Macronutrients, macros for short, are proteins, carbohydrates, and fats. This article explains the nuances and dietary implications within each.

Proteins

When ingested, proteins are broken down into their simplest units, amino acids. After absorption, the amino acids are reconstituted back into proteins. Proteins comprise a variety of structures, e.g., cell receptors, hormones, enzymes, tissue, and muscle.

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Although not the preferred energy source, when consumed in excess, protein is converted to glucose for energy if needed or fat if not. Protein contains four Calories per gram.

Humans can make 11 of the 20 amino acids that comprise proteins. Of the remaining nine, even one is missing, protein production cannot happen. While animal sources contain ratios of these nine essential amino acids in the combinations that humans need, plant sources contain protein in different ratios and therefore humans cannot use all of their protein.

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Although the usable protein varies from food to food, and is not usually not considered in recommendations, generally, a minimum of 0.36 grams per pound of body ideal body weight is recommended for sedentary individuals. This increases to one gram per pound for those engaged in the most intense resistance training or recovering from injury or surgery.

Carbohydrates

Like protein, carbohydrates have four Calories per gram. Their simplest unit is a monosaccharide. The most common monosaccharides humans consume are glucose, fructose, and galactose. These normally combine to form polysaccharides of two units to several hundred.

Disaccharides consist of two monosaccharides and complex carbohydrates have three or more monosaccharides linked together. Amylose and Amylopectin, starches, are long straight and branched chains of glucose molecules respectively. Their complex nature delays enzymatic breakdown into the absorbable monosaccharides.

Indigestible carbohydrates include fiber, from plants, which provides food for the highly important gut microbiota.

Most plant foods, in their whole food form contain insoluble fiber. This gels around the carbohydrates, further slowing digestion.

Refined carbohydrates, however, are usually mono or disaccharides or starch without their natural fiber. So, they are digested and absorbed rapidly, spiking blood glucose, contributing to type 2 diabetes.

Fats

Fats contain nine Calories per gram. They consist of saturated, monounsaturated, and polyunsaturated fatty acids. Monounsaturated and polyunsaturated fats lower a marker for cardiovascular disease, low density lipoprotein (LDL). Conversely, saturated fats raise this marker. Saturated fats may also contribute to insulin resistance, a key component of type 2 diabetes.

Essential fatty acids (EFAs) are polyunsaturated fats humans cannot make internally but are critical for survival. So, their consumption is necessary. There are two categories, omega-6’s and omega-3’s. Omega-6’s are abundant and generally have proinflammatory effects whereas the omega-3’s have anti-inflammatory effects. The three types of omega-3s are interconvertible, but the conversion to the forms found in marine life (EPA and DHA) is limited. So, consumption of fatty fish or supplementation may be needed.

Quantity Recommendations

Most simply and approximately, protein should constitute 25% of total calories, carbohydrates 50%, and fats 25%.

So, for example, a person of 150 lbs ideal body weight engaged in moderate to high resistance training requires approximately 0.6g protein per pound. This was estimated from the between 0.36g/lb and 1g/lb recommendation. This calculates to 90 grams of protein equaling 360 Calories (4×90). Doubling this results in the approximate carbohydrates needed, 720 Calories, or 180 grams. If fat constitutes 25%, then approximately 360 Calories or 40g (360/9) of fat should be consumed.

Carbohydrates and fats should be from unrefined vegetation such as vegetables and beans, legumes, etc. Fats should be from whole nuts, seeds, and avocado with marine sources for their omega-3 content.

Patrick Traynor, PHD, MPH, RD, CPT is a registered dietitian with an insurance-based practice, MNT Scientific in South Lake Tahoe & Sacramento, CA, Minden, NV, Ashland, OR, and does telehealth. Appointments can be requested online at MNTScientific.com. Inquiries can be directed to info@mntscientific.com.