Nutrition myths and fad diets really irritate me. All of them. But I must admit there’s one that’s lately driving me mad with a special intensity: the demonization of carbohydrates.
Look, I get it: the massive consumption of ultra-processed fast food is making people fat and unhealthy. And those are mainly carbohydrate-rich foods. Or rather, high-sugar foods (not all carbs are equal). Oh, and they also happen to be usually high in added fats, including trans fats.
Hopefully, by now you’re already seeing that “carbohydrates” as a macronutrient aren’t the real problem. Words like massive, ultra-processed, sugar and trans fats should point you in the right direction to understand the issue.
But if you’re still suspicious of carbs… keep reading.
I know what you might say: “but we don’t need carbs”. It’s true. We don’t need carbs. BUT. We should eat them. Or, to say it in an elegant and easy to remember way: we don’t need them to survive, but we need them to live.
Let me explain this further. While we have no physiological requirements for dietary carbohydrates, they have so many benefits that make a positive impact on our health that it would be silly not to eat them (especially taking into account how great they taste!). Anywhere from 1 up to 10 grams of carbohydrates per kg of body weight will do you good.
To start with, your brain and central nervous system use glucose as their primary fuel, and require a continued supply of it. Carbs are our body’s preferred source for glucose. We can obtain glucose through another process called gluconeogenesis, by which other nutritional compounds are turned into glucose, but it’s not as effective as just eating the *darn* carbs. So it’s a good adaptive mechanism for periods where there aren’t carbs available, but it’s not meant to be used just to satisfy your whim of being a cool low carb idol.
Don’t worry, I won’t take the route of bashing this position (well, I might throw some remarks… #sorrynotsorry). Instead, I will now highlight the amazing benefits of including a good amount of carbs in your diet!
Note: this only applies to a diet whose main sources of carbohydrates are whole grains, legumes, vegetables and fruits. Refined grains are fine but shouldn’t be a staple. And the ultra-processed foods I described earlier should be exceptional.
This is a special component found in certain types of carbohydrates, such as legumes, oats, green bananas or rice. Its peculiarity consists on the fact that it’s not digested in the small intestine, but passes to the large bowel, where it’s fermented by the microbiota. It acts as a prebiotic, that is, it stimulates the growth and activity of the gut bacteria. As a byproduct of the fermentation process, short-chain fatty acids are generated. The combination of these two events has a myriad of positive effects:
- Increases mineral absorption and bone mineralization.
- Improves bowel habits, increasing stool frequency and decreasing fecal pH. This in turn decreases the risk of bowel diseases.
- Decreases cancer risk by favorably modulating the expression of genes related to biotransformation in carcinoma cells.
- Reduces the risk of type-2 diabetes because it improves glucose tolerance and decreases endogenous glucose production.
*Pro tip for type-2 diabetics or pre-diabetics: cook and cool your rice in order to increase its resistant starch content.
Fibre can be defined as the indigestible portion of food derived from plants (non-starch polysaccharides and other plant components such as cellulose). There are 2 types of fibre ; most plant foods contain a combination of both, but in different proportions, which is another reason to ensure you eat a varied diet.
- Soluble fibre slows transit time and helps lower cholesterol —the mechanism is linked to its interaction with bile acids— and stabilize blood glucose levels. It can be found in fruits, vegetables, oats, barley and legumes.
- Insoluble fibre softens the contents of our bowels and supports regular bowel movements. It can be found in whole grains, nuts, seeds and the skin of fruits and vegetables (don’t peel them when you don’t need to!).
The consequences of eating fibre
Thanks to the good effects of fibre on digestion and bowel transit, it has been shown over and over to reduce the risk of colorectal cancer.
Apart from the benefits mentioned, fibre is great for weight loss. First, because it helps you feel more satiated. But second, because it actually has less calories than normal carbohydrates. Indeed, we’ve all studied at school that carbohydrates have 4 kcals per gram, but it’s been proven that fibre only has 2 kcals per gram. Food labelling is starting to take notice of this, but not always, which means the energy content of foods rich in fibre is often overestimated (up to 32% in almonds, for example). So you can eat more for less!
For all these reasons, it’s recommended to eat about 25-30 grams of fibre daily. Sadly, in Spain (the country I live in) we only consume 15’8 grams.
It’s worth noting that these recommendations don’t apply to people with gut diseases such as Crohn’s or IBS, who should watch their intake of fibre and resistant starch according to what their doctors tell them.
Protein sparing effect
Low carb diets aren’t optimal for muscle gain either. Glycogen (the stored form of glucose in our muscles) has a protein sparing effect. When we exercise with low levels of glycogen, protein catabolism —that is, breakdown or degradation— increases. Most bodybuilder gurus insist on the importance of protein and strength training, and they’re right, but more and more express contempt towards carbohydrates, which is a mistake since that way they’re not optimizing their protein intake and training as much as they could.
Protein fulfills loads of key functions within the body: energetic, structural (tissues), transport (red blood cells), hormonal, enzymatic, immune (antibodies), keeping acid base balance and fluid balance.
But what about insulin
Most people nowadays tend to think that, when you eat carbs, your body releases insulin, and therefore you stop burning fat, and therefore you get fat. That’s a joke of an explanation of the much more complex (and positive) process that happens.
What really happens with insulin
When you consume carbs, there’s more glucose in your blood, and therefore the pancreas releases insulin to help that glucose get into the cells. Free fatty acids in the blood are also shuttled into cells in this process. Fat metabolism decreases, while carbohydrate metabolism increases. Once blood glucose levels are balanced again, the body goes back to burning fat. Over a 24-hour period, it will all balance out if you’re eating maintenance calories. You won’t gain weight because of insulin.
If all you ate was fat, you wouldn’t burn all of it, you would still store fat in a calorie surplus, since the hormone responsible for fat metabolism is suppressed when you eat too much fat regardless of insulin.
Not to mention that you can’t live on fat only, you need protein and guess what… protein also releases insulin, in fact sometimes more than carbohydrates. So people on low carb diets are definitely producing a lot of insulin too (yes, some people go to the extreme of going low protein because of that… so scary).
Insulin also increases leptin, which is a hormone that reduces your appetite. So it can actually be beneficial for weight loss.
I won’t talk more about insulin because James Krieger has done an amazing job writing a series of 6 excellent articles debunking all the myths around it and presenting some mind-blowing facts that will make you love insulin. Read all of them!
How many times in life we can only please either our brain or our heart… Those are difficult decisions. Fortunately, they agree on something: they like carbs. We’ve already discussed the benefits for the brain.
Overweight and obese people are at greater risk of developing cardiovascular diseases, and the best thing they can do to avoid them is to lose weight. However, given similar weight losses, consuming whole grains leads to a greater reduction of CRP, a biomarker of cardiovascular events, and of abdominal body fat (it’s not just total body fat that matters, its distribution is important as well; the abdominal region is the most dangerous area of fat storage). Note that this only happens with WHOLE grains!
In fact, in order to achieve optimal health and prevent cardiovascular disease, it is recommended to eat at least 48 grams of whole grains per day. A meta analysis that examines 45 prospective cohort studies and 21 randomized control trials on the effect of whole grains in diabetes, cardiovascular disease and weight gain supports this recommendation.
What’s more: it’s been shown that the dose-response inverse relation between whole grain intake and heart disease persists up to about 210-225 grams per day! (clic the link and you will see how it also applies to other illnesses).
As a survivor of anorexia nervosa, weight loss isn’t usually my focus. However, I know many people need to lose weight in order to be healthy, the same as I needed to gain weight. In fact, that would help massively to reduce the rates of illnesses we have mentioned: type-2 diabetes, cancer, cardiovascular diseases.
And, once the “insulin hypothesis” has been debunked, we have seen carbohydrates can and should be included in a healthy weight loss diet (remember the points about fibre and leptin). Especially if they help to improve adherence, which of course has to be evaluated on an individual basis.
But here is another important fact to consider: the body actually hates having to convert carbohydrates into fat (a process called de novo lipogenesis). It would much rather either store it as muscle glycogen or just burn it by increasing your NEAT, non-exercise activity thermogenesis, that is, how much you move during the day. This means, it pushes you to be more active.
The process itself is quite inefficient and wastes a lot of energy, so you end up burning part of the calories anyway just by having to convert carbs into fat… whereas if you eat fat in a surplus, you store it as fat directly.
Carbs is not the only thing carby foods provide. I don’t think we need to talk about legumes, vegetables and fruits here because their role in this instance is universally acknowledged. However, grains —again, whole grains— have micronutrients too!
We have already talked about fibre, but they are also filled with other micronutrients: vitamins (E —antioxidant and boosts immune system—; B —there are 8 of them, and they help a variety of enzymes do their work—) and minerals (iron —used to make hemoglobin and other tissues—; magnesium —used to regulate muscle and nerve functions, among other processes—; zinc —helps immune system, and is needed to make proteins and DNA—).
I hope now you know that carbohydrates aren’t bad. That, in fact, they are good. Very good indeed, provided that you choose the right sources (whole, unprocessed foods)… but hey, isn’t that the same with protein and fat?
The low carb and keto fads may come and go, but the scientific facts will remain. Remember, if anything, we’re consuming too few *quality* carbohydrates! (read the fibre section).
Follow a balanced diet, don’t demonize entire food groups, and fuel yourself with the energy you need to fully live all the awesome things God puts in your life everyday <3