Carbohydrates: what are they, exactly, and should we be eating them? Learn all about carbs and how to the best ways to include them in your diet here!
Carbohydrates totally get a bad wrap these days. Some of the most popular diet trends promote going gluten free, grain free, or just eliminating as many carbs as possible.
As an RD, people often ask my opinion on these low carb diets, such as the paleo, ketogenic, or carnivore diet. While everyone is different, my answer is almost always don’t bother. We’ll get into the details soon, but any diet that restricts plant-based, fiber-rich foods is almost certainly not beneficial to our health in the long run.
In this post, you’ll learn all about carbohydrates. Put your science caps on! First, we’ll go over what carbs are. We’ll dive into how they are digested, used, and stored by the body. You will also learn why carbs are an important part of a healthy diet and which ones are best to eat.
What are carbohydrates?
Carbohydrates are the naturally occurring sugars, starches, and fiber found in foods. All carbs are made up of individual sugar molecules. The smaller sugar molecules are linked together in larger chains to form starches and fiber. Carbohydrates are one of the macronutrients – the other two are protein and fat.
Carbohydrates are the preferred source of energy for all the cells in our bodies. More specifically, our bodies rely on the simple sugar glucose for energy and body processes. When we don’t get enough glucose in the diet, we turn to ketone bodies for fuel (which is the basis of the ketogenic diet).
Food sources of carbohydrates
Carbs exist in several types of food:
Beans and legumes
Refined products, like bread, pasta, and pastries
Carbohydrate digestion, absorption, and storage
Most carbs we eat contain long chains of sugars, starches, or fiber. In order for our bodies to absorb carbohydrates for use as energy, they must be broken down into simple sugar units (mostly glucose). The digestion process does this with help from enzymes in our mouth, pancreas, and intestines.
Glucose then gets absorbed into the bloodstream from the intestines. First, it stops at the liver, where it is stored in the form of glycogen, or sent back into the blood to be transferred to other cells in the body.
Carbohydrates and insulin
We need to maintain tight control of our blood glucose levels. Too much or too little glucose leads to dangerous health consequences. In order to maintain a normal blood glucose level, we need the hormone insulin.
Carbs and insulin have an vital relationship with each other. Our bodies are super smart – when our blood glucose levels rise after we eat, the pancreas secretes insulin. Then, insulin signals our cells to remove glucose from the blood to use as energy. Once cells get their fill of energy, insulin signals the liver and muscle cells to store any leftover glucose. The presence of insulin in the blood is totally normal – it simply means you’ve recently eaten something with carbohydrates.
On the other hand, if your blood glucose level significantly drops, another hormone called glucagon signals the liver to break down stored glycogen into glucose. Then, this glucose travels into the blood to raise blood glucose levels to a safe range. This will happen when you haven’t eaten in a while, so there is limited glucose available to the cells for energy.
Glycogen stores get depleted after several hours of not eating, such as overnight while we sleep. It’s important to replenish glycogen stores with dietary carbs. If we drastically limit food intake (including carbohydrates), the body will start breaking down protein for energy. If dietary glucose is severely restricted, the body releases fatty acids to be used as ketone bodies for energy.
Note that this process is impaired when someone has diabetes. With diabetes, your body either does not produce insulin, or isn’t able to use insulin efficiently, leading to chronically elevated blood sugar when left untreated.
Balancing blood sugar levels
As mentioned before, blood sugar is tightly regulated to remain in the range of ~70-140 mg/dL, for people without diabetes. Your blood sugar will be on the lower end of that range in a fasting state, and higher after eating something with carbs.
Balancing blood sugar is another trend in the wellness world. But what does this actually mean, and how do we accomplish it? For people without diabetes, the body naturally balances blood sugar levels using the hormonal mechanisms that include insulin and glucagon, mentioned above.
The best way to keep this process running smoothly is to eat balanced meals which contain all the macronutrients. When we eat carbs (ideally some that have fiber) with protein and fat, digestion slows down, so glucose is released more slowly and steadily into the bloodstream. You don’t need complicated methods or fancy supplements to balance your blood sugar, just a variety of real foods!
Fiber digestion and benefits
Fiber is a type of carbohydrate that is not digested by the human body. Even though we are unable to extract and absorb nutrients from fiber, it’s an extremely important part of the diet. Fiber is only found in plant foods, including vegetables, fruits, legumes, beans, nuts, seeds, and whole grains. We need 25 (women) to 38 (men) grams of fiber a day.
Some health benefits of fiber include:
Keeps us regular by speeding up digestion and increasing stool bulk.
Weight management – fiber is filling and fiber-rich foods are low in calories.
Lower cholesterol levels – foods with soluble fiber form a gel that binds to the “bad” LDL cholesterol and draws it out of the body.
Helps control blood sugar levels – fiber, particularly soluble fiber, slows the digestion and absorption of glucose and sugars.
Promotes gut health – Fiber in our diets cannot be digested and absorbed by humans, but the healthy bacteria (probiotics) that live in our guts rely on dietary fiber for food and fuel. High fiber diets promote probiotic diversity, abundance, and health.
Reduced risk of chronic disease – Fiber is only found in plant foods. There is abundant evidence that diets high in plant based foods, such as the Mediterranean diet, reduce the risk of chronic diseases like cardiovascular disease and diabetes. Also, plant foods are rich in vitamins, minerals, and antioxidants, which keep us healthy and reduce inflammation.
Benefits of carbohydrates
Vitamins, minerals, and other nutrients: As you can see, carbs are a SUPER important, vital part of a healthy diet. Carbs are found in many of the planet’s healthiest, nutrient dense foods, like vegetables, fruits, and legumes. Along with eating carbs, we also get the amazing vitamins, minerals, and antioxidants that come along with them.
Energy: Without carbs, our cells don’t get the energy they prefer and utilize best. Imagine owning a car that takes high octane fuel. You would never willingly use a lower fuel grade on your nice car, so why do the same for your body?
Fiber and long term health: When we severely restrict carbs (such as in the ketogenic and carnivore diets) we also restrict fiber, which provides several important health benefits noted above. Restricting carbs and fiber-rich foods long term may have negative long term health consequences.
Best carbohydrates to include in your diet
Nutritionally, not all carbs are created equally. Carbs can be simplified into two categories – whole food carbohydrates and refined carbohydrates.
Whole food carbohydrates include whole, minimally processed foods. The foods in this category are vegetables, fruits, unsweetened dairy products, whole grains, beans, and legumes. Whole food carbs are generally higher in fiber and other nutrients and lower in calories than refined carbs.
Refined carbohydrates are any highly processed foods. Foods in this group include white bread, white pasta, baked goods and sugar sweetened beverages. Refined carbs are stripped of all the good stuff, including fiber and other nutrients.
Choose whole food carbohydrates most often. It’s best to include a variety of foods from each group! For example, try quinoa this week, and brown rice the next. Swap out your usual romaine lettuce for spinach or kale in your salads. Experiment with different types of beans and legumes when making vegetarian meals.
That being said, there is a time and place for ALL types of carbohydrates in your diet. Food provides so much more than fuel for our cells; it gives us pleasure, comfort, and community. As much as I enjoy cauliflower crust pizza, it will never take the place of gluten-filled, freshly baked pizza from my favorite restaurant.
It’s so important to honor your desires and cravings, whether they are for cucumber or garlic bread. I promise, it all evens out in the end, and when you’re eating enough of, and a variety of carbohydrates, you just won’t have the desire to binge or overeat the refined ones.
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