foods you eat: carbohydrates, fats, and protein. Each of these types of nutrients provides a specific number of calories, regardless of the kind of food (USDA, n.d.). 

• Carbohydrates: 4 calories per gram

• Protein: 4 calories per gram

• Fats: 9 calories per gram

A small brownie could have the same number of calories as a whole salad—but there is a difference in the breakdown of macronutrients and micronutrients, unsaturated fats vs. saturated and trans fats, protein, how full you feel afterward, etc. 

Therefore, when designing a balanced diet, you need to take both calories and macros into consideration. Your daily caloric intake will depend on your age, activity level, medical conditions, etc. Also, think about the recommended daily percentages of each of the macros. These can also vary by person to some extent, so you may want to consult a dietitian or nutritionist if you are unsure. 

Taking what you now know about macros, you can develop a weight-management plan that includes more than just a quantity of calories—you can focus on the quality of your daily calories.

There is no magic diet for weight loss or weight maintenance. The most effective way to lose weight is to take in less energy (i.e., calories) than your body uses, forcing it to burn off excess weight. And the most effective way to maintain your weight is to consume the same amount of energy that you burn.

Macros can help you design a balanced diet that provides necessary nutrients and keeps you fuller longer by including whole grains, fiber, proteins, unsaturated fats, etc. And don’t forget about exercise. Increasing your activity level will boost the number of calories your body uses per day and lead to more significant weight loss than just dieting alone.

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Current version

March 08, 2021

Written by

Chimene Richa, MD

Fact checked by

Steve Silvestro, MD

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About the medical reviewer

Steve Silvestro, MD, Ro

Dr. Steve Silvestro is a board-certified pediatrician and Associate Director, Clinical Content & Education at Ro.