Carbohydrates Timing

Carbohydrates Timing – When Should I Eat Them?

Carbohydrates are needed if we want to optimize sports performance and body composition. However, chrononutrition here plays a big role, modulating insulin secretion and glucose metabolism. So the question is, when should we eat carbohydrates? All about carbohydrates timing explained in this article!

In this post we'll go through a brief introduction of what carbohydrates are and how it can help us optimizing performance and muscle metabolism. Then, we'll talk about the best moments to take carbohydrates and the science behind.

Stay tuned and enjoy the post!

Carbohydrates, or saccarides, are organic biomolecules formed by carbon (C), hydrogen (H), and oxygen (O). Following the formula Cx(H2O)y, they can be found in two different structures; linear and cyclic (source).

The simplest form of carbohydrates are called monosaccharides, formed by a single saccharide. From these, we can then build all carbohydrates known to date. These will be called polysaccharides (study)

Carbohydrates Structure

Carbohydrates, together with proteins and fats, make up 99% of our metabolism (study), with the other 1% referring to vitamins and minerals.

Each maconutrient plays a different role in our organism, creating an interplay between them to optimize metabolic work and make it more efficient. While proteins and fats are essential (we can't make the on our own), carbohydrates are not. This is, if we didn't include them in our diet, we would survive. This is the principle of the ketogenic diet (study)

Based on the fact carbohydrates are non-essential, people is starting to remove them from their diets, without knowing how much they can actually help you (specially if you practice some kind of sport).

If you want to know why carbohdrates are good for you... click on the button below!

Types of Carbohydrates

There are many ways to classify carbohydrates. In this case, we'll classify them based on the complexity of their structure.

Here we can have two main types of carbohydrates: simple and complex. While the former is composed by less than three monosaccharides joined together, complex carbohydrates are larger molecules formed by more than three monosaccharides. 

carbohydrates classification

Why Are Carbohydrates Important?

Carbohydrates, although being non-essential, play an important role in our metabolism. We could live without carbohydrates on our diet, but our body needs to replace them with other molecules; ketone bodies (study)

Energy Metabolism

Carbohydrates are the main source of energy of human diet (study). When there are carbohydrates available, our metabolism will convert them into glucose or fructose, to enter what's called the Central Metabolism (study).

carbohydrates metabolism

The central glucose metabolism is composed by three main coupled pathways:

  1. Glycolisis: Oxidation of glucose into pyruvate in the cytosol (study)
  2. Citric Acid Cycle: Conversion of pyruvate into Acetyl-CoA and yield of reduced cofactors and direct energy. Happens in the mitochondria (study)
  3. Oxidative Phosporylation: Electron transport chain to produce 30-32 ATP in the inner membrane of the mitochondria (study)

While the first two steps don't require oxygen, oxidative phosphorylation does require oxygen to accept the last electron in the transport chain and form water. Therefore, glucose metabolism will be the primary energy pathway when doing aerobic exercise (study).

If you are more into strength training and anaerobic disciplines, carbohydrates can also help you. We can store glucose as glycogen, which can be used for energy production when glucose is absent (study). Glucose can also be oxidized through anaerobic fermentation, yielding lactic acid (study)

So, to conclude, we can benefit from carbohydrates both during aerobic and anaerobic exercise. Carbohydrates intake prior to exercise will help delaying fatigue and improving performance (study)

Insulin Response

Carbohydrates induce insulin production and release. When blood glucose is available, insulin transports glucose to the cell and lets it enter by the receptor GLUT-4 (study).

Insulin and carbohydrates

Because insulin increases glucose usage, it has been highly related to energy metabolism (study). But that's not all. Insulin can also help us directly on muscle building.

Insulin is one of the most anabolic hormones in our organism. It increases muscle protein synthesis (study), and it inhibits proteolysis.

If carbohydrates stimulate insulin secretion and insulin can consequently help us improving performance and muscle protein synthesis... maybe carbohydrates are not that bad after all!

Carbohydrates Timing

Now we have talked about what carbohydrates are and how they can help our metabolism. But when should we eat them? What's about carbohydrates timing?

As a general rule, the best times for carbohydrate intake are:

  • Pre-workout
  • Intra-workout
  • Post-workout
  • Night time

Depending on our goal, the carbohydrates timing may slightly differ. In the following section we'll review each of the situations in which carbohydrates timing and chrononutrition may play a role.

To Lose Weight

If you want to lose weight, nutrition is important. It provides the correct energy status to induce fat oxidation and consequently lose weight (study).

Following the CICO model, total energy intake along the day is what matters the most for weight loss. However, there are other factors affecting the process.

Carbohydrates are sources of fibre, improving your gut microbiota and keeping you satiated for longer (study). For this reason, we may benefit from carbohydrates intake on a meal prior to a fasting period (e.g: night time).

Because muscle protein synthesis and performance are compromised during a  weight loss phase, carbohydrates intake 2-3h before workout can help you delaying muscle fatigue and improving performance (study).

In terms of weight loss and carbohydrates timing, results are quite controversial. While some studies show carbohydrates in the morning to favour weight loss (study), some others show the opposite (study). This suggests that, although carbohydrates intake may affect weight loss, it's the total energy intake what determines if we lose weight or not.

carbohydrates timing

To build Muscle

Carbohydrates induce insulin secretion, one of the most anabolic hormones (study). Thus, high levels of insulin post-workout may help achieving a greater anabolic response.

Although protein by itself can also induce insulin release (study), glucose is much better at doing the job. Carbohydrates post-workout can, therefore, help you build muscle (study).

When we are trying to build muscle, calorie intake is usually high. Because fat and protein intakes are established within a recommended range, carbohydrate is the most versatile component of our diet. This is, the higher the calorie intake, the higher the carbohydrates intake. Because of the excess of this macronutrient, carbohydrates timing is not as important as it is when you try to lose weight. 


To Optimize Recovery and Performance

Carbohydrates timing play a central role on muscle recovery and training performance.

Training is a compromising activity for our metabolism. It requires of large amounts of energy, coming from different energy systems. Carbohydrates intake after the trainig session can help you refilling glycogen stores (study) and optimizing muscle recovery (study).

Carbohydrates pre-workout can also improve your training performance (study). By increasing blood glucose and glycogen stores, it delays muscle fatigue and lowers percieved exertion during exercise.

Following Intermittent Fasting

Intermittent fasting is a popular protocol alternating between eating and fasting periods (study). Its potential benefits on health and body composition have made it one of the most following nutritional protocols.

During the fasting period, all calories and foods are restricted. If we are training during the fasting period, carbohydrates intake as soon as you enter your eating window may be important in this case.

Intermittent fasting protocols are usually low in carbohydrates. However, you can perfectly follow a high-carbohdyrate intermittent fasting. In this case, focus on getting your carbohydrates close to the training session, and high-fibre sources on your last meal before the fasting period.


Carbohydrates timing is a fact to consider in our diet. Although carbohydrates are non-essential, they are still important for our metabolism and energy production.

In this post we reviewed the best times to take carbohydrates: close to exercise and before bed. However, these general recommendations differ depending on our situation.

If you have any doubt or question, leave it below in the comments section!

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