Nutrition 101: Calories and Macronutrients

Welcome to the third of five blogs, as part of the series: Nutrition 101!

Make sure to check back at taylorwhisman.com every Saturday for new articles.  A full list of the topics covered can be found here.  Each article is published in a specific order, so make sure that you don’t miss out!  Subscribe (on the right if you’re on a computer and at the bottom if you’re on a smartphone) to get notified of new posts and to support the spread of easy-to-digest (pun intended) health information.

Now that we understand metabolism and energy balance, it’s time to discuss the VIPs – calories and macronutrients. We will get into a bit more discussion on energy, but calories are a form of energy, after all. This stuff is important!

The Relationship Between Calories and Macronutrients

After reading last week’s article, you now know that calories are a form of energy and that our bodies need calories to function and obtain energy, but where do they really come from?  

Remember last week when we talked about calories in, calories out? Total calories tells us which side of the energy balance equation we are sitting on. Information about macronutrients and their role in the human body will give us more information on how we can make our nutrition work for us!

Macronutrients are comprised of protein, carbohydrates, and fat. They are called macronutrients because your body needs them in relatively large quantities (hundreds of grams at a time).  This is in contrast to micronutrients, and food contains both types of nutrients, but we will discuss “micros” in more depth in the next article.  For now, macros are our focus.  I call them big molecules because, compared to a chemical compound like water, they contain WAY more atoms which are attached to one another through strong bonds.

Here’s a little chemistry lesson for you: 

You couldn’t get through this series without learning a little!  I am a chemist, ya know.  

Macronutrients have particular bonds between the atoms, and these bonds contain stored energy.  When the enzymes in your body break these bonds upon digestion, energy from the bonds is transformed so that the body can use it!  Pretty cool, huh?  

I will admit to oversimplifying this a little bit… What I am failing to mention here is the multitude of chemical processes going on during digestion – collectively known as cellular respiration. Does anyone remember this from Biology 101?  It’s essentially a bunch of oxidation and reduction reactions where hydrogen atoms and electrons get shuttled around, and you’re left with energy in the form that your body can use = ATP.  This is so amazing to me that our bodies do this!!  Clearly, I’m leaving a lot of details out here, but the goal is to understand nutrition and food, not biochemical details.  While your body breaks down each macro (protein, carb, fat) a little bit differently, the concept is still the same.

The take-home message is that macronutrients supply us with energy, measured by calories, converted to ATP by our bodies.  Confused?  A calorie is a unit of measure for energy.  ATP is a molecule that our body uses AS energy

Remember, ALL molecules contain energy within their bonds, not just macronutrients.  If you still don’t understand, feel free to reach out to me (I’m serious – I love it when people ask me questions, especially when I don’t know the answer).  

To sum up this first part, macronutrients are molecules found in food, and now we know that energy comes from the breakdown of macronutrients by your digestive system, which converts this energy to ATP.  So, you can almost use calories and macronutrients interchangeably… but not really.  

How much energy do we get from macronutrients?

First of all, all three have a specific biochemical identity and specific role in the body, and YOU NEED ALL THREE for optimal health. 

We know the amount of energy (in the form of calories) that each macronutrient provides the body because we can measure this using physical experiments.  This is how a Nutrition Facts label is able to be created for each type of food you consume.  

  • 1 gram of protein = 4 calories
  • 1 gram of carbohydrates = 4 calories
  • 1 gram of fat = 9 calories 

Caloric content of food describes how much energy you will be consuming overall, but it doesn’t give the entire picture.  Macro content of food describes where the energy is coming from and how that food will be used by your body. Many foods contain all three macros.

Let’s take a McDonald’s McDouble for example.  Their website says each sandwich has 390 calories.  Does this give the full picture?

It has 18 grams of fat, 33 grams of carbohydrates, and 22 grams of protein.  Let’s do the math, and see if it adds up.  

  • 18 grams of fat x 9 calories per gram of fat = 162 calories
  • 33 grams of carbs x 4 calories per gram of carbs = 132 calories
  • 22 grams of protein x 4 calories per gram of protein = 88 calories
  • Adding up the total calories, we get 382 calories… Hmmm, that’s not 390, which is what McDonald’s reported.  

If you are a person who loses sleep at night because you didn’t hit your macros, then this might hurt your ego a little bit.

It turns out that most Nutrition Fact labels are not 100% accurate.  After some assumptions and rounding, they can deviate by up to 20-25%!  If you’ve ever been a perfectionist in counting your macros, then the joke’s on you.  I don’t mean to be a jerk, but folks who obsess over their macros aren’t any better than folks who estimate their macros.  We are only as good as our experimental error with this!

Either way, we should still care about how many calories we consume and do our best with what we have.  If you’re interested in tracking macros, see my Instagram post on the benefits and downsides of tracking them.

Now let’s dive into the specifics of each type of macronutrient, their importance, and how much of each one to consume.  Disclaimer: I am not telling you how many calories to consume or what your macros should be. I am reporting what the current research supports in terms of ranges for a healthy individual. If you want customized numbers, consider investing in a nutrition coach.  


Second to water, protein is the most abundant molecule in your fat-free tissue.  It is used for a multitude of processes like energy production, cell signaling, nutrient transport, and more.

Protein is a macronutrient, which can be referred to as a macromolecule. It is a macromolecule because it is a big molecule made up of smaller molecules bound together by peptide bonds.  These smaller molecules are called amino acids. Your body has the ability to break these bonds and use these amino acids in numerous ways!

Importance of Protein

Protein is essential to the human diet. Protein is so essential, in fact, there is a recommended amount of protein you should be eating to stay healthy, which has been extensively researched by the Food and Nutrition Board of the Institute of Medicine, National Academy of Sciences. 

Acceptable Macronutrient Distribution Ranges

Before we go any further, we must define AMDRs, or Acceptable Macronutrient Distribution Ranges. Since we know that macronutrients are what make up calories, percentage of total calorie ranges have been defined for each macronutrient, also known as AMDRs, which are established

“based on evidence from interventional trials, with support of epidemiological evidence that suggests a role in the prevention or increased risk of chronic diseases, and based on ensuring sufficient intakes of essential nutrients.” (Institute of Medicine, 2005)

How much protein do you need then?

According to the Institute of Medicine, you should aim to get between 10 – 25% of your calories from protein.  The range exists because all of us are different with different goals and baseline health needs. 

As a coach, I make recommendations based on bodyweight and athletic goals, if applicable.  My recommendations fall within these values. 

For the general population, 0.8 g – 2.2 g per kg of bodyweight is an acceptable range. I realize this is a wide range, so it’s necessary to first determine what your goal is and then tailor from there. 

Someone who is largely sedentary might only need about 10% of their calories from protein, whereas someone who lifts weights 5 days per week might need the maximum of 25% of their calories from protein!  

What about amino acids?

Not all protein sources are identical. Say what?  Because protein is made up of amino acids, there are going to be key differences in the types of amino acids from meat compared to vegetables compared to grains, etc.  

There are 20 amino acids total, 9 of which are essential (EAAs).  This doesn’t mean that they are “important.”  Essential, in nutrition terms, means that your body needs it but can’t make it on its own, and it MUST be obtained through diet.

Not all foods that contain protein will contain the 9 EAAs.  This means that they are incomplete proteins.  The foods that DO contain all EAAs are complete proteins.  The majority of food items don’t give an amino acid profile, so you’ll have to check that out for yourself to make sure you’re getting all of yours.  Consuming  protein from a variety of sources in your diet is a good protocol to ensure that you are getting all of your EAAs.

For more specifics on protein, check out another blog article I’ve written that covers more about how much protein to consume and when to consume it.


Carbohydrates, or carbs for short, get a lot of bad rap!  Carbohydrates are essential to the human diet, so let’s find out why.

Importance of Carbohydrates

Carbohydrates are important and useful in the human diet because they provide us with an immediate source of energy, and they are also the body’s preferred source of energy. The health benefits of consuming carbohydrates include providing energy, supplying fiber, and preventing deterioration of muscle tissue.  Carbohydrates can help prevent deterioration of muscle tissue because they are the primary source of energy for your cellular processes.  When your body is short of carbs, it will turn to muscle tissue to make its own glucose from your precious gains.  This process is called gluconeogenesis

Chemical Structure

Types of carbohydrates include starches and sugars.  Like protein, carbohydrates can be considered macromolecules made up of smaller units or building blocks – glucose, fructose, and galactose – also known as monosaccharides.  

Sugars are small carbohydrate units called monosaccharides and disaccharides (1 or 2 building blocks).  Sugars are carbs found in fruit, milk, sweets, and table sugar.  Starches are usually oligosaccharides (between 3 and 10 building blocks).  Starches are carbs found in grains, corn, rice, veggies, beans, and wheat.  

How many carbohydrates do you need to be healthy?

According to the Institute of Medicine, you should aim to get between 45 – 65% of your calories from carbohydrates.  As with protein, the range exists because all of us are different with different goals and baseline health needs.  Oftentimes, carbs get demonized because they are in a lot of foods; however, it is clear that our bodies need them to function properly.  


Fiber is a special type of carb!  Fiber is necessary in the human diet, but we often don’t get enough… and yes, carbs from fiber still count.  While they cannot be digested like a normal carbohydrate, they should still be accounted for in your total energy intake. 

Females need 25 g per day, and males need 38 g per day!  Are you getting enough?

While I don’t have the time to go into all the details, there are two types of fiber – soluble and insoluble, each with their own unique benefits. The collective benefits of fiber in your diet include, but are not limited to, weight loss, reducing your risk of heart disease, GI regularity, diabetes, protection, and improved adsorption of nutrients in the food. 

What about sugar?

The American Heart Association recommends limiting sugar intake to 6 teaspoons for women and 9 teaspoons for men.  Let me make this very clear.  Sugar is not inherently bad.  The problem (at least in America) is that we are consuming too much from habitual poor food choices! Increased amounts of sugar from hyperpalatable foods like desserts and sugary drinks lead to an increase in consumed calories over time which leads to weight gain.  Excess body weight may then lead to disease.  

If you’d like to learn more about carbohydrates, then suggest a it as a topic for a future blog article!


Like protein and carbohydrates, fat is vital to consume in your diet so that many processes in the body can take place properly such as hormone shuttling and vitamin absorption.  Fat provides your cell membranes with their structure and function as well as providing insulation and temperature regulation.    

Importance of Dietary Fat

Fatty acids, which are the building blocks of dietary fats, help shuttle hormones throughout your body. In addition, you need fat to help transport cholesterol to and from your liver.  Fat-soluble vitamins include Vitamins A, D, E, and K. These cannot be absorbed by your body unless you consume fat in your diet.  Essential fatty acids are, you guessed it, fatty acids that you can only obtain from your diet, and these include omega-3s and omega-6s.  These are important for decreasing your risk of cardiovascular disease and have anti-inflammatory properties.

Chemical Structure

Chemically, fats are composed of three long chains of carbon connected to a headgroup, called glycerol. The entire molecule can be referred to as a triglyceride.  Triglycerides are the main component of dietary fats, and your body digests them to break them down into their fatty acid substituents. Learn more about their structure here.   

How much fat do you need? 

The AMDRs for fat are between 20 – 25% of your calories from fat.  However, it is recommended that you consume <10% of your calories from saturated fat!  Saturated fats in large quantities are not heart-healthy, because their respective carbon chains (in the fatty acid) can stack with each other, potentially causing blockages in your arteries.  Unsaturated fats do not have the ability to stack as efficiently because they contain unsaturated carbon bonds.  Think about an unsaturated bond as a defect that prevents it from aligning properly with other chains in the fatty acid. This is why I like to talk about the chemical structure of each macro, because it helps you to see why there is a certain amount that you should consume!

If you’d like to learn more about dietary fat or how it might relate to body fat, suggest it as a topic for a future blog article.

Final Remarks

This brings me to the end of the third blog in Nutrition 101!

I realize that I am leaving out a lot of details, but I believe that I’ve included enough information to cover the basics.  There are entire books written on some of the topics that I’ve mentioned in this article, and I didn’t want to make this super long. I hope that it was easy to understand, and most of all, informative.

Again, if you have questions or concerns with this week’s blog, please reach out to me.  I am very receptive to constructive criticism because it helps me improve!  

Next week’s blog is going to be all about micronutrients, which many of us overlook in our diets.  Stay tuned, and make sure to subscribe to get notified when it is posted!

If you appreciate my free content, follow me on Instagram to see more, or buy me a coffee, which helps me to keep learning, studying, and educating you guys!



Lowenstein JM (1969). Methods in Enzymology, Volume 13: Citric Acid Cycle. Boston: Academic Press. ISBN 978-0-12-181870-8


Norton, L. E., & Wilson, G. J. (2009). Optimal protein intake to maximize muscle protein synthesis. AgroFood Industry Hi-Tech, 20, 54–57.
Pencharz, P. B., Elango, R., & Wolfe, R. R. (2016). Recent developments in understanding protein needs – How much and what kind should we eat? Applied Physiology, Nutrition, and Metabolism, 41(5), 577–580. doi:10.1139/apnm-2015-0549.
American Heart Association, (2016). Added Sugars. Retrieved from https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sugar/added-sugars
Dahl, W. J., & Stewart, M. L. (2015). Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber. Journal of the Academy of Nutrition and Dietetics, 115(11), 1861-1870. doi:10.1016/j.jand.2015.09.003
Thompson J, and Manore M (2006). Nutrition: An Applied Approach. San Francisco, CA. Pearson Education, Inc.  
US Department of Health and Human Services; US Department of Agriculture. 2015-2020 Dietary Guidelines for Americans. 8th ed. Washington, DC: US Dept of Health and Human Services; December 2015. http://www.health.gov/DietaryGuidelines. Accessed September 2018.

Make sure to click the pink highlighted text within the article to see other references not in this list.

Photos by Polina Tankilevitch from Pexels

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