How many carbohydrates should I eat?
It seems that carbohydrates are now being demonized by many, and today I don't want to write an article telling you what you should do, but rather explain some important concepts of basic physiology so that you can draw your own conclusions.
When we eat food, we get “energy” from three main macronutrients: proteins, carbohydrates, and fats.
Ideally, we are interested in using fat (also called lipids) and carbohydrates (also called glucides) as an energy source, since proteins are the last resort and we are interested in proteins serving for tissue regeneration, production of enzymes and other important molecules and not as an energy source.
Let's understand what carbohydrates are
Carbohydrates are sugar molecules: when we eat bread, pasta, or fruit, our body breaks these carbohydrates down into glucose molecules during the digestive process so we can absorb and use them.
This glucose, or blood sugar, is the main source of energy for the body's cells, tissues, and organs. When it reaches the bloodstream after being absorbed through the small intestine, our pancreas secretes insulin, which causes cells to express (place on their membranes) a receptor called GLUT (there are several types), a kind of gate that allows us to absorb this sugar circulating in our blood. Once it enters the cell, through certain enzymatic processes, it is converted into pyruvate, then into acetyl-CoA, and finally enters our mitochondria, present in all the body's cells.
Here begins the citric acid cycle or Krebs cycle, where this Acetyl-CoA molecule will go through certain transformation processes producing ATP, NADH and FADH as final products, and our cells will now have sufficient energy.
And what about fats?
Well, when they are absorbed, largely thanks to the bile emulsion produced by the liver and pancreatic enzymes, they are absorbed in the small intestine, transported by chylomicrons, and broken down into fatty acids and glycerol. Short-chain fatty acids can easily enter the mitochondria; long-chain fatty acids must be introduced by Acyl-CoA, whose action requires the presence of Carnitine. Once inside the mitochondria, the fatty acids will be fragmented and shortened, producing acetyls suitable for use in the Krebs cycle. The process is called fatty acid beta-oxidation.
That is, from the two substrates our body can produce ATP, the energy molecule with which our cells can function.
And here comes the problem… Can we absorb all the carbohydrates and fats we eat? What happens if we're constantly giving food?
Well, logically, our bodies are intelligent. We're capable of storing excess glucose in the liver (100–120 grams) and in the muscles (15–25 grams per kg of muscle mass), which we call glycogen. When these stores are full, this excess blood glucose is stored as fat, which we call adipose tissue, just like when we consume excess fat. Think about it... if our cells absorbed all the carbohydrates or fats we eat without limit, we would die!
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What happens if we have high blood glucose levels?
The current problem is that we have greatly reduced energy expenditure, a society with a conspicuous lack of muscle mass, and a high carbohydrate consumption, energy we don't need and can't manage. When we have high blood sugar levels, this causes us to become highly dependent on carbohydrates, we are unable to fast, we are in an inflammatory state, we struggle to lose weight, we suffer from dry mouth, blurred vision, or recurrent infections, among other things.
Think about how when you eat carbohydrates, your pancreas has to secrete insulin so your cells can absorb that glucose. But there comes a point where, if you consume too many carbohydrates and don't expend enough energy, your cells become resistant to insulin, "closing the floodgates," and unable to absorb that glucose to protect us. In the long term, your pancreas will try to secrete more insulin until it becomes exhausted and no longer produces enough insulin, resulting in type 2 diabetes.
On the other hand, we must remember that a high-fat diet rich in palmitic acid, a SFA, is associated with decreased insulin sensitivity and can also increase atherosclerosis parameters. Not only carbohydrates are harmful to us, but other types of fat can contribute to this insulin resistance and type 2 diabetes.
With this information, how much carbohydrate do I need?
When we read this information, we get scared and think we'll end up diabetic. However, if you're an active, active person who maintains a healthy lifestyle, this won't be the case for you. Your muscle mass will tolerate more glucose and manage it much better than someone who's obese and sedentary because you're expending energy, and your cells are receptive; they need energy. So, how many grams of carbohydrates do I need? Let me put you in four situations:
- Obese people who don't exercise: We recommend a low carbohydrate intake (25 to 50g per day), a moderate to high protein intake (1.2 to 1.4g per kg of body weight), and a high intake of healthy fats. We should avoid carbohydrates at night because insulin synthesis is lower.
- Obese people who train in CrossFit/endurance/weight training: We recommend consuming 50-125g of carbohydrates, a moderate-to-high intake of protein (1, 2, 1, 6g per kg of body weight), and a moderate intake of healthy fats. If you have prediabetes metabolic problems, we recommend consuming 25-50g daily. We recommend avoiding carbohydrates at night because insulin synthesis is lower.
- People with a healthy weight but who don't exercise: We recommend a low-carb intake of 25-50g of carbohydrates daily, a moderate/high-protein diet (1.2/1.4g per kg of body weight), and moderate fat intake.
- People with a correct weight and who train CrossFit/endurance/weight training: a consumption of 150/250g of carbohydrates per day (in the case of weight training 50-125g per day), a high protein consumption (1.6/2g per kg of weight) and a moderate consumption of fats.
The secret is to consume the right amount based on your caloric expenditure and muscle mass. You don't have to be afraid of carbohydrates, but rather consume the right amount for you. I should note that some people feel more comfortable on a low-carb diet, and we can exercise and gain muscle mass on a low-carb diet if we consume more than we expend. However, it's not optimal for gaining muscle mass, and personally, I don't see a permanent ketogenic diet as optimal at all for athletes.
I'll give you some tips:
- You can calculate the amount of carbohydrates with applications like My Fitnesspal, not so that you always weigh everything you eat, but so that you get an idea of the amount you need depending on the exercise you do.
- On rest days, take advantage of the opportunity to reduce carbohydrates and consume more fat, and on more demanding days, the opposite.
- Perform strength training at least 3 days a week combined with cardiovascular exercise such as walking, HIT, dancing, running 2 or 3 days a week, this will help us stay metabolically healthy.
I hope this has helped you and please feel free to share it with anyone who needs this information.