A Complete Guide to Macronutrients for Fitness Beginners

You’ve probably heard a fitness or health enthusiast mention “macros” while scrolling social media—but what actually are they, and why are they important? 

Macros (short for macronutrients) refer to the three primary nutrients required by human bodies: carbohydrates, protein, and fats. While some people have pretty strong opinions regarding ideal macronutrient ratios (i.e. how much we need of each), the truth is, no macro is better than another. They’re all essential and perform functions vital for overall health and performance. 

Below, read up on the unique physiological roles of macronutrients, factors that influence how much you need (including how active you are), and nutritious foods from each macro category.  

What Are Macronutrients?

Macronutrients encompass three essential nutrients that the body requires in relatively large amounts on a daily basis: carbohydrates, proteins, and fats. These nutrients serve as a source of calories that give us energy, and they help maintain various systems and structures within the body. For example, carbs are an efficient generator of adenosine triphosphate (aka ADP, which gives us energy), proteins build muscle and immune cells, and fats help you absorb nutrients and create hormones—just to name a few key roles of macros. 

No healthy diet should eliminate or seriously restrict any macronutrient, unless followed under the supervision of an appropriate medical professional such as a registered dietitian. 

What's the Difference Between Macronutrients and Micronutrients?

Micronutrients include essential vitamins (A, D, E, K, C, and eight B vitamins) and minerals (e.g. magnesium, calcium, zinc, selenium, and potassium). Compared to macronutrients, they’re needed in much smaller quantities—typically measured in milligrams (mg), micrograms (mcg), or international units (IUs)—but they’re just as important for health.

Unlike macros, micronutrients don’t provide energy, but they do participate in countless chemical reactions crucial for maintaining life and optimizing health. Many serve as helper molecules that assist in the metabolism or breakdown of macros to supply the body with energy, amino acids, and other building blocks. Others support proper muscle contraction to power you through your workouts, regulate gene expression and thereby curb risk of disease, or act as antioxidants to neutralize reactive oxygen species (“free radicals”) that might otherwise promote inflammation, muscle soreness, and chronic disease. 

Why Are Macronutrients Important? 

Carbohydrates, protein, and fat all play vital roles in promoting good health and optimizing fitness. “The biggest misconception I see around macronutrients is the idea that one macro is somehow more or less important than the other,” says Desiree Nielsen, RD, a registered dietitian and the author of Eat More Plants and Good for Your Gut. “But the reality is that our body is designed to consume all three because they all provide energy and serve different metabolic functions.” Below, learn the unique roles of each macro.  

The Importance of Carbohydrates

Carbohydrates are the body’s (and brain’s) primary fuel source, explains registered dietitian Jessica Cording, RD, CDN. When you eat a carb-containing food such as oatmeal or a banana, the body breaks down those carbs into small, simple sugar molecules, including glucose, that go into your bloodstream and subsequently enter your cells. From there, cells can convert glucose into energy in the form of ATP to help power countless biological functions necessary for survival, such as nerve impulse transmission, muscle contraction, and protein synthesis. Excess glucose not used right away for energy may be stored as glycogen in your muscles and liver for later use, like during a workout. 

While fat and protein can also be used to produce ATP, the body is much more efficient at converting glucose to ATP. So when you’re performing more intense physical activities that require a lot of energy quickly—think things like resistance training, HIIT workouts, sprint intervals, and indoor cycling—glucose from carb-containing foods and stored glycogen is the body’s primary ATP or energy source. This is why nutrition experts often recommend having a pre-workout meal or snack that contains some carbs before intense sweat sessions. 

Additionally, if you’re doing twice-a-day workouts, training for a marathon or century ride, or regularly partaking in exhaustive strength training sessions, you’re more likely to deplete your glycogen stores—which can lead to muscle fatigue and poor performance during your next workout. In this case, a post-workout meal or snack containing some carbs can help replenish glycogen and set you up for success for your next bout of exercise.  

Interestingly, though, carbs are good for more than just energy—they can help you preserve and build muscle, too. “Carbohydrates are protein-sparing, which means that when we consume enough carbohydrate, it keeps the body from burning protein [from muscle and from dietary sources] for energy,” Nielsen says. This, in turn, helps the body maintain lean muscle mass and allows dietary protein to be used for muscle protein synthesis (MPS) and other important processes. 

While you don’t want excessive amounts of any macronutrient, nutrition experts say it’s not uncommon for people to hinder their fitness goals by going too low carb. “I’ve seen clients struggle to reach their fitness and weight goals when they’re working out very intensely and restricting carbohydrate,” Cording says. “Once they ease up a little on the intense exercise and are more intentional about rest and about eating high-quality complex carbs to support their workout routine, they start to see the results they’re after—and they tend to feel a lot better mentally, too!”

Not all carb-containing foods are created equal, though. In general, you want to focus on unrefined, minimally processed carb sources such as vegetables, fruits, whole grains, and legumes (and limit highly processed carbs like white bread, crackers, baked goods, and certain cereals). Those minimally processed carbs are naturally rich in fiber, a type of nondigestible carbohydrate shown to support balanced blood sugar, help keep you full, improve cholesterol levels, promote insulin sensitivity, lower blood pressure, and support a healthy gut microbiome—plus, they tend to be a great source of micronutrients and beneficial antioxidant compounds such as polyphenols and carotenoids.

The Importance of Protein

When you eat protein-rich foods like chicken breast, that protein is broken down into individual amino acids, which are absorbed into your circulation and used as “building blocks” to grow and repair every structure and tissue in the body—including skeletal muscle tissue; the collagen that makes up skin, bone, tendons, and cartilage; and the keratin that makes up hair, skin, and nails. So, adequate protein is necessary for building strength, preventing injury, and supporting a healthy outward appearance. 

Consuming enough protein is particularly important for optimizing MPS, or the process by which amino acids are incorporated into skeletal muscle proteins to build and repair muscle tissue. Eating enough protein can help preserve the muscle mass you already have while combining protein with resistance training can optimize MPS and help you build additional muscle mass. Having a healthy amount of muscle is not only key for boosting performance, but also for curbing risk of sarcopenia (age-related muscle loss), which is associated with poor mobility and early death. 

Muscle is also more metabolically active than fat, meaning you burn more calories—even at rest—when you have more muscle mass. Distributing protein intake throughout the day, as well as consuming a balanced snack that contains protein, carbs, and healthy fats after strenuous workouts, can also help optimize MPS and muscle gains. 

But protein can do a lot more than build muscle. For one, including adequate protein (and fat) in meals helps stabilize post-meal blood sugar levels. In addition to curbing diabetes risk, “blood sugar balance is really important for helping you stay full and supporting stable energy and mood,” Cording says. Amino acids from protein are also critical for supporting immune function, per Nielsen—for example, they’re needed to create white blood cells and antibodies to help ward off infections. Additionally, amino acids are an important component of enzymes, proteins that catalyze every chemical reaction in the body. 

Animal proteins like meat, fish, and dairy are often considered high-quality picks since they’re “complete proteins,” meaning they contain all nine essential amino acids that can’t be made by the human body. But don’t stress if you’re a plant-based eater: You can still get all essential amino acids by consuming a variety of plant foods (think: tofu, nuts, seeds, and beans). Plus, plant proteins are associated with enhanced longevity. Just aim to limit your protein intake from highly processed meats such as bacon, pepperoni, sausage, deli meats, and hot dogs, which are more strongly linked to cardiovascular disease and various cancers.

The Importance of Fats

While carbs and protein often get all the hype when it comes to eating for optimal fitness, fat is just as crucial for overall health and well-being. Like protein, one of the most immediately noticeable benefits of including fat in your meals is that it promotes stable blood sugar and helps keep you full, Cording says. Fats also aid in the absorption of fat-soluble compounds in our food, from the vitamins A, D, E, and K to carotenoid antioxidants and sterols (plant compounds with cholesterol-lowering properties). 

Once dietary fats are broken down into fatty acids and absorbed via the lymphatic system and bloodstream, fatty acids can serve as a structural component of cells, building blocks of signaling molecules, and a concentrated source of energy (a gram of fat provides 9 calories, while a gram of carb or protein provides 4). “Fatty acids are incorporated into our cell linings, influencing both how flexible these cell linings are and the way they communicate with each other,” Nielsen says. “They are also used to build signaling molecules in the body like prostaglandins,” which play key roles in healing, blood flow, inflammatory response, menstruation, ovulation, and more.

Fatty acids (from dietary fat or stored body fat) are also used to produce steroid hormones, including testosterone, estrogen, and progesterone. A 2021 meta-analysis of studies found that low-fat diets may be associated with decreased testosterone production in men compared to higher-fat diets. Healthy testosterone levels not only positively impact sexual function, but also support optimal muscle growth, bone strength, and more.  

But not all sources of fat are equally beneficial. Your best bet: Focus on sources of unsaturated fats, including monounsaturated fats (MUFAs) and polyunsaturated fats (PUFAs) like omega-3s and omega-6s. Try to also minimize intake of saturated fat (SFA), which contributes to elevated LDL cholesterol, arterial plaque buildup, and inflammation. Replacing SFAs with unsaturated fats is associated with a reduced risk of death from a variety of diseases, including cardiovascular disease and cancer. 

Macronutrient Food Sources

To get a solid balance of macronutrients in your diet, aim for meals and snacks to contain a mix of minimally processed carb-rich, protein-rich, and fat-rich food sources. 

Carbohydrate Food Sources

Focus on unrefined, minimally processed carb-containing foods, which naturally contain fiber and a variety of beneficial phytochemicals. Here are a few examples to add to your grocery list:

Protein Food Sources

Focus on high-quality animal products (while trying to limit processed meats) and protein-rich plant foods. Remember: Eating a variety of plant foods will help ensure you get all nine essential amino acids. Here are a few protein food sources to keep in mind:

Fat Food Sources

Focus on nutrient-dense foods rich in unsaturated fats, including PUFAs (omega-3s and omega-6s) and MUFAs, and minimize intake of saturated fats. Here are some fat sources to consider adding to your plate:

Is There an Ideal Macro Ratio?

There’s no one-size-fits-all macro ratio that’s most beneficial for health. There is, however, something called the Acceptable Macronutrient Distribution Ranges (AMDR) set forth by the National Academy of Sciences, which suggests that adults consume 10–35 percent of our calories from protein, 20–35 percent from fat, and 45–65 percent from carbohydrates. Protein needs are also commonly determined based on body weight, with a recommended dietary allowance (RDA) of 0.8 grams of protein per kilogram of body weight per day, or 54 grams of protein for a 150-pound person—but some experts and health organizations view the RDA for protein as a baseline and say active individuals need more.

“Those are pretty flexible ratios, which is great because every body is different,” Nielsen says. “Some people thrive on a higher carbohydrate diet while others feel better when they prioritize fats and protein.” If you have prediabetes, for example, and you want to improve blood sugar levels, you may opt for fewer carbs and a higher percentage of protein and fat. On the other hand, if you’re engaging in high-intensity workouts, your carb and protein intake may need to be higher. 

When it comes to protein specifically, some research suggests that people engaging in low, moderate, and intense physical activity should get more than the RDA guideline—1.0, 1.3, and 1.6 grams per kilogram of body weight, respectively. (Following the same example above, that would work out to be 68, 89, or 109 grams of protein per day for a 150-pound person.)

Interestingly, for people who menstruate, the optimal macro ratios can change throughout your cycle. “During the follicular phase [days 1–14], when estrogen levels are higher and your body is using more carbs for energy, you may find that you crave carbohydrates more,” Cording says. “During the luteal phase [days 15–28], as your body prepares for menstruation, there is a shift to relying more on fat and protein for energy. Getting more of these nutrients at this time could help support satiety if you struggle with cravings or feeling extra hungry right before your period.”

Your personal “ideal” macro breakdown might change over time, too, per Cording—so be mindful of any changes in athletic performance, body composition, weight trends, energy levels, appetite patterns, mood, and mental focus, and tweak your intake accordingly.  

Should You Count Macros?

Probably not. While some people meticulously track macros for various reasons—from bodybuilders looking to lower body fat and build muscle to people with diabetes trying to stabilize blood sugar levels to distance runners looking to boost recovery—counting macros may not be so beneficial for the average person. And for some, particularly those with a history of eating disorders, it could lead to a disconnection from hunger and fullness cues, an unhealthy preoccupation with food, and a lack of dietary flexibility.

Instead, most nutrition experts recommend eating a generally balanced diet and then increasing or decreasing your intake of protein-, carb-, and fat-containing foods based on how you feel and your personal health goals. If you do want to track macros for a specific health goal, consider working with a registered dietitian (at least initially) who can get you started on an appropriate plan for your needs. 

Tips for Balancing Macronutrients

Given the unique roles of carbohydrates, proteins, and fats in the body outlined above, it’s vital that we get a balance of these macros in our diet to support optimal health. But how do you do that if you’re not counting macros? “As a dietitian who doesn’t really encourage nutrient tracking, I typically use something called the plate method,” Nielsen says. “When you look at your plate, aim for roughly 50 percent of your plate to be covered in fruits and vegetables, 25 percent in protein-rich foods, and 25 percent in whole grains or starchy carbs (e.g. sweet potatoes), and use a little fat in your cooking. You can shift those ratios to help tweak how you feel and, of course, not every meal has to look like that.”

Snacks should also contain some carbs, protein, and fat—although you don’t necessarily need to be as picky about percentages. Consider options like an apple with string cheese, whole wheat toast with peanut butter and banana, or trail mix with nuts, seeds, and dried fruit. 

The Takeaway

Getting a balance of macronutrients is essential for your well-being and supporting a healthy fitness routine. Carb-containing foods provide energy for workouts, help preserve your muscle mass, and can be a great source of micronutrients; protein-rich foods support tissue growth and repair, boost muscle gains, promote stable blood sugar, and support immune function; and sources of healthy dietary fats create healthy cells, promote stable blood sugar, enhance absorption of nutrients, support hormones, and even curb inflammation. Getting adequate amounts of each macro (and boosting your intake of micronutrients in the process) is best accomplished by including a balance of minimally processed carb-, protein-, and fat-containing foods at each meal and snack, and adjusting based on how you feel.

This content is for informational and educational purposes only and does not constitute individualized advice. It is not intended to replace professional medical evaluation, diagnosis, or treatment. Seek the advice of your physician for questions you may have regarding your health or a medical condition. If you are having a medical emergency, call your physician or 911 immediately.