Understanding Macros: Protein, Fat, and Carbs

Diet and weight loss culture has made nutrition confusing. We want to break down macronutrients (or macros for short) so you can understand your body’s fuel sources better.  Your body has three main types of macronutrients: carbohydrates, proteins, and fats. Carbohydrates and fats are your main fuel sources. Fats also serve to balance hormone levels and break down and assimilate nutrients. Proteins are the building blocks for your muscles and to repair body tissues.  1. Carbohydrates (with some knowledge about fiber) Carbohydrates are the main energy source of the body. There are chains of small, simple sugars that are broken down and enter the body as glucose. Glucose is essential for the body, as it is the preferred source of energy to the brain, heart, and central nervous system.  Carbohydrates are vilified as public enemy number one and are accused of being the root of obesity, diabetes, heart disease, and other diseases. Eating less carbs doesn’t inherently make you healthier. People will switch out beans for bacon, or fruit for sugar-free and low carb processed foods. There is nothing wrong with carbohydrates and most of the world relies on them as their main energy source.  There are two types of carbohydrates: simple and complex. Simple carbohydrates are carbs that your body can break down into glucose and burn as energy almost immediately. High doses of simple sugars can cause sugar spikes and crashes, while small doses can help give an immediate energy boost.  Complex carbohydrates are carbs that your body needs to digest and slowly break down. They’re converted into simple sugar over time as your body metabolizes the carbs. Vegetables, rice, and bread are complex carbs. Not all carbs are created equal, even in simple carbs. The fiber and micronutrients in them determine how they are processed. A banana and a Kit-Kat are both simple carbs, but the banana had more fiber, more nutrition, and can cause less of an insulin spike. Fiber is an extremely important nutrient that we get from carbohydrates. Fiber helps slow down the process of food into sugar, making there less of a chance for a blood sugar spike and crash. If we severely restrict carbohydrates, we would not be able to meet our fiber needs. All naturally fiber rich foods are also rich in carbohydrates. The average U.S. intake of fiber is around half of what is recommended. Studies have shown that individuals with high fiber intakes appear to have lower risks of coronary heart disease, stroke, diabetes, hypertension, and obesity. (1)  2. Fats It started in the 80’s when Doctors, nutritionists, and public health officials told us that fat was bad and caused weight gain and heart disease. Low fat diets and foods increased and yet that didn’t improve food choices or people’s health. Rather, marketed low-fat food labels seduced the public. Fats are our second energy source. They serve several very important functions in the body. Fats are a store of energy. When your body needs more energy than it has glucose, it breaks down fats. Fat also helps your body process vitamins and nutrients. They also provide essential fatty acids (EFA).  Low fat diets often leave people feeling hunger and not satisfied. Fat burns slowly for energy, keeping you filled for longer because fats tend to slow down digestion.  Women also need to maintain a certain level of fats in their diet to maintain their hormonal balance.  There are many kinds of fats. The so-called “unhealthy fast” are trans-fats and too many saturated fats. These tend to be found in fast foods, hydrogenated oils, butter, and other processed foods. The “healthy fats: are monounsaturated and polyunsaturated fats. Nuts, avocados, oils are all natural sources. 3. Protein Protein is your body’s building blocks for tissues. Protein is generally not used as an energy source unless the body has no other option. It uses carbohydrates first, then fats, and finally breaks down muscles and uses protein if no other options are present. Your body contains thousands of different proteins, each with a unique function. Some proteins are enzymes, some are hormones, some maintain fluid balance, etc.  Protein in the American diet is usually with every meal, mainly with meats. This can give the impression that a meal isn’t complete without meat. Yet, most humans get enough protein in their diet. Vegetarians and vegans can also easily meet their protein needs.   Protein is important in maintaining muscle growth, but it is not an energy source.  Extremely high protein diets are most likely not necessary and protein in high quantities gets turned into glucose.   There is some data that suggests that both endurance and athletes have increased protein needs compared to inactive individuals. (2) Yet, overall the quantity of protein needed in a diet is debated.  These macronutrients are essential build blocks to your body’s fuel system. Make sure you have enough carbs to fuel your workouts, enough protein to build new muscles, and enough healthy fats to keep your body running smoothly! Resources:

  1. Anderson JW, Baird P et al. Health Benefits of Dietary Fiber. Nutrition Reviews. 2009 Apr;67(4):188-205

  2. Dunford M, editor. Sports Nutrition: A Practice Manual for Professionals, 4th Edition. American Dietetic Association, 2006.

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