Mountaintop Medicine: Nutrition Notes — A Brief Introduction to Carbs, Fats, and Proteins

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Leah Gardner, EPH Registered Dietitian

Hello dear readers, and welcome back to another edition of Mountaintop Medicine: Nutrition Notes!

Today we’re diving into the world of macronutrients- these nutrients are considered the cornerstones of our diet. As a registered dietitian, I often explain that each of these macronutrients plays a crucial role in our bodies, and it’s important to have a good balance of all three in your diet. They provide us with energy, prevent disease, and allow our bodies to develop, grow, repair, and maintain their structure and function. Macronutrients are the 3 major nutrient groups our bodies need in large amounts to function optimally, hence the term, “macro.” Carbohydrates, proteins, and fats are the three main macros. They’re considered essential nutrients- this means that your body is either unable to make them or cannot make enough of them.

Each of the three macronutrients produce energy in the form of calories. Carbohydrates are our body’s main source of fuel, but the fats and proteins we eat can are also used to create energy if needed. This is all completed in a process called energy metabolism. During digestion, each macronutrient is broken down into smaller parts. These parts are then used for body functions like energy production, muscle building, and giving structure to all our cells. For example, proteins provide essential amino acids, while fats provide essential fatty acids.


Carbohydrates, otherwise known as, “carbs,” are found in fruits, veggies, grains, beans, legumes, dairy products, potatoes and corn, and in sugary desserts. Most carbs are broken down into glucose, or into sugars, in the body- however this does not apply to dietary fiber, a type of carb that isn’t broken down. Although some fiber can be absorbed by tiny microbes in your colon, it mostly passes through our bodies undigested and promotes healthy bowel movements. Carbs provide us with instant energy for our brains, central nervous system, and red blood cells. The glucose component from carbohydrates can be stored as glycogen in our muscles and liver for later use when we need energy, like during long periods of endurance exercise or during fasting.


Fats can be found in vegetable and seed oils, butter, avocados, nuts and seeds, dairy products, fatty fish, red meats, and in processed and pre-packaged foods. Fats are broken down into fatty acids and glycerol after digestion. Despite its unfortunate reputation, fat is essential for our body’s health- it helps us absorb vitamins and minerals and plays a crucial role in our immune system. The fat stored around your body serves as an energy reserve that can be used in times when you eat fewer calories than you burn. It is an essential component of our cell membranes and helps transport and promote the absorption of vitamins A, D, E, and K. Fat also insulates and protects our organs.


Proteins are the building blocks of our body. Poultry, red meats, fish and seafood, eggs, dairy products, beans and legumes, nuts and seeds, and soy products are all sources of protein. Proteins are broken down into amino acids during digestion. There are twenty amino acids that have important functions in our bodies, 9 of which are essential and must be obtained from foods. Protein is important for building and repairing tissues and muscles. They provide structure to our cell membranes, organs, hair, skin, and nails. They also help to maintain a healthy acid-base balance and are used to create enzymes and hormones that our bodies need.

How much do you need?

Although there are recommended ranges for macronutrient intake, your needs vary based on personal circumstances such as age, gender, how active you are, or whether you have a chronic condition like diabetes.

The USDA has set these macronutrient ranges for the average adult:

Carbs: 45-65% of your daily calories

Fat: 20-35% of your daily calories

Protein: 10-35% of your daily calories

For example, a person consuming 2000 calories per day would aim for a range of 900-1300 calories from carbohydrates, or 260-380 grams, 400-700 calories from fat, or 44-78 grams, and 200-700 calories from protein, or 50-175 grams.

Remember, each macronutrient is incredibly important for your body to function optimally. It’s crucial that you get in enough carbs, protein, and fat by eating a balanced diet comprising a variety of foods. If you have any questions or if there are any nutrition-related topics that you would like me to discuss, please email me at