Carbs consumption and its effect on obesity has been a very controversial topic for a long time.
Even today, there is a lot of contradictory information published in scientific journals and, what’s worse, public policies are still based on data that has been proven wrong.
This has led to a massive epidemic of obesity in western countries.
Everything began when the classic food pyramid was constructed based on a flawed study led by Ancel Keys that showed a correlation between fat consumption and coronary diseases…
Now, with perspective, we see that this study was poorly designed (it used only 7 countries to draw its conclusions) and extremely biased (if a different cohort of countries had been chosen, results would have been the opposite) and it was not until recently that the hypothesis has been refuted.
Carbs and obesity
In a recent counter-strike, nutritionists pointed to the high-carb diet as being the main cause of obesity because of its effects on insulin levels. Insulin is the hormone that controls carbohydrate assimilation in our body. However, insulin has one side effect: when there are a lot of carbs in our diet, insulin triggers glucose metabolism, and then the accumulation of fat in the adipocytes (fat cells). This hypothesis, discussed in the book Good Calories, Bad Calories by science author Gary Taubes, was truly a breakthrough, as it was the first to highlight the failures in addressing diets exclusively by the laws of thermodynamics (caloric intake vs. caloric burn), and that diets should also be guided by the laws of biology as well as these three statements:
- Insulin blocks the body’s ability to burn fat. The more insulin there is, the harder it is to burn fat.
- Insulin changes the body’s metabolism and its hunger responses.
- Carbohydrates, especially refined carbohydrates, are the suspected cause of elevated insulin and the leading cause of common obesity.
We know that excess carbohydrates cause chronically high insulin and that this hormone is associated with the occurrence of several disorders such as PCOS (Polycystic Ovary Syndrome), Type II Diabetes, and Metabolic Syndrome. In addition, excess energy can saturate cells, resulting in inflammation and this, in turn, causes insulin resistance (take a look at this article talking about inflammatory carbs).
So it seems that high carbs are the causes of all evil, doesn’t it? Maybe not.
If we take a step back and look at the big picture of what we eat and not just the macronutrients contained, we see that carbs are not harmful per se, and neither are they the cause of insulin resistance. The true evil in this game is eating too much:
- Insulin resistance appears to be primarily a deliberate way for our body’s cells to protect themselves. Faced with an excess of food, the cells respond, “stop sending so much energy. It’s too much!” And all the excess energy is stored as fat
- The accumulation of fat eventually leads to excessive growth in fatty tissue, which then releases pro-inflammatory substances.
- Inflammation is a cause of insulin resistance as Wilhelm Ebstein proved in his article on 1876, (Ebstein W. Zur therapie des diabetes mellitus insbesondere uber die anwendeng der salicylauren natron bei demselben. Berliner Klinische Wochenschrift 1876; 13:337-340).
It becomes quite clear that insulin is not the cause of obesity but the consequence.
Then why are high-carb diets associated with insulin resistance?
Because most of the carbs we eat are not as satiating as fat: a study comparing a high-carb diet with a high-fat diet of the same caloric and protein intake found that the high-carb diet would leave a person feeling more hungry than the high-fat diet. This does not happen with all carbs, but with the ones that stimulate our reward system.
Which carbs are healthy?
We need to choose those carbs that don’t activate our hedonistic hunger or cause us to over eat (read more here). And as always we need to avoid foods that cause inflammation, many of which are carbohydrates. The next 4 rules will keep you out of harm’s way:
- Avoid processed food. Processed foods are designed for maximum consumption. They bypass our natural hunger sensor and trick our bodies into thinking we need more by kicking our reward-system (read: addictive!) hunger into action.
- Avoid inflammatory foods. Gluten and anti-nutrient rich grains and legumes.
- Choose foods with high nutritional density. The food we eat must supply two things: energy and micronutrients. If a food is calorie-rich but low in micronutrients, we need to eat more to meet our vitamin and mineral needs. This brings excess calories and results in weight gain. Or, we eat less to restrict calories but fall short on nutrients. Vegetables, followed by fruits at a distant second, are foods with high nutritional density.
- Keep your own personal health conditions in mind. Digestive tract dysfunctions, chronic viral infections and the like can affect your carbohydrate tolerance.
And finally here is the list of good (and bad) carbs, simple as all true and meaningful things in life:
- First Vegetables, followed by fruits and tubers.
- Limit or restrict consumption of bread, pasta, flour
- Avoid empty calories found in sugar and sugar-rich products.