What Do Carbs, Proteins, and Fats Actually Do? A Breakdown of Macronutrients

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What Do Carbs, Proteins, and Fats Actually Do? A Breakdown of Macronutrients

Just when you think you are eating the right things, your friend quickly points out that you are eating way too many carbs.  Then again, what do they know, they have been on a no-carb, high protein diet for a few weeks now?  Another friend says that protein shakes are what you are missing.  So now who are you to believe? The list goes on...



Related: Top 10 Signs & Red Flags of a Bad Personal Trainer 

The whole concept of diets calling for low-carb, no-carb, high protein, low fat, and so on (and so on) can make your head spin.  Everyone seems to have a different idea about what it means to eat healthy, what is the proper way to diet, how to lose weight the "correct" way, etc.  The bottom line is — before you embark on a journey to lose weight, it is important to first understand how your body uses macronutrients (carbohydrates, protein, and fats).  And, most importantly, keep in mind that — science is science.

Since carbohydrates have found themselves in the spotlight the most lately, let's start there.  While some diets promote counting carbs, or eating low-carb or even eliminating carbohydrates across the board to achieve weight loss, what is the real deal? The truth is, while there are different types of carbohydrates (some "good" and some "bad"), they are the body's main source of fuel.  For this reason alone, it is certainly important to keep them in your diet.  The big debate, then, becomes how much (and what kinds of carbohydrates) to eat.

A wotthwhile read: Is counting macros necessary? Pros and Cons of Tracking Macros

Carbohydrates are made up of sugar molecules, which are then transformed in your body to fuel.  Without carbohydrates, your body will break down muscle tissue instead to act as fuel, which will counteract any of your efforts working out.  When it comes to carbohydrates, there are two kinds to consider — simple and complex.  Simple carbohydrates are found in things like table sugar, soda, and candy.  These are the ones that are considered “bad carbs” when looking to eat better.  Complex carbohydrates, on the other hand, include things like oatmeal (try this delicious chocolate & berry overnight oats recipe), brown rice, whole grain bread, and apples.  Complex carbohydrates are higher in fiber, thus more filling and taking longer to digest.  These are considered the “good carbs” when it comes to healthy meal planning.  Not only will complex sources help with appetite control, but the fiber helps reduce blood sugar spikes, promotes bowel regularity, and lowers cholesterol.  Fiber rich fruits and vegetables fit into this category as well, making them great additions to any diet.   When it comes to fitting carbohydrates in your diet, the recommended amount will vary depending on your activity level, what types of foods you prefer, what proteins and fats you eat, and how your own body breaks them down.

When it comes to protein, it seems that almost everyone is on board.  Protein seems to be the one macronutrient everyone can’t get enough of these days.  From shakes to bars to chips to loading up on grilled chicken, protein seems to be the one nutrient everyone is willing to go "all in" on.  Protein can be found in many foods, most obviously and commonly in food like fish, eggs, red meat, beans, cheese, and chicken. The good news is that protein is used by your body to build and repair damaged muscle, as well as bone, hair, skin, and other parts of the body.  Protein is made up of smaller molecules called amino acids, and is categorized as complete or incomplete proteins, based on the amount of amino acids it contains.  The complete type will contain the nine essential amino acids, which your body cannot make on its own, while the incomplete will not.  By eating a diet that is made up of various types of proteins, your body can meet its complete protein needs.  

Related recipe: Slow cooker beef with root veggies Prefer a meat free dish? Try this Protein Power Quinoa Egg Breakfast or Nutrition Powerhouse Beet Veggie Burger

Fat is another nutrient that has gotten a bad name in the world of dieting, from conversations among dieters to those on social media.  Many people assume that eating fat makes you fat, plain and simple.  This theory led to a whole market place of fat-free and low-fat foods of all kinds, with consumers buying these in droves.  The problem is that most of these products that are devoid of fat, are then loaded with sugar, in an effort maintain taste and consistency.  So, getting the facts straight — while there are good and bad fats, fat itself is important to the body.  In fact, the American Heart Association recommends a low-fat diet, which is actually 25-35 grams of fat.  

Fat plays a critical role in the body in many ways including: aiding in digestion, controlling body temperature, coating for nerves, and serving as a substrate for many hormones.  When it comes to fats one needs to understand the differences between monounsaturated, polyunsaturated, saturated, and trans fats.  Monounsaturated fats can be found in foods like olive oil, avocados, and nuts like almonds and walnuts.  These monounsaturated fats help to lower bad cholesterol and raise the good cholesterol.  This type of fat has also been found to help fight weight gain by reducing body fat.  Polyunsaturated fat is found in foods like sunflower oil, seeds and salmon.  These fats contain the essential fatty acids omega-3s and 6s, which cannot be made by the body and thus need to be ingested for your body to function normally.   Saturated fats, the ones that come from animal fats such as red meat, cheese and whole milk are the ones that people should eat sparingly.  While they have been linked with obesity and heart disease when taken in excess, many studies show that having them in small amounts allows the body to be more satiated, leading people to consume less calories.  The last group of fats, known as trans fats, are the ones to be considered the most unhealthy. Trans fats are found in french fries (try these homemade fries instead), chips and fried foods. These fats have been shown to not only increase your bad cholesterol but they also decrease your good cholesterol.  

Understanding the science behind carbohydrates, proteins and fats will allow you to learn to balance your diet to meet your needs.  It is clear that all three play a significant role in your body and being healthy means to incorporate all three.  Paying attention to fueling your body, listening to hunger cues, managing your caloric intake and finding the right balance of these macronutrients will lead to success. 


M Mittler, MS Registed Dietitian