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Macronutrients and Their Individual Functions Within The Body

Macronutrients is one of the most popular terms in the nutrition space, and I’m sure you’ve come across it at one point or another.

And if so, you’ve also probably heard of the two common nutritional protocols surrounding it – if it fits your macros and flexible dieting. Both of them are based around the idea of tracking your macronutrient intake and aiming for specific numbers.

Today, we’ll take a look at what macronutrients (macros) are, what their purpose is within the body, and how they impact our fitness efforts.

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What Are Macronutrients?

Macronutrients are the components which make up the food we consume. And, as their name suggests, we need large amounts of them to sustain ourselves. This is primarily because, unlike micronutrients (vitamins and minerals), macros carry an energetic value – each gram contains a certain amount of calories. Protein and carbs each have four calories per gram, and fats have nine.

There’s also a fourth macro, alcohol (or ethanol), which has about seven calories per gram. Though alcohol is not critical for good health, and we don’t need to consume it to function and stay healthy. It’s only classified as a macro because it carries an energetic value and can theoretically provide us with the calories we need to stay alive.

But since alcohol isn’t essential, we’ll mostly ignore it today. Now, let’s take a look at the three main macros – fats, proteins, and carbs.

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Dietary Fats – Not The Boogeyman After All

Dietary fats are organic molecules made from carbon and hydrogen. Based on the structure of each particle, we can determine what type the fat is. The three main ones are polyunsaturated, saturated, and monounsaturated.

Each type of fat also has specific roles within the body, and we need them in adequate amounts to function properly and stay healthy (much to the dismay of some “health gurus” out there).

Some of the fat’s main functions involve hormonal synthesis, brain and metabolic health, cell and pain signaling, blood clotting, control of inflammation, immune system function, and the absorption of nutrients such as vitamins A and D.

In some human studies, dietary fats have been shown to play an essential role in nerve signaling within the brain.

Now, it’s important to point out that the fat source is also essential. Avocado, whole eggs, fatty fish, natural oils, full-fat dairy, and nuts are all great sources.

The ones you should avoid are those present in highly-processed foods such as margarine, which have been shown to contribute to numerous health problems, including heart disease.

As far as the intake goes, research is mostly in agreement that we should consume between 0.3 and 0.6 grams of fat per pound of body weight. That is, if you weigh 150 pounds, that will come to be about 45 to 90 grams per day. 

But, so long as you’ve got a healthy fat source at each meal, you should be okay with the total intake.

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The Critical Importance of Protein 

Dietary protein is arguably the most popular of the trio and has gained the praise of professional athletes and meatheads alike. And even though most people associate protein with muscle growth, its effects within the body expand far beyond the extra few pounds of muscle.

You see, protein is made of amino acids which act as the building blocks of living tissues and serve multiple functions within the body. Amino acids come in two categories – essential (those the body cannot create itself) and inessential (those the body can form on its own). There’s also a third sub-category – conditionally essential. These are the amino acids which the body can typically form on its own, but may not be able to do in specific situations – such is the case with glutamine in burn victims.

Now, as you consume protein, your body breaks it down to the usable amino acids which then contribute to the plasma pool of amino acids (a sort of storage for amino acids). 

The plasma pool is then able to quickly offer amino acids for different processes within the body, including cell formation, muscle repair, hormone and neurotransmitter synthesis, and much more.

Some of the protein’s other functions include the maintenance of tissues (organs, skin, bones, connective tissues, etc.), the transportation of substances within the body, muscle repair and growth, and the creation of antibodies, among other things.

So, even if your goal isn’t to get as muscular as possible, you still need enough protein every day. A good rule of thumb is to consume between 0.7 and 1 gram of protein per pound of body weight. For a 150-pound person, that comes out to be between 105 and 150 grams daily.

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Carbs – Functions, Structure, Dosage, and Important Considerations

Carbs, also known as the primary source of energy for the body, come in two primary forms – simple and complex.

Simple carbs are those which a shorter structure that get broken down into usable energy quickly. Think candy, cereal, table sugar, bananas, and more. Such carbs also have a higher glycemic index (GI).

Complex carbs are those with a longer structure that take more time for the body to break down into usable energy – think whole wheat and grains, potatoes, quinoa, oats, corn, legumes, and more. Such foods have a lower> glycemic index.

No matter what type of carb you consume, it then gets broken down into simple sugars for energy. These sugars are then transported to the liver and muscles for storage (in the form of glycogen), and some are left circulating your blood to provide fuel as needed.

Now, contrary to popular belief, there are no ‘bad’ or ‘good’ carbs. The primary difference is in their glycemic index and their effects on insulin. Fast-digesting carbs lead to a spike in insulin, a sudden rise in energy, and often lead to a crash.

Slow-digesting carbs lead to a more gradual rise in insulin, a steady stream of energy and no crash.

But, it doesn’t mean that slow = good and fast = bad. Both types of carbs have their roles within the body, especially when physical performance is involved. For example, fast-digesting carbs are great for pre and intra-workout snacks to supply you with energy for the physical work. They also work great after a workout to kickstart the recovery process and begin replenishing lost muscle glycogen fast.

Slow-digesting carbs are an excellent choice for every meal of the day because, as we covered, they provide us with a steady stream of energy.

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