Food is so often surrounding by anxiety, duty, guilt or pleasure. But when you strip away the clever packaging, tasty engineering and the stigma about which food is “right” or “wrong,” food is just made of protein, fats and carbs.
It is a little strange to acknowledge this since food is the source of so many emotionally-charged opinions. From the American Heart Association to your next door neighbor, we are constantly being inundated with information about the latest research on restaurants, fad diets, ethical food sources, organic, non-GMO, cholesterol and the environmental impact all of these choices have. A good understanding of nutrition comes from a foundation of knowing the basic biochemistry of what makes up our food at the molecular level.
There are three macronutrients, called “macro” because they are the main, big ones. These are proteins, fats and carbohydrates and together they are the building blocks for the body’s energy systems. These building blocks are needed to make the gasoline that keeps the complex engine of your body running. Macronutrients themselves are made up of calories which are simply of unit of measuring energy. If your goal is to lose weight, calories do matter and it can be valuable to count your macros if you want to optimize your energy, recover from training and build lean muscle mass during your diet.
Calories per gram → 4
Smallest unit of measure → glucose
Primary function → energy
Forget, for a moment, everything you have ever heard about carbs.
Carb intake depends on so many factors like how big or small someone is, how much lean body mass they have, how active they are, how old they are, genetics and their personal goals. For example, if you take an 18 year old male swimmer who has practice twice a day, their carbohydrate needs will look much different than a 60 year old woman who takes an aerobics class once a week. Which is one reason why there is no singular way of eating that is best for everyone.
When you eat carbohydrates, whether sweet potatoes, donuts or a teaspoon of sugar in your coffee, your digestive system breaks this down into glucose. This glucose is transported to the liver for entrance into the bloodstream until it is taken up by our cells. Typically, our body maintains about 20 grams of glucose in our bloodstream at all times. This is known as “blood sugar.” If these levels drop lower (like while exercising or just from our body’s metabolic needs), this will trigger the release of new glucose supply from where it has been stored either in the liver or in the muscles. If blood sugar is too high, the glucose will be stored up to maximum capacity in the liver and muscles. Once those storage units are full, the body will then signal glucose to be converted to body fat.
You can see, if you are exercising and depleting your store of glucose, your body will begin releasing more and more glucose for its needs until all of the store units are empty. At this point, it will begin breaking down body fat to make glucose for its energy requirements. This is why you burn fat when in a calorie deficit: when the body’s energy demands are higher than the free-floating energy supply.
So, it comes down to a balance of Energy In versus Energy Out, which is why eating in a calorie deficit helps you burn body fat and eating in a calorie surplus causes you to store body fat.
Let’s talk for a moment about Insulin, which is a hormone secreted by the body in response to blood sugar levels. The body responds differently to different types of carbohydrates based on how quickly that carbohydrate raises your blood sugar. For example, eating a sweet potato will cause an Insulin response, but a much lower one than eating a donut. Insulin tells your cells to open up and let in the glucose for energy and it can stimulate all sorts of positive reactions in the body that help us build muscle, lower stress hormones (like cortisol) and recover from physical stress (like exercise). This is why your coach may recommend eating something sugary like fruit or candy during and after a workout. Insulin is not a bad thing -- the problem with Insulin comes from when it is so often released that our body starts to ignore it. This is more or less what happens with Diabetes II. This affects the metabolism because when we become insensitive to Insulin, the body will not uptake the glucose and use it, causing the storage of more body fat. Exercise improves our ability to utilize glucose as energy which is why regular exercise improves metabolic function and Insulin sensitivity. We want to be sensitive to Insulin and we want our body to use our supply of glucose.
Not all carbohydrates are created equal. Carbohydrates high in fiber and starch like root vegetables, grains and beans digest slower in the body, releasing the glucose into the body at a slower, more steady rate. This will keep you feeling full longer throughout the day and keep your Insulin levels more stable. When you eat foods high in refined sugar or fruit sugars, this will give you an immediate rush of energy that will dissipate more quickly. So, you can see there are benefits to either type of carbohydrate like when you are in the middle of a difficult, two hour training sessions versus when you are about to go into a long meeting at work and won’t eat dinner for another six hours. There is no “right” or “wrong” type of food so long as you match the food to your body’s needs and your current goals.
Your beautiful brain needs 130g of glucose per day to function and if this glucose isn’t coming from our dietary carbohydrate intake, the body is able make it from breaking down proteins (gluconeogenesis) or breaking down fats like in ketosis. This is why low carbohydrate nutrition protocols can work for people, but why it isn’t necessary for fat loss. Which brings us to our next macronutrient.
Calories per gram → 9
Smallest unit of measure → fatty acid
Primary function → energy, satiety, hormone regulation
Dietary fat does not make you fat. As you saw in our previous section, body fat is stored when there is too much glucose in the body due to eating in a calorie surplus and not using the energy that this glucose is offering.
Fats from our food are broken down in the digestive system by various enzymes and biochemical reactions and take several hours before they enter the bloodstream as fatty acids. This very slow digestive process is helpful in giving you a sense of feeling full for longer. Fat eaten along with protein slows its digestion as well, which helps your body to absorb proteins more effectively. (We will get into that more later.) Once fatty acids are in your bloodstream, they are either broken down further and used as energy for the body, or they are converted back into Triglycerides to be stored as body fat.
Dietary fat has several major functions in the body.
- It provides us with energy and seeing as how it is the most energy dense of the macronutrients, it gives us a lot of energy per volume of food consumed.
- It helps us create and balance hormones such as cortisol, serotonin and the sex hormones like testosterone, progesterone and estrogen to name a few. This is why your nutrition coach may recommend a fat minimum in your diet to prevent issues with your delicately balanced sex hormones getting out of whack when cutting body fat.
- It makes up our cell membranes, our brain and components of our nervous system.
- It helps transport fat-soluble micronutrients that are vital for our body’s function like Vitamins A, D, E and K.
In the absence of carbohydrates from the diet, our bodies can create glucose from fatty acids using a process called Ketosis. This ensures that glucose will be provided to the brain and our fundamental systems. As humans, we actually can exist without carbohydrates but absolutely cannot exist without fat. To see this in history, we can look at early settlers in North America that hunted wild rabbits and attempted to live solely off this meat. Wild rabbit is extremely lean meat and without enough fats in their diet, many of these settlers died of starvation even though they were, in fact, eating.
While we could go deeper into the different kinds of fat structure and how they affect our bodies, for now let’s say that getting a variety of fats from all different sources has the most positive effect on our body’s systems. Dairy like butter and cream, animal fats from meat and fish and fats from nuts, seeds and oils like coconut or olive all make up the spectrum of calorically dense foods that provide us with a ton of energy.
Calories per gram → 4
Smallest unit of measure → amino acid
Primary function → synthesis of enzymes, hormones, tissues
Surely this macronutrient has all the buzz in the fitness community. It seems like every type of food produced and packaged these days has a “high protein” version. Cereals, pastas, waffle mixes and energy bars are often marketed based on their protein content in reaction to the culture’s ever-growing awareness of the importance of protein in improving body composition.
After protein is digested, it is broken down into amino acids which are sent to the liver to be shuttled around to the cells for various functions. We keep a pool of amino acids for building necessary things like muscle fibers and connective tissue (tendons, bone, ligaments and cartilage), enzymes and immune system chemicals like antibodies that fight off infection. Eating enough protein and keeping up this amino acid pool ensures that we can maintain strong bones, healthy joints, good digestion and powerful immunity against illness. As with fats, our bodies do well with a wide variety of dietary protein (plant and animal) that make up the various kinds of amino acids. While it may be easy to get 100g of protein from a protein shake in one sitting, this isn’t necessarily the most beneficial way to provide your body with nutritional variety.
Almost all foods have some amount of protein, even broccoli. Just a few examples of plentiful protein sources are eggs, fish and seafood, meat, quinoa and brown rice, tofu and edamame, beans and lentils or dairy. If you sit down and track your macros, you may find that you are getting even more protein than you realized because it adds up throughout the day.
Protein does not provide the body with a lot of energy. For that, it needs fats and carbohydrates. This is why having a protein shake alone for breakfast before working out may not give you the boost of energy to keep you going. There is also a limit to the amount of protein a body can absorb and use at one time. We want to eat fats and carbohydrates along with our protein to slow down the uptake of amino acids and ensure the body is able to use all of that supply rather than needed to pee it out. This is also why protein is recommended to be eaten in smaller increments throughout the day to keep up a steady supply.
For the average individual trying to improve their body composition and for the high level athlete, a daily protein intake of 0.8-1.2 grams per pound of lean body mass is recommended. Especially when in a calorie deficit and trying to decrease body fat, getting enough protein in your diet helps you to maintain the muscle you already have, repair your tissue from hard training sessions and keep you feeling satiated longer throughout the day.
To understand which balance of macronutrients is right for us as humans, must look at the bigger picture of our individual goals and evaluate which macronutrients will contribute best to our energy requirements and our thriving brains. A macronutrient profile ideal for you is one that allows for adequate protein intake to ensure optimization of resistance training and an “energy-in” balance that helps you reach your body composition goals. Your macronutrient and calorie targets should contribute to thriving brain and hormone function to keep your body running at its highest capacity. But probably most important is finding a balance that allows for flexibility with food choices so that you can maintain adherence to your nutrition consistently over a long period of time. When all is said and done - aim for your goals, but enjoy the journey!