Hey everyone! Today on the blog we are chatting about carbohydrates. I am adding this page to my site as an evergreen reference post to round out the fats and protein posts. I also hope to build upon this post in a future post about the keto diet.
But before I go into detail about what not eating carbs does to your body, I thought it was important to lay the groundwork to understand carbohydrates. Grab a bowl of your favorite carby food and read on!
What are carbohydrates?
Carbohydrates are energy nutrients that are composed of monosaccharides. Carbo means carbon, and hydrate means water. ‘CHO’ is a commonly used abbreviation for carbohydrates.
Carbohydrates are one of the three macronutrients, along with fat and protein. Macronutrients provide energy (aka calories) to the body. Each gram of carbohydrate provides 4kcal. Protein also provides 4kcal/gram, and fats provide 9kcal/gram.
*Disclaimer: As always, this is general information intended for healthy adults. Your needs may vary based on medical status, lifestyle, or life-stage. Please never replace generalized health information you’ve read online with individualized clinical care
More Detailed CHO Science (skip if you don’t care):
Carbohydrates are subdivided into categories based on the number of sugar units present. Monosaccharides consist of one sugar unit. Glucose, fructose, and galactose are monosaccharides considered relevant to the human diet. Disaccharides are pairs of single sugars linked together. Disaccharides relevant to the human diet include sucrose (table sugar) lactose (found in milk) and maltose.
Glycogen, starches, fiber are considered polysaccharides – meaning they are compounds composed of chains of monosaccharide units.
Glycogen is the storage form of carbohydrates in humans and animals. You may have heard of “glycogen stores” in your liver; that’s stored carbohydrates. Starches are the storage form of carbohydrates in plants.
Fiber is indeed considered a carbohydrate. As mentioned in this post, fibers are different from sugars and starches as the body can digest nor absorb them, and thus they provide little, if any, energy for the human body.
There is an additional group of carbohydrates known as oligosaccharides, which consists of short chains of monosaccharides. Many FODMAPs are oligosaccharides. I will have a whole post on FODMAPS out soon.
What do carbohydrates do in the body?
Carbohydrates are the preferred source of energy for many bodily functions and provide fuel for all cells in your body.
Sugars and starches are broken down into glucose (sugar in your blood) and are used as energy. Your brain prefers glucose over other forms of energy (yes, your brain can run on ketones in a carb-starved state; however glucose is a fast and sure way to fuel your brain).
In the blood stream, glucose is taken to cells all over the body and undergoes a metabolic reaction process known as cellular respiration, which converts the sugar into an energy-carrying molecule known as adenosine triphosphate (ATP), which is used to fuel cellular processes.
So as you can see, carbohydrates fuel your body. They provide energy!
Carbohydrates can also be stored in various tissues including muscle tissue and the liver in the form of glycogen. During extended periods between meals (such as when you are sleeping), your body can tap into these stores, break down the glycogen, and utilize the stored carbs as fuel for essential body functions, such as breathing, digesting food, thinking, etc.
Glycogen stores protect your body from harvesting proteins in muscles when you need energy but haven’t eaten a recent meal. Considering your heart and diaphragm are muscles, preserving the body from metabolizing protein from muscles is protective and important. I am planning a full blog post about metabolism in starved/fasting states very soon, so stay tuned for that.
Fiber is also considered a form of carbohydrate, although fiber is not broken down in the body nor harvested for energy.
But that doesn’t mean it isn’t important: In addition to aiding satiety and helping bowel functions, fiber plays many important roles in supporting human health and preventing diseases such as type 2 diabetes, and cardiovascular diseases.
How many carbohydrates do you need?
The Institute of Medicine set an Acceptable Macronutrient Distribution Range for carbohydrate of 45-65% of total calories, with protein as 10-35% daily total calories, and fat as 20-35% daily total calories.
As you may notice, carbohydrates are recommended to make up a bulk of the human diet.
The USDA 2015-2020 guidelines suggest set the carbohydrate RDA for healthy adults as 130 grams of carbohydrates per day. This is the amount required to provide the brain with enough glucose to function properly. As your daily activities often require more activity than brain function (ie, breathing, digesting food, walking if that’s available to you, exercise, chores, etc) then you need more carbohydrates to fuel those activities.
That’s why the AMDR is 45-65% calories. For a person consuming 2,000 calories a day, the ideally 900-1,300 calories should come from carbohydrates.
Sources of Carbohydrates:
Fruits, vegetables, grains and grain products, and legumes are natural sources of energy-yielding starchy carbohydrates and dietary fibers. A healthful diet includes foods from these groups to make up the bulk of their carbohydrate intake.
Cow’s milk dairy products are also rich in carbohydrates. Lactose, as mentioned above, is a carbohydrate. Each cup of milk contains roughy 12 grams natural sugar in the form of lactose.
Added sugars are also considered carbohydrates. Major sources of added sugars include soft drinks, candy, cakes, cookies, pie, cobblers, desserts, etc and may go under the names of brown sugar, sweetener, corn syrup, fructose, glucose, dextrose, high-fructose corn syrup, honey, lactose, maltose, molasses, raw sugar, sucrose, etc.
Current USDA dietary guidelines suggest consuming no more than 10% total daily calories from added sugar (not including natural sugars from foods such as fruit, dairy, and vegetables).
So Should I Eat Carbohydrates?
Although low-carb diets are popular, for most healthy people (some medical conditions aside), a healthful diet includes ample carbohydrates.
Preferably, carbohydrates should come from whole grains (such as oatmeal, barley, quinoa, etc) and whole grain products (such as 100% whole wheat or sprouted breads, whole grain cereals, etc), fruits, starchy vegetables (such as carrots, potatoes, etc), and legumes.
As you may have noticed, many of the above mentioned sources of carbohydrates are healthful, and rich sources of a variety of micronutrients, plant-compounds, and dietary fiber. They are also satiating, and heck – delicious!
Unless you have one of a few specific medical conditions and are under the direction of a medical professional to avoid carbs, I see no reason to avoid them, especially from whole grain, starchy vegetables, fruits, and legume sources.
When it comes to added sugars, it is advisable to not overdo it. However, if you ask me, it is also not necessary to eliminate added sugars completely. The concern with over-consuming added sugars is that by doing so you typically displace nutrient-rich food, which obviously isn’t ideal if done most of the time. But the occasional cupcake is fine, in my opinion ;-).
Take Home Points:
Carbohydrates are the body’s preferred source of energy and should make up 45-65% of the human diet and are not to be avoided. Strive to select whole grain and whole grain products, fruits, vegetables, and legumes to make up a bulk of your carbohydrate intake most of the time.