“Carbohydrates are bad”.

“Protein is healthy”.

“I’m going low carb to lose weight.”

Do any of these statements sound familiar to you? Unless you’re not a part of modern society, they probably do. The low-carb trend has skyrocketed in popularity in recent years, and a number of specific diets involve this approach as well, such as the ketogenic diet, and some versions of the Paleo diet.

Even for those not following a specific low-carb diet, many are becoming reluctant to buy high-carb foods, and they get a sense of uneasiness when they see that a certain product is high in carbohydrates. This stems mainly from recent media portrayals that carbohydrates are the main culprit of the obesity epidemic, diabetes, and other health issues. The idea of carbohydrates in refined flours and sugars having negative effects on all areas of health (which is obviously true) has been extrapolated to suggest that carbohydrates from all sources are bad, even fruits and starchy vegetables. In turn, people lump together sweet potatoes, quinoa, potatoes, rice, and so forth with candy, cookies, sugary cereals, etc., just because they all have carbohydrates.

Despite the obvious differences between these foods, many people are blindly following this dogma without having a scientific understanding for their own approach. Thus, the question remains…based on scientific evidence, are low-carbohydrate diets optimal for most people?”

 In this article, you’ll see a number of reasons to explain why the answer to that question is a resounding “No!”. Carbohydrates, from the right forms, are the cornerstone of a healthy diet. Neglecting them can lead to significant health consequences if not addressed appropriately. This is why I’m ultimately writing this article: to help you understand the major roles that carbohydrates play in a healthy diet. It is up to you what you decide to do with this information.

I take a stance on this issue using research from many different fields, including psychology, holistic nutrition, anthropology, and biology, using all of these to point to the idea that carbohydrates should not be neglected in the diet, and in most cases should make up a large percentage of one’s diet.  For the specific reasons as to why carbohydrates are healthy, read on below!

Fiber, Gut Health, and the Connections to Overall Health

To understand the importance of carbohydrates in the gut, it is important to see the connections between gut health and overall health. Your gastrointestinal tract is colonized by living organisms, called microbiota, and they drastically influence overall gut health. The good ones are called probiotics, and in order to feed these guys, they need prebiotics. And the best way to get them prebiotics is from fiber, which comes exclusively from plant foods. And most plant foods are predominantly carbohydrate-based. Are you seeing the connections now?

Yet, unfortunately, many people are consuming far less fiber than our ancestors; we average around 20 grams per day compared to 50 to 100 grams per day for early humans (1). One of the main reasons for this is that many people eat primarily processed and refined carbohydrates, which are stripped of fiber and other nutrients. Additionally, a lot of people, especially those on low-carb diets, don’t eat enough plant foods in general, thus they don’t eat enough fiber.

In turn, a lack of fiber disrupts the gut microbiota (bacteria), which leads to a poorly-functioning GI system. And this eventually negatively affects all other bodily functions. Notably, it disrupts neurotransmitter production and overall brain health, immune health, and skin health. Furthermore, a lack of fiber and GI disruption are associated with increased diabetes, obesity, cardiovascular risks, and certain cancers (1) (2).

(These first two sources provide a great deal of information if you want more of the specifics on the mechanisms underlying all of these things. And see the diagram below that illustrates all of this).

Quality Matters!

This is why you need to feed your good bacteria with high-carb, high-fiber foods. And just in case you still thought you could eat unhealthy high-carb foods, that is not the case! Donuts, white bread, chips, candy and the like, provide nothing in the way of fiber or nutrients. Instead, the foods you should be eating are a wide assortment of fruits, vegetables, nuts, seeds, beans and legumes, potatoes, sweet potatoes, and whole grains.

Of course, don’t eat any foods in these categories that you are allergic or sensitive to. Other than that, if you eat these foods, you’ll be feeding your gut with quality nutrients, and thus you’ll be well on your way to restoring and eventually optimizing your GI tract.

In turn, eating this way can reduce obesity and diabetes, improve cognitive functioning, modulate immune function, fend off irritable bowel syndrome (IBS) and other GI disorders, improve liver health, improve cardiovascular functioning, and much more! (1) (2).  

Cortisol, Stress, and Inflammation

Another way carbohydrates are beneficial is that they can reduce stress. When blood sugar is too low, a state called hypoglycemia, cortisol increases to mobilize glycogen, so it can be turned into glucose and utilized by the body (3). Thus, if one is constantly under-consuming carbohydrates, and thus glucose, cortisol levels will remain elevated. This is especially true if the person is someone who exercises intensely, engages in a lot of mentally demanding tasks, and/or has a lot of other life stress, since all stress increases the demand for nutrients.

In turn, elevated cortisol over time can lead to many problems, such as thyroid issues; low testosterone in men and low estrogen and increased menstrual and menopausal symptoms in women; panic, anxiety, and depression; fatigue; impaired immune function; and unfortunately, many other problems (4).

Fortunately, increasing carbohydrates from whole-food sources decreases cortisol levels and also decreases physical and psychological responses to various stressors (3) (5). Additionally, high-quality carbohydrates are anti-inflammatory. Fruits, vegetables, whole grains, and so forth, all contain an abundance of antioxidants and other phytochemicals, all of which reduce inflammation, which in turn reduces stress on the body (5). So, if chronic stress is a problem for you, seriously consider increasing your carbohydrate intake.

Energy and Exercise

The primary role of carbohydrates is energy production. All carbohydrates eventually get broken down by the body’s metabolic processes into glucose, which is the body’s preferred source of fuel. This is because we have eaten a primarily carbohydrate, plant-based diet throughout our history, and have adapted to favor carbohydrate sources for energy.

Therefore, without enough complex carbohydrates in one’s diet, there will be a lack of sustained glucose, which can lead to decreased energy from the muscles and all other systems involved in exercise and other activities.

Those who engage in exercise of any kind, but especially long-duration exercise, such as distance running, should make sure they include enough carbohydrates to fuel performance.

Carbs Enhance All Forms of Exercise

Whether one engages in anaerobic or aerobic exercise, carbohydrates appear to be beneficial. Specifically, consuming a lot of carbohydrates before and during exercise improves performance, regardless if it is of short-duration at a high-intensity or of longer duration (1 to 2 hours or more) at a moderate intensity (6) (7).

For shorter-duration, higher-intensity exercise, carbohydrates enhance central nervous system functioning and can be broken down rapidly enough to supply the fast-twitch muscle fibers with glucose, whereas in longer-duration exercise, carbohydrates provide a steady stream of glucose for the muscles and all other involved systems (6). In either case, carbohydrates are beneficial.

Additionally, higher carbohydrate intake appears to be optimal for resistance training, leading to prolonged energy through one’s workouts. And higher carbohydrate intake is more conducive to building muscle, for a variety of reasons (8).

Finally, carbohydrates are better for recovering after exercise. Exercise is stressful, and that can be a good thing, as long as it is recovered from. And this is done by consuming carbohydrates, which increases glucose, and it also positively affects various hormones, which allow glucose resynthesis to properly take place, primarily in the muscles (6) (7) (8). The longer and more intensely one exercises, the more carbohydrates he or she will need to consume to properly fuel, maintain, and recover from the given exercise.

The main message is that carbohydrates taken before, during, and after workouts will increase performance and recovery, there’s just no question about it anymore.

Mental Health

I’ve talked a little bit about how carbohydrates can affect mood and mental health, but I want to go into this in a bit more detail. As a reminder, the body needs glucose for energy, but the brain actually requires a proportionately higher amount of glucose than the rest of the body, relative to its size. The brain is around 2 percent of one’s body weight, yet it consumes about 20 percent of the glucose! Thus, having enough fuel is vital for mental health.

Yet, I need to emphasize that processed, refined carbohydrates are one of the worst things to consume for mental health. They cause inflammation, rapidly increase insulin, disrupt the gut microbiome, and are related to diabetes and obesity, all of which increases the risk for anxiety, depression, and other mental health issues.

On the contrary, whole, unprocessed carbohydrates provide a steady stream of glucose for energy and help to regulate stress and inflammation, improve gut health, improve insulin sensitivity, and reduce stress, all of which should relate to better mental health (9) (10).

Specific Mechanisms

Specifically, decreasing stress and inflammation would improve mental health due to the decrease in inflammatory chemicals in the brain; this is vital since the brain is particularly susceptible to inflammation. Also, since there is a key relationship between the gut and the brain, restoring gut health would improve mental health. Fruits, vegetables, whole grains, and other healthy carbohydrates all appear to accomplish this, and it is no surprise that these foods are in high abundance in people with low depression rates (11).

Finally, specific compounds in carbohydrates can increase certain neurotransmitters in the brain. For example, when one eats carbohydrates, this causes an increase in insulin, which triggers tryptophan to enter the brain. In turn, tryptophan affects neurotransmitters, such as serotonin, which are related to improved mental well-being. Opposingly, diets too low in carbohydrates may increase depression due to the limited amounts of tryptophan, serotonin, and other important brain chemicals (12).

As you can see, there are many pathways in the body that are affected by carbohydrates, all of which affect mental health. The field of psychoneuroimmunology helps to explain all of this in more detail, and it’s really interesting to see the many connections between the nervous system, endocrine system, immune system, and overall mental health. (See references 9 and 10 in particular if you’re interested in learning more).

Disease, Mortality, and Longevity

So, you’ve started to get an idea of why carbohydrates are necessary, but I really want to bring this point home by tying it all together. How would I do this? Well, in this section I’ll simply show you that higher intake of carbohydrates leads to a longer and healthier life; it’s that simple.

Again, though, the key is carbohydrate quality. You can’t just consume a bunch of processed sugar in the name of increasing carbs to be healthy. On the other hand, consuming whole grains, starchy root vegetables, fruits, and so on, is associated with decreased cardiometabolic risk factors. Specifically, consuming these foods is related to lower blood pressure, increased HDL cholesterol, decreased LDL cholesterol, decreased inflammation, and improved insulin sensitivity (13). Yes, that’s right, complex carbohydrates IMPROVE insulin!) (13).

Oh, by the way, one oft-cited reason for going low-carb is to lose weight and improve cardiometabolic health, yet such a diet is not conclusively superior to any other diet for doing that (14).

High-quality carbohydrate consumption is also related to a decreased risk of coronary heart disease, stroke, diabetes, obesity, GI diseases, and certain cancers (15). The take-home message is that whole grains, fruits, starchy vegetables, and other natural carbohydrates aren’t bad; they’re one of, if not THEE, healthiest foods one can consume.

Live Longer and Healthier!

This is most likely why a high-carbohydrate diet is also associated with a longer lifespan (16). In a massive study conducted on human mortality and macronutrient intake, a diet consisting of 50 to 55 percent carbohydrates was shown to be associated with the longest lifespans (17). For reference, in a 2,000 calorie diet, this would amount to 1000 to 1,100 calories from carbohydrates, which would be 250 to 275 grams (4 calories per gram).

Furthermore, individuals who live in the “Blue Zones” (areas where people consistently live to 90 years old or more), their diets are characterized primarily by whole grains, legumes, fruits, and vegetables, with upwards of 60 percent carbohydrates or more! It is important to note, though, that both very low and very high carbohydrates were associated with the shortest lifespans. The latter might not be true if one consumes all healthy foods, but it nonetheless points to the importance of moderation.

So, overall, whole-food carbohydrates appear to reduce the risk of many chronic diseases plaguing individuals in modern society, and can thus help people live longer, and more importantly, healthier lives.

Conclusion: Eat More (High-Quality) Carbs!

A small percentage of people do well on a low-carbohydrate or ketogenic diet, but the vast majority of the population does well on a moderate to high carbohydrate diet, consisting of an abundance of whole, unprocessed plant foods. As you’ve seen, consuming fruits, starchy vegetables, whole grains, legumes, and other healthy carbohydrates offers a massive number of health benefits. (These benefits will likely be compounded when you consume enough healthy fats and protein as well, of course.)

So, whether you want to reduce stress, have more energy, improve your hormone levels, restore GI function, reduce the risk of chronic disease, or improve your health in really any manner, whole-food carbohydrates will most likely play a positive role in that quest. Your diet doesn’t have to be restrictive to be healthy. Whole-food carbohydrates are some of the most satisfying and delicious foods one can eat, so you’ll get the best of both worlds by eating meals you enjoy and improving your health simultaneously.

References

1. Barber, T. M., Kabisch, S., Pfeiffer, A., & Weickert, M. O. (2020). The Health Benefits of Dietary Fibre. Nutrients, 12(10), 3209. https://doi.org/10.3390/nu12103209

2. Cheng, X., Zheng, J., Lin, A., Xia, H., Zhang, Z., Gao, Q., … & Liu, H. (2020). A review: Roles of carbohydrates in human diseases through regulation of imbalanced intestinal microbiota. Journal of Functional Foods, 74, 104197. https://doi.org/10.1016/j.jff.2020.104197

3. Stachowicz, M., Lebiedzińska, A. The effect of diet components on the level of cortisol. Eur Food Res Technol 242, 2001–2009 (2016). https://doi.org/10.1007/s00217-016-2772-3

4. Guilliams, T. G., & Edwards, L. (2010). Chronic stress and the HPA axis. The standard, 9(2), 1-12. https://www.pointinstitute.org/wp-content/uploads/2012/10/standard_v_9.2_hpa_axis.pdf

5. Soltani, H., Keim, N. L., & Laugero, K. D. (2019). Increasing Dietary Carbohydrate as Part of a Healthy Whole Food Diet Intervention Dampens Eight Week Changes in Salivary Cortisol and Cortisol Responsiveness. Nutrients, 11(11), 2563. https://doi.org/10.3390/nu11112563

6. Kanter M. (2018). High-Quality Carbohydrates and Physical Performance: Expert Panel Report. Nutrition today, 53(1), 35–39. https://doi.org/10.1097/NT.0000000000000238

7. Cermak, N.M., van Loon, L.J.C. The Use of Carbohydrates During Exercise as an Ergogenic Aid. Sports Med 43, 1139–1155 (2013). https://doi.org/10.1007/s40279-013-0079-0

8. Cholewa, J. M., Newmire, D. E., & Zanchi, N. E. (2019). Carbohydrate restriction: Friend or foe of resistance-based exercise performance?. Nutrition, 60, 136-146. https://doi.org/10.1016/j.nut.2018.09.026

9. Firth, J., Gangwisch, J. E., Borisini, A., Wootton, R. E., & Mayer, E. A. (2020). Food and mood: how do diet and nutrition affect mental wellbeing?. bmj, 369. doi: 10.1136/bmj.m2440

10. Kiecolt-Glaser J. K. (2010). Stress, food, and inflammation: psychoneuroimmunology and nutrition at the cutting edge. Psychosomatic medicine, 72(4), 365–369. https://doi.org/10.1097/PSY.0b013e3181dbf489

11. Firth, J., Marx, W., Dash, S., Carney, R., Teasdale, S. B., Solmi, M., Stubbs, B., Schuch, F. B., Carvalho, A. F., Jacka, F., & Sarris, J. (2019). The Effects of Dietary Improvement on Symptoms of Depression and Anxiety: A Meta-Analysis of Randomized Controlled Trials. Psychosomatic medicine, 81(3), 265–280. https://doi.org/10.1097/PSY.0000000000000673

12. Rao, T. S., Asha, M. R., Ramesh, B. N., & Rao, K. S. (2008). Understanding nutrition, depression and mental illnesses. Indian journal of psychiatry, 50(2), 77–82. https://doi.org/10.4103/0019-5545.42391

13. Ludwig, D. S., Hu, F. B., Tappy, L., & Brand-Miller, J. (2018). Dietary carbohydrates: role of quality and quantity in chronic disease. BMJ (Clinical research ed.), 361, k2340. https://doi.org/10.1136/bmj.k2340

14. Kirkpatrick, C. F., Bolick, J. P., Kris-Etherton, P. M., Sikand, G., Aspry, K. E., Soffer, D. E., … & Maki, K. C. (2019). Review of current evidence and clinical recommendations on the effects of low-carbohydrate and very-low-carbohydrate (including ketogenic) diets for the management of body weight and other cardiometabolic risk factors: a scientific statement from the National Lipid Association Nutrition and Lifestyle Task Force. Journal of clinical lipidology, 13(5), 689-711.

15. Reynolds, A., Mann, J., Cummings, J., Winter, N., Mete, E., & Te Morenga, L. (2019). Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet, 393(10170), 434-445. https://doi.org/10.1016/S0140-6736(18)31809-9

16. Le Couteur, D.G., Solon-Biet, S., Cogger, V.C. et al. The impact of low-protein high-carbohydrate diets on aging and lifespan. Cell. Mol. Life Sci. 73, 1237–1252 (2016). https://doi.org/10.1007/s00018-015-2120-y

17. Seidelmann, S. B., Claggett, B., Cheng, S., Henglin, M., Shah, A., Steffen, L. M., … & Solomon, S. D. (2018). Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. The Lancet Public Health, 3(9), e419-e428. http://dx.doi.org/10.1016/ S2468-2667(18)30135-X