After proteins and fats, the third macro-nutrient follows some of the same patterns. But unlike the former two, at the time I am writing these lines, science still needs to better understand how carbohydrates impact our health and well-being. So let’s look at what researchers can observe and conclude, and why there is still confusion in some aspects.
As far as carbohydrates following similar patterns as fats and proteins, there is no such a thing as all carbs being the same. They are a family of molecules whose properties look the same in some aspects – they all reduce to glucose or fructose throughout the digestive process and look very different in other aspects. Candies and pasta are both carbs, but you can imagine that eating the same calorie count of one won’t impact your health in the way the other would.
Categorizing carbs by their molecular profile
Vitamins, minerals, and proteins are important, but we also need energy in the form of calories. Even a low caloric diet still has to supply them from some source. We discussed the topic of proteins: it’s best to limit their intake to only what we need. We discussed fats: there are the good and the not-so-good ones. Unsaturated fats like olive oil provide a wonderful supply of calories, for example. Then, carbs supply the rest, which is often the majority of the caloric total.
These molecules could be compared, to an extent, to Lego blocks. One is the glucose block, and the other block is the fructose. Here are the types as we know them today:
- Monosaccharides are the basic units, the single molecule of 1 glucose or 1 fructose.
- Disaccharides include sucrose, lactose, maltose, and are formed of two molecules.
- Oligosaccharides are composed of three to ten sugar units.
- Polysaccharides are aggregates of more than ten units. These include starches, energy storage found in plants, and glycogen, energy storage found in animals.
- Sugar alcohols. Sorbitol is the alcohol form of glucose, while mannitol is the alcohol form of fructose.
As the foods go through the digestive process, they are progressively broken down. The Lego constructs turn back into pieces. All carbs revert to glucose or fructose and enter the bloodstream. One of the over-simplifications from this fact is that no matter the type of carb they are digested as sugar, and they all have more or less the same effect on our metabolism.
Categorizing carbs by speed of absorption
When sugar is digested, the pancreas gets to work and releases insulin. This creates a spike in insulin and a spike in sugar levels, which get fed to cells and organs. When the process ends, insulin and sugar levels drop. These highs and lows are part of normal digesting, but when the spikes and dips are too intense, we get sick. Type-2 diabetes is rampant in developed countries, and it’s believed that the excessive and repeated ups and downs create the condition. In this type of diabetes, cells should react to insulin and complete the sugar absorption process, but instead, they under-react, which prompts the pancreas to release even more insulin, which in turn elevates blood sugar even more.
According to the Bradley, Craig Willcox and Makoto Suzuki in The Okinawa Program, carbohydrates can be very safe. Their non-harmfulness depends in large part on how slowly they can be absorbed. The speed of how quickly the sugar content of a given food is absorbed is measured by the glycemic index (GI). This metric is central. By using GI to measure carbs, we’re no longer looking at the molecules statically, but dynamically over a time interval. In other words, do carbs provide a steady stream of clean, usable and storable energy, or do they produce electroshock? They authors advocate that one reason for the Okinawan population to live long, is their consumption of complex carbohydrates, adding up to approximately 50% of total calories.
Complex carbohydrates tend to be less refined, include more fiber, which helps slow the absorption of sugars the food contains. Think whole grains instead of processed grains, juice that includes the pulp, brown rice over white rice, and so on. It was thought for a while that dietary fiber had no utility, but even if fiber does not provide nutrients, its utility is to slow down absorption and create this steady supply of energy to the body, limiting electrocution-type sugar spikes.
Glycogen as an energy buffer
When we digest carbohydrates, the broken-down sugar can either be used for immediate consumption and energy production, or for storage. When stored, the body converts these sugars into glycogen, which is mostly found in muscles. When engaging in a physical activity, glycogen is the fuel of choice for the body. It is readily accessible and depletes until we gradually transition to fat burning. What this means is that when there is some depletion, unused sugars have a place to go. People who never exercise tend to keep glycogen storage at high levels, so if they eat just a little more than they should, the extra energy doesn’t have place to go on the glycogen storage shelf, because it’s full. So, it stays in the blood stream, or gets eventually converted into body fat, which means weight gain. But for those who do exercise, these glycogen storage shelves provide a buffer for extra food intake to go without having to turn into body fat. It’s one of the many reasons why exercise, in this case endurance exercise, makes so much sense.
We don’t know what we don’t know
A fruit is alive. White flour is not alive. We don’t know if there is an influence on the way our body processes foods based on this dichotomy. There is no scientific evidence or even accumulated research that I know of, that looks at the health effect of eating foods that are fresh versus processed. The processing may remove micro-nutrients, fiber, or other elements that are not being measured today. When in doubt, observing the diet and lifestyle of long-lived populations provides a simple heuristic. Italians have eaten pasta, a complex carbohydrate, for generations, and when not abusing anything, have one of the highest life expectancy as a population. The same applies to Okinawans, eating whole ingredients that are minimally processed.
 Page 265, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, National Academy of Science, ISBN 978-0-309-08537-3 | DOI 10.17226/10490, https://www.nap.edu/catalog/10490/dietary-reference-intakes-for-energy-carbohydrate-fiber-fat-fatty-acids-cholesterol-protein-and-amino-acids
 Page 92, 93, The Okinawa Program
 Jensen J, Rustad PI, Kolnes AJ, Lai Y-C. The Role of Skeletal Muscle Glycogen Breakdown for Regulation of Insulin Sensitivity by Exercise. Frontiers in Physiology. 2011;2:112. doi:10.3389/fphys.2011.00112. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3248697/