The Truth About Carbs
- Subtitle: lay the debate to rest.
- Excerpt: For decades now nutritionists and other vested parties have argued about carbs. One camp says they’re guilty of being uniquely fattening and metabolically damaging.
Here is a simplified and shortened synopsis of what’s really happening with carbs in our diet. You can visit our website at thrivehm.co.uk/the-truth-about-carbs, here we have a longer video explainer. For now, let me explain while being as concise as possible.
The main point I want you to take away from this article is that neither carbs or fats are uniquely fattening independently of calories. However, the combination of carbs and fats is more fattening than either one alone, and the combination of sugar and saturated fat is extremely fattening.
If you over eat carbohydrates, blood sugar rises. It has been proposed that excess carbs in the blood get stored in fat. This is true, but only to a limited extent. The body can take glucose molecules from the blood and convert them into triglycerides (the storage form of fat) inside fat cells, but this process is not efficient. If I overfed you by 1000kcal per day from pure carbs for three months you would gain about 300g fat from this process. What actually happens is that your blood sugar remains elevated for a long time, causing damage to your cells. If our bodies were as good at storing glucose as fat, there would be very few Type 2 diabetics. The way excess carbs lead to fat gain is via the fat you eat alongside the carbs.
When fats are eaten they go straight to the liver, which decides what to do with those fats. If blood sugar is low, the liver will decide that energy from fat is needed in the periphery, and kick out free fatty acids (FFAs) which is the energy source form of fat that cells can use. However if blood sugar is elevated, the liver will determine that no extra energy from fats is needed and kick out triglycerides (TG) instead (the storage form of fat). You can easily see this on blood tests looking at post meal lipids after very low carbohydrate meals vs higher carbohydrate meals with the same fat content. Carbs and fats together raise TG in a pronounced way.
Therefore, slightly overeating on a very low carbohydrate diet will lead to negligible fat gains. The body will utilise the extra fats for greater energy production and usage through myriad pathways. Overeating the same amount of calories on a high carbohydrate but very low fat diet will lead to similar effects on weight, because the body will use the calories from carbs for energy and not be efficient at storing them. But, overeat the same amount of calories on a high fat and high carbohydrate diet and fat gain will be greater. Most fat that makes it to the liver while blood sugar is elevated will be stored. This could theoretically lead to further overeating because once the fat has been stored and the blood sugar drops hunger will be triggered to eat again, rather than automatically tapping into the previously stored fats.
If the excess calories are being eaten from specifically sugar and saturated fats the situation gets worse. The fructose element of the sugar is taken directly to the liver, giving a falsely high view of carbohydrate availability to the liver. This strongly turns on the fat storage pathways. Combine this with high amounts of readily stored saturated fats and you have a recipe for rapid fat storage. Research has shown that this deadly combination will lead to preferential storage of fats in the viscera, (the fat wrapped around your internal organs). This type of fat is the most damaging to health and most strongly associated with cancer, diabetes, cardiovascular disease and other health concerns.
This is why we can observe very low levels of obesity in high carbohydrate low fat diets such as the Japanese, but also in very high fat low carb diets such as the Inuit. Yet we see very high levels of obesity and disease resulting from western diets. Western diets are high in junk (sugar and saturated fat). Take cookies, doughnuts, pizza, chips, and ice cream for examples, all high in BOTH saturated fats AND simple sugars.
The truth about carbs is the same as the truth about fats. Neither one is uniquely and inherently fattening or deleterious to health, But the combination of them together, in excess, is. Bottom line, stay away from junk, not all calories are treated equally by the body.