One of the quotes most pertinent to my work as a dietitian actually comes from a religion professor, Alan Levinovitz, who has taken to writing about nutrition in recent years because of the intersectionality of spirituality and food. He explains, “It’s terrifying to live in a place where the causes of diseases like Alzheimer’s, autism, or ADHD, or the causes of weight gain, are mysterious. So what we do is come up with certain causes for the things that we fear. If we’re trying to avoid things that we fear, why would we invent a world full of toxins that don’t really exist? Again, it’s about control. After all, if there are things that we’re scared of, then at least we know what to avoid. If there is a sacred diet, and if there are foods that are really taboo, yeah, it’s scary, but it’s also empowering, because we can readily identify culinary good and evil, and then we have a path that we can follow that’s salvific.”
In other words, good/bad food dichotomies offer comfort even if they are based more on theology than science, but why are carbohydrates often demonized? After all, given that the dietary reference intakes call for 45% to 65% of our total energy intake to come from carbohydrates, these macronutrients cannot really be that evil, can they?
First, remember the crosshairs of nutrition scapegoating are fickle and used to point elsewhere, such as fat in the 1980s and gluten more recently. These days, the most common reason I hear why people look down on carbohydrates as opposed to other foods is the perceived association between carbohydrate intake and weight change. Someone cuts his carbs, sees himself quickly drop weight, and therefore believes that carbohydrate elimination or reduction is the key to weight loss. Similarly, the weight regain that occurs with reintroduction of carbohydrates reinforces the notion that carbs are problematic.
Such conclusions, which are understandable if based solely on observation and experience, do not take into account the physiology of what actually happens within the body. We store carbohydrates in the form of glycogen in our liver and muscles so we have fuel for various processes, including physical activity. On a chemical level, water is bound up with the glycogen. Therefore, when someone reduces his carbohydrate intake and quickly drops weight, what he is really losing is water weight, not fat mass, as his glycogen stores decrease. Similarly, when he reintroduces carbohydrates, he rebuilds his glycogen stores and the water that gets packaged with it, and he consequently regains weight.
Furthermore, carbohydrate reduction can trigger a downward spiral. Because our bodies are adept at telling us when we are in need of a nutrient (For example, putting aside extraneous circumstances, we feel thirsty when we are dehydrated, and the action of drinking becomes less pleasurable as we rehydrate.), when we cut our carbs, we in turn feel an increased drive to consume them. If and when we finally eat them again, we are likely to overconsume, partly due to the body making up for the deficit and partly as a natural reaction to restriction. This overconsumption, especially if weight regain accompanies it, reinforces the preconceived notion that carbohydrates are problematic. Sometimes people even go so far as to believe they have an “addiction” to carbohydrates or specifically sugar. Thus, they cut carbs again and the cycle continues. This is a form of paradigm blindness in that some people do not realize that their presumed solution actually exacerbates the problem, so they keep adding more of the supposed solution to the ever-worsening issue.
Even if someone does manage to sustain long-term carbohydrate reduction, such behavior comes with risks. For example, fiber, which is important for cardiovascular health, energy stability, and bowel function regularity, naturally occurs in high-carbohydrate foods, such as legumes, vegetables, and whole grains. Therefore, reducing or eliminating these foods makes achieving adequate fiber intake a challenge. Carbohydrates are the brain’s primary source of energy, so not taking in enough of them risks concentration lapses, mental fogginess, and malaise.
During physical activity, our bodies rely on carbohydrates as the primary fuel source. As an endurance athlete, I have experienced the fallout from inadequate carbohydrate intake firsthand. Only twice in my life have I failed to complete a long-distance bicycle ride that I began: the first was when I fell off my bike and fractured my spine, and the other was a few years later while I was experimenting with a low-carb diet. During the latter ride, I became so fatigued and dizzy that I could not continue and had to have someone drive me home.
If carbohydrate reduction is not the key to good nutrition, what is? Well, the answer is complicated and not easily distilled into a soundbite. Health is both complex and multifaceted, and no two individuals are likely to define it in exactly the same way. Therefore, how we approach it from the perspective of nutrition has to be individualized as well. Speaking generally though, we suggest doing away with good/bad food dichotomies, which are more harmful than helpful, and instead placing all foods on a level playing field of morality. Rather than letting issues of guilt and virtue steer your eating, let your body’s internal cues be your compass. When you do that, you just may find that your carbohydrate intake falls within the aforementioned dietary reference intake range. Lord have mercy.