Macronutrients 101

Macronutrients are the building blocks of the human diet and are essential for optimal health. From carbohydrates to protein to fat, here is everything you need to know about macronutrients; where to find them, why you need them, and how much you need.

What are macronutrients?

Macronutrients are nutrients required in large quantities in the diet, specifically fat, carbohydrates, and protein, which provide us with energy to do everything from developing and repairing tissues to regulating bodily processes. Macronutrients are present in food, each with a unique set of properties that influence our health and make up the calorie content of food.

• Protein provides 4 calories per gram
• Carbohydrates provide 4 calories per gram
• Fat provides 9 calories per gram

Macronutrient Functions

Here is a breakdown of the functions of carbohydrates, proteins, and fats.

Carbohydrates

Carbohydrates function primarily as a source of energy. Carbs play key roles in digestion and gut health, glucose, and insulin action, as well as cholesterol and triglyceride metabolism (1). Carbohydrates include starches, fibers, and sugars, and can be further classified in terms of structure as complex and simple carbohydrates.

• Simple carbohydrates consist of one (monosaccharide) or two (disaccharide) sugar molecules. These forms of carbohydrates can be broken down and used as energy quickly by the body and have a sweet taste. Simple carbohydrates are found naturally in fruits and milk and can also be found in the form of refined sugar in items such as candy, table sugar, and soft drinks.
• Complex carbohydrates consist of short and long chains of monosaccharide units, including polysaccharides such as starch or cellulose. Complex carbohydrates typically have a savory taste, naturally contain fiber, and are found in starchy carbohydrates such as oats, rice, potatoes, beans, lentils, and starchy vegetables.
• Dietary fiber falls under the umbrella of carbohydrates, specifically complex carbohydrates, and is also required in large quantities in the human diet. There are 2 primary types of fiber – soluble and insoluble – and both are important for health, digestion, and lowering the risk of disease. Fiber provides, on average, 2 calories per gram (2).

Carbohydrates contain 4 calories per gram and are found in whole grains, beans, lentils, fruits, vegetables, and dairy.

Proteins

Protein is considered an essential nutrient because the body cannot biosynthesize enough to maintain health and survival. Proteins are large molecules composed of amino acids, which play many crucial roles in the body. The amino acids that make up protein function as structural components, such as skeletal muscle, enzymes, hormones, immune factors, transporters, acid-base regulators, and neurotransmitters. The single largest tissue store of bodily protein in skeletal muscle (3).

There are 2 types of amino acids: non-essential and essential. Of the 20 amino acids that comprise protein, nine are considered essential and, therefore, must be obtained from food. Foods that contain all nine essential amino acids are considered complete protein sources, while those that only contain some of the 9 essential amino acids are considered incomplete protein sources.

Protein contains 4 calories per gram and is primarily found in animal foods such as red meat, fish, shellfish, poultry, eggs, yogurt, and some other dairy products. These protein sources contain all essential amino acids. Protein can also be found in lower concentrations in soy products like tofu and tempeh, as well as beans and lentils. These protein sources do not contain all essential amino acids.

Fats

Fats are made of smaller molecules, called fatty acids, which play several roles in the body including the metabolism of fat-soluble vitamins, cell membrane function, the maintenance of structural integrity of the brain and nervous system, and hormone synthesis. There are two primary types of dietary fat; saturated fat and unsaturated fat, both of which are essential to health.

• Saturated fats contain no double bonds in their structure, as the chain has been “saturated”, and are, therefore, generally solid at room temperature.
• Unsaturated fats, on the contrary, have one or more double bonds in their structure and are, therefore, generally liquid at room temperature. Monounsaturated fats have one double bond and polyunsaturated fats have more than one.

Like protein, fat is considered an essential nutrient because the body cannot manufacture sufficient amounts of certain fats, specifically essential fatty acids linoleic acid (omega-6) and alpha-linolenic acid (omega-3), for survival so it must be consumed through food.

Dietary fat contains 9 calories per gram and is found in animal foods, oils, butter, nuts, seeds, avocado, and olives.

Macronutrient Sources

Almost all foods contain more than one macronutrient, sometimes all three, however, foods are generally classified by the macronutrient they contain the most of.

Sources of carbohydrates include:

• Whole Grains: Oats, rice, corn, farro, barley, millet
• Grain Products: Bread, pasta, pita, cereals
• Vegetables: Squash, pumpkin, potatoes, peas, carrots, asparagus, broccoli,
• Fruit: Bananas, apples, pears, berries
• Legumes: Beans, lentils, chickpeas
• Dairy Products: Milk, yogurt

Sources of protein include:

• Red Meat: Beef, pork, bison, lamb
• Poultry: Chicken and turkey
• Seafood: Salmon, tuna, cod
• Shellfish: Shrimp, lobster, crab, oysters
• Eggs
• Dairy Products: Milk, yogurt, cheese
• Legumes: Beans, lentils, chickpeas
• Soy Products: Tofu, tempeh, edamame

Sources of fat include:

• Oils: Olive oil, avocado oil, coconut oil
• Dairy Products: Milk, butter, cheese, yogurt
• Nuts and Seeds: Almonds, cashews, chia seeds, flax seeds
• Animal Fats: Fatty fish, red meat, fatty cuts of meat

Is water a macronutrient?

While not always considered one, water is technically classified as a macronutrient because it is required in large amounts, however, unlike carbohydrates, protein, and fat, water does not contain carbon or yield energy (4).

How are macronutrients different than micronutrients?

Macronutrients differ from micronutrients. While both are essential, macronutrients are required in larger amounts, and micronutrients are required in smaller amounts. Macronutrients include carbohydrates, protein, and fat, while micronutrients include vitamins and minerals such as calcium, magnesium, and vitamin D. Micronutrients do not provide calories.

What is the ideal macronutrient breakdown?

The number of macronutrients consumed relative to total daily calories is known as macronutrient breakdown or macronutrient split. The dietary guidelines for macronutrient ratio intakes, provided by the United States Department of Agriculture (USDA) and the Food and Nutrition Board of the Institutes of Medicine (IOM), are (5)(6):

• Carbohydrates: 45 – 65% of total daily calories
• Fats: 20 – 35% of total daily calories
• Proteins: 10 – 35% of total daily calories

The ranges are to be seen as general guidelines as personal needs vary based on sex, height, weight, activity level, age, goals, and other factors. If you are unsure of your personal needs, it is best to work with a registered dietitian, registered nutritionist, or professional health practitioner to determine optimal macronutrient intake for your personal health goals.