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Carbohydrates: What You Need to Know

Updated: Mar 6, 2023


I always find it interesting when people say "I'm on a low-carb diet." What does that mean? Does it really mean low-carb? Or, does the person even understand what carbohydrates really are? If you think of carbohydrates as pasta, or breads, pastries, and pies. Then, it kind of makes sense that if you're cutting down on fats and sugars which are combined with carbohydrates and have excess calories you may feel the need to cut down on carbohydrates. However, you need to understand that carbohydrates are also fruits, vegetables, and grains that have a wide array of nutritional benefits.

Carbohydrates really should be the main fuel that goes into your body. If you think of your stomach as an oven that controls your heat and your fuel, carbohydrates are the leaves, kindling and small logs that goes into your body. They keep your metabolism going by adding fuel and creating heat. This includes sugar which is always needed, just not in excess.

I think of the small pieces of wood that go into the stove or fireplace as your carbohydrates. So, whenever I hear of low-carb diets and people trying to cut out carbs out in favor of more protein or fat, I'm not sure they understand that protein is the building element. Eating protein is like adding metal to a fire. It is not a fuel. However, protein is the macro nutrient that helps you get bigger and repair tissue. Fats are a great energy source but they are slow to burn. They have move calories per gram than carbohydrates or proteins which is something to be aware of for weight control.

Most food have a combination of carbohydrates, fats, and proteins. It's just that one macro-nutrient might be more dominant than another. For example, something that's a pure sugar is a carbohydrate but it probably doesn't have protein or fat component. I think about pure sugar like maple syrup. Those carbohydrates add fuel. But, it’s similar to adding newspaper to the fire. It’s great to get the fire started but there should be more substance within the fire to sustain it. Its difficult to keep up with the flare up and burn out of newspaper only in a fire. Too much sugar as a fuel source is the same. Complex carbohydrates with fiber add that substance. Sticking with the analogy, fats would be like large insulating material that would burn slower and provide a lot of energy. Protein on the other hand may be less of a fuel source like metal that may eventually burn but very inefficiently.

You need to understand that a lot of vitamins and minerals are in carbohydrates. They should not be thought of just your pastries, pies and breads. These things might have a high fat and sugar components. Fruits, vegetables, greens and grain are carbohydrates. They should, typically, be your main fueling source for your body.

Then, protein is something that you can vary based on the amount that you need. It depends on how much growth and repair you require. If you're an athlete and you're constantly trying to build muscle or repair a muscle, you're going to need more protein. And, if you're sedentary and you're already as large or larger than you want to be, you likely are not trying build and repair. Therefore, you don’t require as much protein.

Fats are a very dense energy source but they don't burn as efficiently as carbohydrates. They have more than twice the number of calories per weight. Each one of these macro nutrients have their place. This should help you understand that carbohydrates should have the largest place in most diets.


The National Academy of Sports Medicine (NASM) explains that “the primary role of dietary carbohydrates is to provide energy for the body.” Any excess carbohydrates not used for immediate energy production can be stored as glycogen within the muscle and liver. Because the liver is capable of releasing glucose into circulation, it helps regulate blood glucose and insulin metabolism, which helps avoid or manage diseases like diabetes and metabolic syndrome. Should there be additional carbohydrates, it is possible for this excess (i.e., beyond what the body can store as glycogen) to be converted to fats called triglycerides. Given this effect, carbohydrates could play a minor role in indirectly regulating some fat production. Furthermore, balanced levels of glucose and insulin also assist with regulating circulating levels of other hormones like testosterone and the thyroid hormones.”

This further illustrates that carbohydrates are the fuel that you should be putting in your body rather than restricting them or misunderstanding what they are and their role in favor of low carbohydrate diets.


The National Library of Medicine states, “there is no one-size-fits-all amount of carbohydrates that people should eat. This amount can vary, depending on factors such as your age, sex, health, and whether or not you are trying to lose or gain weight. On average, people should get 45 to 65% of their calories from carbohydrates every day. On the Nutrition Facts labels, the Daily Value for total carbohydrates is 275 g per day. This is based on a 2,000-calorie daily diet. Your Daily Value may be higher or lower depending on your calorie needs and health.” Carbohydrates are a very broad category of macronutrients. Rather than limit carbohydrates for weight loss or other reasons, understand that “you do need to eat some carbohydrates to give your body energy. But it's important to eat the right kinds of carbohydrates for your health:”

In the China Study by T Colin Campbell and Thomas Campbell, they state “there is a mountain of evidence to show that the healthiest diet you can possibly consume is a high-carbohydrate diet. It has been shown to reverse heart disease, reverse diabetes, prevent a plethora of chronic diseases, and yes, it has been shown many times to cause significant weight loss.” The carbohydrates should be consumed in their complex, unprocessed, form to get the most benefit.

In How Not to Die, by Dr. Michael Greger, he cautions to look for code words including multigrain, stone-ground, 100% wheat, cracked wheat, seven-grain or bran, since they are refined products stripped of their fiber. He instructs to use a five to one ratio. Carbohydrate weight should not exceed five times the weight of the dietary fiber content.

USDA has the following recommendations for carbohydrates that are fruits, vegetables and grains.

Fruits: These are general recommendations by age. Find the right amount for you by getting your MyPlate Plan.

Daily Recommendations*

Toddlers 12 to 23 months½ to 1 cup

Children 2-4 yrs 1 to 1½ cups 5-8 yrs 1 to 2 cups

Girls 9-13 yrs 1½ to 2 cups 14-18 yrs 1½ to 2 cups

Boys 9-13 yrs 1½ to 2 cups 14-18 yrs 2 to 2½ cups

Women 19-30 yrs 1½ to 2 cups 31-59 yrs 1½ to 2 cups

60+ yrs 1½ to 2 cups

Men 19-30 yrs 2 to 2½ cups 31-59 yrs 2 to 2½ cups

60+ yrs 2 cups

Vegetables: These are general recommendations by age. Find the right amount for you by getting your MyPlate Plan.

Daily Recommendation*

Toddlers 12 to 23 months ⅔ to 1 cup

Children 2-4 yrs 1 to 2 cups 5-8 yrs 1½ to 2½ cups

Girls 9-13 yrs 1½ to 3 cups 14-18 yrs 2½ to 3 cups

Boys 9-13 yrs 2 to 3½ cups 14-18 yrs 2½ to 4 cups

Women 19-30 yrs 2½ to 3 cups 31-59 yrs 2 to 3 cups

60+ yrs 2 to 3 cups

Men 19-30 yrs 3 to 4 cups 31-59 yrs 3 to 4 cups

60+ yrs2½ to 3½ cups

Grains: These are general recommendations by age. Find the right amount for you by getting your MyPlate Plan.

Daily Recommendations*

Total Grains Whole Grains

in ounce-equivalents in ounce-equivalents

Toddlers 12 to 23 months 1¾ to 3 oz-equiv 1½ to 2 oz-equiv

Children 2-4 yrs 3 to 5 oz-equiv 1½ to 3 oz-equiv 5-8 yrs 4 to 6 oz-equiv 2 to 3 oz-equiv Girls 9-13 yrs 5 to 7 oz-equiv 2½ to 3½ oz-equiv 14-18 yrs 6 to 8 oz-equiv 3 to 4 oz-equiv Boys 9-13 yrs 5 to 9 oz-equiv 3 to 4½ oz-equiv 14-18 yrs 6 to 10 oz-equiv 3 to 5 oz-equiv Women 19-30 yrs 6 to 8 oz-equiv 3 to 4 oz-equiv 31-59 yrs 5 to 7 oz-equiv 3 to 3½ oz-equiv 60+ yrs 5 to 7 oz-equiv 3 to 3½ oz-equiv

Men 19-30 yrs 8 to 10 oz-equiv 4 to 5 oz-equiv 31-59 yrs 7 to 10 oz-equiv 3½ to 5 oz-equiv 60+ yrs 6 to 9 oz-equiv 3 to 4½ oz-equiv


Fiber is very interesting! It seems like a boring word that you might only associate to something that elderly people should be getting more of to have better health. However, what if fiber could be the key to better nutrition and even weight loss?

Dr Michael Greger’s website states “Less than 3% of Americans get even the recommended minimum adequate intake of fiber. That’s something we really have to work on.”

Joanne L Slavin, in “Dietary fiber and body weight” conclude that “the average fiber intake of adults in the United States is less than half recommended levels and is lower still among those who follow currently popular low-carbohydrate diets, such as Atkins and South Beach. Increasing consumption of dietary fiber with fruits, vegetables, whole grains, and legumes across the life cycle is a critical step in stemming the epidemic of obesity found in developed countries. The addition of functional fiber to weight-loss diets should also be considered as a tool to improve success.”

Derek C Miketinas 1 2, George A Bray 2, Robbie A Beyl 2, Donna H Ryan 2, Frank M Sacks 3, and Catherine M Champagne 2, in a paper published by NIH reach the following conclusion “Dietary fiber intake, independently of macronutrient and caloric intake, promotes weight loss and dietary adherence in adults with overweight or obesity consuming a calorie-restricted diet.”

NASM points out that “removing fiber can increase a food’s glycemic index (GI) score.” A GI score indicates how much a food raises your blood glucose. Processed foods that have removed the fiber such as cakes, cookies, candy and some breads have a high GI score. Whole foods such as vegetables and unrefined grains have a low GI score.

NASM shares that the “degree of processing and cooking” “alters GI scores in both directions. Separating nutrients from fiber during cooking (boiling) can raise GI scores while making starch more resistant via repeated heating or cooking can lower GI scores (e.g., reheating pizza where it becomes rubber-like).” And, “Presence of other nutrients (e.g., fiber, protein, or fats)—This slows gastric emptying and digestion, which lower the food’s GI score.” And, “Juicing simply adds a greater density of sugar because of the quantity of fruits and/or vegetables needed to make juice (1 piece of fruit = 4 oz of juice or about 120 mL) eliminates the fiber.”


The National Library of Medicine states, in “Is it safe to eat a low-carb diet?”, “Some people go on a low-carb diet to try to lose weight. This usually means eating 25g and 150g of carbs each day. This kind of diet can be safe, but you should talk to your health care provider before starting it. One problem with low-carb diets is that they can limit the amount of fiber you get each day. They can also be hard to stay on for the long term.”


The presence of adequate amounts of carbohydrates can spare the body’s need to catabolize (break down) muscle tissue

The body can use stored glycogen and body fat to fuel a workout. However, fat burns slowing and can therefore lead to the athlete feeling fatigued. “Hence, the need to continue consumption of carbohydrate calories while working out or racing” states Matt Frazier, No Meat Athlete

“Athletes can increase their glycogen storage significantly by eating carbohydrate rich meals soon after working out. This refueling can help you recover quicker, feel less fatigued from your workout, and prepare you better for your next workout” explains Matt Frazier in No Meat Athlete

Robert Cheeke, a plant-based body builder, and Matt Frasier, a runner and host of “No Meat Athlete” in the book “Plant Based Athlete,” share that they “believe that the reason for [their] success comes down to the fact that carbohydrate-rich foods contain more nutrients.” And, Robert Cheeke in Plant Based Muscle states the he consumes “roughly 70 percent of [his] calories coming from carbohydrates.”

Scott Jurek, in Eat and Run, emphasized carbohydrates as his main fuel and plant-based nutrition he credits with how well he recovers.

Arnold Schwarzenegger has been advocating for a plant-based diet with healthy carbohydrates for health and environmental reasons.

Greg McMillan, in “Running Nirvana,” encourages runners to “eat the rainbow.” Different colored foods provide different nutrients like beta-carotene in carrots, iron in leafy vegetables, and vitamin C in a lemon.

In “Running and Racing After 35,” Allen Lawrence and Mark Scheid, recommend “60 to 70 percent carbohydrates for endurance runners.” And, “carbohydrates in your diet should be mostly complex (found in grains, vegetables, fruits and past), since the sources of most complex carbohydrates also offer the most vitamins, minerals and fiber. Limit simple carbohydrates (sugars) to 10 percent of your caloric intake.”

In “Running Smart”, Mariska Van Sprundel, “the advice for well-trained runners is to start eating more pasta, white bread, and sweet jams and jellies three days before a (half) marathon” when discussing carb loading before an endurance event.

In “Burn the Fat, Feed the Muscle,” Tom Venuto gives credit to the term premium fuel. “Sports nutritionist Dr. Michael Colgan who calls carbs “premium fuel.” He states “carbs are your body’s preferred and most efficient energy source for intense training.” And, “if you cut carbs too much, your physical performance and even your mental sharpness usually take a nose dive,” since the brain needs glucose.


I hope this helps you understand carbohydrates better. Nutrition is complex and there is a lot more to learn for a more in-depth understanding of carbohydrates.

At this point, you should understand that carbohydrates should be considered the main fueling source. You should choose whole foods over processed foods. An easy way to make that choice is to ask yourself if the food has fiber. If it does, it is probably the better choice. I may want the cookie sitting on the counter next to the apple. However, if I make having more fiber the goal, then I should choose the apple.

That said, the answer to most questions is “it depends.” The choice you make should be determined by you and your doctor or nutritionist. It depends on the availability of foods at the time. Sometimes, a cookie is the best option. It could save you from being too low on fuel by giving you needed calories to burn.

The information above has helped me achieve endurance and strength goals even while I am getting older. Keep learning so that you can reach your goals too!


National Academy of Sports Medicine

“Burn the Fat, Feed the Muscle,” Tom Venuto

National Library of Medicine

Running Nirvana, Greg McMillan

No Meat Athlete, Matt Frazier

Running and Racing After 35, by Allen Lawrence and Mark Scheid,

Running Smart, Mariska Van Sprundel , “Fiber Intake Predicts Weight Loss and Dietary Adherence in Adults Consuming Calorie-Restricted Diets: The POUNDS Lost (Preventing Overweight Using Novel Dietary Strategies) Study” by Derek C Miketinas 1 2, George A Bray 2, Robbie A Beyl 2, Donna H Ryan 2, Frank M Sacks 3, Catherine M Champagne 2

“Dietary fiber and body weight”, Joanne L Slavin 1

National Library of Medicine

National Center for Biotechnology Information

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