The idea that eating carbohydrates makes you gain weight became popular when the Atkins Diet made a comeback in the early 2000s. Since then, the low-carb diet has stuck around, with studies proving that it can be effective for weight loss.
On the other side of the debate is the existence of traditional societies that ate diets high in carbohydrates without gaining weight or becoming insulin resistant. A closer look shows that carbohydrates have a profound influence on the human microbiome. Carbohydrates are not the problem, but what we do to them makes them unhealthy. Here’s a bit more background about carbs, and how to consume them the right way:
1. They didn’t always make us fat.
Carbohydrates are made up of glucose molecules, which serve as the human body’s ideal fuel. When we break them down during digestion, they cause blood sugar to increase, sending a signal to the pancreas to release insulin and telling the body to store fat.
A case study supposedly refuting this idea is the Kitavan people of the Melanesian Islands. Their traditional diet consisted of 60-70 percent of energy intake from carbohydrates with little to no presence of obesity, diabetes, or heart disease. Similar cases can be found in South American cultures such as the Aché hunter-gatherers of Paraguay and the Shuar people of the Amazon. Since many of their carbohydrates came from staple foods like root vegetables and fruit, they didn’t trigger the same insulin response that we typically see today.
2. Carbs are different today.
The main difference between ancestral carbohydrate intake and our diet today is that our ancestors' dietary sources were nearly solely delivered encased in cellular carbohydrates in the form of fibrous cellulose, which passed through the system untouched. Modern food processing strips away this fibrous coating in foods like rice, grains, and, of course, sugar. Even though we can’t digest dietary fiber found in fruits and vegetables, it is essential for health with both soluble and insoluble fiber regulating the digestion process and promoting bowel movement.
3. We need to consume carbs to be healthy.
Trillions of bacteria, referred to as the microbiome that live in our mouth, gut, and intestines also feed on carbohydrates and depend on us ingesting them for their own metabolic processes. This microbial population is designed to break down carbohydrates from natural, whole foods. A vegetable, for example, requires slower digesting microbes to move in, break down the cellulose casing, and release the simple sugars to feed other bacteria.
Studies have shown that our hunter-gatherer ancestors had more diverse bacteria in their mouth than we do today. This can be pinpointed to the time of the Industrial Revolution, or when we introduced wide-scale, acellular carbohydrates like refined flour and sugars into our diets.
4. Modern carbohydrates can lead to weight gain.
A diet too high in simple carbohydrates like bread and pasta will shift the microbial populations to favor the bacteria that feed on these smaller molecules. In the mouth when we eat too much sugar, a bug called Streptococcus mutans overgrows, releasing acid and resulting in tooth decay.
In your stomach, shifts in the microbiota have been shown to cause leptin imbalance as well as low-level inflammation, both markers of weight gain. Add this to insulin release and you’ve got the perfect environment for obesity and the true reason as to how modern carbohydrates trigger weight gain.
5. Processed foods are the real danger.
Much of the negative image around carbohydrates is due to the fact that we have consumed the modern processed version of them for so long. Simple, acellular carbohydrates like flour and sugar change our microbiome, which forms the likely connection between insulin-driven metabolic disease and weight gain.
Carbohydrates won’t make you gain weight as long as you stick to whole natural varieties that are found in our environment such as vegetables, fruits, and whole grains.
Dr. Steven Lin is a dentist, health writer, and TEDx speaker. He is currently writing his publication The Dental Diet, a journey of ancestral, genetic, and nutritional health based on the pioneering work of Dr. Weston A. Price and his discoveries of teeth as a cardinal sign of modern disease.