Carbohydrates are not an essential macronutrient, meaning that we don’t need to consume them to survive. Our bodies can make glucose even if we don’t consume dietary carbohydrates. However, just because we don’t need to consume carbohydrates to survive doesn’t mean that we shouldn’t eat any carbs at all.
Carbohydrates are the main source of energy in living organisms. Our brains, red blood cells, and central nervous system require a continuous supply of glucose (one of three types of single sugar molecules) since they use it as their primary fuel source. Our bodies also prefer to utilize carbohydrates as fuel for exercise.
In addition, carbohydrates can prevent muscle (protein) from being broken down to be used as a fuel source during exercise, improve our digestive health and sleep quality, and can even make us feel more satiated through its effects on leptin, a satiety hormone. Furthermore, carbohydrates decrease cortisol levels, a stress hormone, via insulin, and help support proper thyroid hormone function, which directly affects our metabolisms. Sufficient carbohydrate intake may also be linked to reproductive health in women.
Fiber is the part of a carbohydrate that can’t be broken down all the way by our digestive system. There are two types of fiber: soluble and insoluble fiber.
- Soluble fiber adds substance to food and slows down our digestion. If you ever have issues with constipation, try reducing your soluble fiber intake and increasing your insoluble fiber intake. Examples of food with soluble fiber include nuts, peas, oats, bran, barley, seeds, beans, and lentils.
- Insoluble fiber adds bulk to food and can increase the speed of our digestion. Examples of foods with insoluble fiber include wheat bran, vegetables, and whole grains.
Sufficient dietary fiber intake:
- improves blood glucose and insulin sensitivity
- lowers cholesterol
- improves blood lipids
- may aid in weight loss
- may increase satiety
- supports a healthy gut microbiome.
Fiber is a “goldilocks” micronutrient. You don’t want too much, and you don’t want too little. Too high of a fiber intake can cause GI issues and can bind essential vitamins and minerals, preventing them from being absorbed by our bodies. If we eat a low fiber diet, we’re missing out on fiber’s many important health benefits. We suggest that people aim to consume 12-15g of fiber per 1000 calories. For the general population, this amounts to ~38g of fiber for men, and 25g of fiber for women.
Additional sources of fiber rich foods include berries (raspberries, blueberries, strawberries), apples, pears, artichoke, green peas, avocados, whole wheat products, quinoa, oats, nuts and seeds, beans, and lentils.
Glycogen is the readily available, storage form of glucose in the human body. Our livers can store ~80-100g (sometimes up to 160g) of glucose in the form of glycogen, and its main purpose is to help maintain our blood glucose levels. Our muscles can store ~300-700g of glucose in the form of glycogen, and this store of glycogen is utilized as our main source of energy during exercise. Our blood generally contains 0.9g glucose/liter of blood at any given time. This amounts to nearly 2000 calories of stored carbohydrates in our bodies alone!
For every 1 gram of glycogen stored, we store 3-4g of water. Let’s say we hypothetically have 90g of glycogen in our livers and 500g of glycogen in our muscle. That means we could store anywhere from ~1800-2400g of water in our bodies, which is 1.8-2.4kg or nearly 4-5.3lbs!
Why is this important? When you eat more carbohydrates, your body will naturally retain more water, which could cause the scale to rise. If you eat more carbs and see the scale rise immediately, don’t panic! It’s just water weight!
Recommended Dietary Intake
The Recommended Dietary Allowance for carbohydrates is minimum 130g. That amount is based on the amount needed to supply adequate glucose for the brain and nervous system without having to rely on ketone bodies from incomplete fat breakdown as a calorie source.
The Acceptable Macronutrient Distribution Range for carbohydrates is 45 to 65 percent of your total daily calories.
The amount of carbohydrates an individual should consume daily varies greatly based on their body weight, training volume and type, and goals.
- 1-4g/kg BW for health
- 2-6/kg BW for muscle gain
- 1-3g/kg for fat loss
- 3-12g/kg for sports performance
Recommendations for Athletes
- Low intensity or skill-based: 3-5g/kg BW/day
- Moderate exercise (~1hr/day): 5-7g/kg BW/day
- Endurance (~1-3hrs/day): 6-10g/kg BW/day
- Extreme exercise program (>4-5hrs/day): 8-12g/kg BW/day
Carbohydrates can be consumed in all meals and the amount included in each meal will vary person to person depending on goals and preferences. However, individuals seeking to improve their sports performance or who want to feel energized during their workouts can consume lower fiber, easy to digest carbohydrates in their pre-workout meal. Carbs can also be consumed after moderate to hard, long workouts to replenish depleted glycogen stores.
Sources of Carbohydrates
We believe that the majority of a person’s carbohydrate intake should come from complex carbohydrates. These carbs consist of hundreds and even thousands of sugar molecules bonded together. Due to their structure and fiber content, they take longer to break down and digest. They are also rich in vitamins and minerals. For many, they make it easier to maintain a healthy weight, and can prevent certain conditions such as Type II Diabetes and cardiovascular disease. Examples include starchy vegetables, fiber-rich fruit, legumes, and whole grain products.
In fact, dietary guidelines recommend that half of our grains come from whole grains and that we should limit our intake of refined grains, especially those with excessive added sugars. Whole grains provide more fiber, minerals, trace minerals, vitamins, carotenoids, and other phytochemicals, which are contained in the bran and germ of grains. At least two servings of whole grains per day can reduce the risk of cardiovascular disease, diabetes, metabolic syndrome, some cancers, and obesity. Look for “whole” as the first word on the ingredient list!
In addition, we recommend at least one cup of vegetables in two meals a day. For many, including vegetables in most meals and snacks is a great goal to work towards. Vegetables are low in fat and calories and rich in vitamins, minerals, and fiber. If you’re able to throw in a cup of fruit at least once a day, even better!
Vegetables: artichoke, arugula, asparagus, beets, bell peppers, bok choy, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, celery, collard greens, cucumber, eggplant, green beans, kale, lettuce, mushrooms, okra, parsnips, radish, romaine, peas, sprouts, swiss chard, tomatoes, corn and corn products.
Fruit: apples, bananas, berries, oranges, papaya, mango, peaches, pears, plantains, plums, kiwi, grapes, cherries, apples, oranges, figs, prunes, and melon.
Potatoes (sweet potatoes, reds, rustic, murasaki, yukon, etc.), along with squash, such as delicata, pumpkin, acorn, butternut, spaghetti, and kabocha squash.
Whole grain products such as quinoa, oatmeal, millet, bread, brown or wild rice, buckwheat, bulgur, amaranth, farro, and barley.
Legumes such as lentils, navy beans, kidney beans, black beans, chickpeas, and split peas.