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To Carb or Not To Carb -- or, To Ketone? (Part II)

Updated: Mar 31, 2022

Recent studies in nutrition and dietary science have drawn a connection between carbs and an increase in inflammation. These new studies, combined with our understanding of type II diabetes and the relationship between carbs and insulin (i.e, high intake of certain carbs leads to and exacerbates type II diabetes), have led many to conclude the following: Carbohydrates are bad for you and should not be consumed.

This conclusion is a drastic oversimplification. Yes, some carbs are bad. Some carbs will spike insulin and cause inflammation in the body. At the same time, some carbs are good and carry important nutrients and minerals our bodies need.

Just as there are good and bad fats (olive oil vs partially hydrogenated oil in oreos), there are good and bad carbs -- and carbs that exist somewhere in between. The "bad" carbs are carbs that cause abnormally high insulin spikes and cause high levels of inflammation. The signature "bad carb" is high fructose corn syrup, which should be avoided entirely. "Good" carbs are the carbs in more natural sources: fruits, whole grains, brown rice, legumes, oats, and starchy vegetables. These carbs do not spike insulin levels in the way high fructose corn syrup does, and virtually no evidence exists drawing a connection between these foods and an increase in inflammation. In fact, with regards to fruits, the opposite is the case.

Refined pasta, bread, and white rice are the "in-between zone." These foods may spike insulin and may increase inflammation, but not as drastically as high fructose corn syrup. They also do not carry the nutrients and minerals that whole grains carry. At the same time, if you are an endurance athlete or an athlete who loves HIIT sessions, your body probably needs the calories and fast-acting carbs from these refined carbohydrate groups. In sum, while these carbs aren't necessarily "bad," the better option for people who are seeking to lose weight and/or gain health is whole grains.

This brings us to the topic of the ketone diet. While it is not a no-carb diet, the ketone diet is still drastically low in carbohydrate intake. Here are 5 things to keep in mind before embarking on the ketone path:

  1. For all its hype, the ketone diet has not withstood the test of time. Some studies have shown that a high-fat diet can place stress on the kidneys and liver. Additionally, many dietitians are concerned about the effects of the ketone diet on heart health and high blood pressure (again, connected to the increase in fats over carbs). If a person consumes a ketone diet for 20-30 years, we do not yet know how it will affect their longevity or well-being over that period of time.

  2. The ketone diet allows for 5-10% of calories to be from carbohydrates. This is a very low, possibly dangerously low, number. The Dietary Guidelines for Americans recommend that carbohydrates make up 45% to 65% of total daily calories. In other words, if you get 2,000 calories a day, between 900 and 1,300 calories should be from carbohydrates; the ketone diet would allow for 100-200 calories a day. Carbohydrates carry important nutrients and vitamins (especially the B vitamins). Following a diet this low in carbohydrates could run the risk of becoming deficient in one of these essential vitamins.

  3. When it comes to fat loss, the tried and proven technique (a technique that has withstood the test of time) is simple: calories in, calories out. If you are embracing the ketone diet with a goal of weight-loss, be sure to count your caloric intake. Carbs and protein have 4 calories/gram while fat has 9 calories/gram. If one is not careful, those calories can add up very quickly.

  4. Relatedly, without the macronutrient carbohydrate, it's easy to overconsume foods high in fats, and particularly saturated fats. Overconsumption of foods high in saturated fats (red meats, full-fat dairy) is considered a major contributing factor to heart disease, clogged arteries, and high blood pressure. In moderation, saturated fats are not necessarily "bad," but a high consumption of saturated fats increases the LDL ("bad") cholesterol, while foods containing healthy fats (olive oil, nuts) increase the HDL ("good") cholesterol. A high LDL may be balanced out by a high HDL, but in general, those who follow a ketone diet may tend to consume an unhealthy percentage of fats.

  5. Consider exercise. The type of exercise and the duration of exercise both affect how our bodies process foods for energy. HIIT sequences and any form of exercise where you push yourself to your cardiovascular limits (heart pumping, gasping for breath, legs heavy, taste of lactic acid in your mouth) requires your body to move into what's called the "anaerobic zone." This is the metabolic zone that relies almost entirely on carbs for performance. In this zone, your muscles are calling for energy fast and carbs are the fast-acting energy source. Our muscles cannot break down fats near as quickly. If your body does not have enough carbs to fulfill the demands for exercise, you "bonk" or "hit the wall." Bonking is not a good place to be, especially if you're in any kind of endurance event. It is characterized as an overwhelming or sudden loss of energy. Because the muscles do not have access to carbs, they must slow down to a pace where they are burning entirely fats (eg, walking or biking at a very slow pace).

Finding the diet that's right for you entails paying attention to how foods make you feel. If the ketone diet is making you feel awful, then you have to ask yourself, "Is it really worth it?" Foods should give us energy, but everyone's bodies are different. The way our bodies metabolize food and the way foods affect us are unique and individualized. There is no one universal diet (except possibly the Mediterranean diet) and the way our bodies metabolize foods is contingent upon a myriad of factors (exercise, exercise duration, type of exercise, genetics, hormones, muscle-type, etc.). It's important for each of us to figure out which foods work well for our unique lifestyles and fitness goals. I suggest keeping a food journal (check out and in addition to counting calories, also make note of how foods and combinations of foods make you feel.

In order to find the right nutrition plan for you, you have to know yourself; dieting is like philosophy -- it's a search for identity. Hamlet knew the answer to his own question, "To be or not to be?" So, too, do we know the answer to the question, "To carb or not to carb?" After all, you are what you eat!

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