Metabolic Window – Truth or Myth?

metabolic window

Is metabolic window real, and is there any evidence? Yes, it is, and after training, which leads to the depletion of glycogen reserves, muscles for several hours are especially active in replenishing its reserves. This is due to the increased activity of the enzymes responsible for the synthesis of glycogen, and if in the normal state the rate of synthesis is approximately 25 g / h, then in the first hour after training, it is 100% higher than at rest. But after 2-3 hours the speed decreases and returns to normal, the window closes.

The science about metabolic window

Thus, after eating 100 grams of fast-digesting carbohydrates after a workout, you will send them to the muscles, and after a few hours – the same amount may be partially sent to fat. The keyword – “may be,” because with a diet with a calorie deficit – it does not matter because we know that the balance of body fat = stored fat – burned fat. So, based on this recommendation, eating simple carbohydrates immediately after a training session seems extremely logical, because complex ones just do not have time to digest.

Is it necessary to close it?

metabolic window after workout

Recommendations for taking carbohydrates after training are extremely relevant for athletes of cyclic sports because of the often-repeated (4-5 times a week) voluminous workouts (2-3 hours), as well as for crossfiters. Agree that if a cyclist has traveled 70-80 km for training and the next day he will have the same thing, then without proper replenishment of energy reserves after the first day, he is unlikely to workout qualitatively on the second.

In terms of stimulating muscle growth, the intake of carbohydrates after exercise does not have any advantages, unlike the use of amino acids (protein) or the intake of amino acids with carbohydrates.

Reasoning on this topic, as we wrote above, is not relevant for deficient calorie content, because the distribution of carbohydrate intake is due to the maintenance of training performance and household activity. What does it mean?

metabolic window myth

For example, you train according to the upper-lower body scheme, i.e., today, the lower body, and tomorrow the upper, and it is clear that after training the top part, the reserves of muscle glycogen in the lower body decreased slightly. In this case, the rate of glycogen replenishment is not so important, because even if the next workout is tomorrow, it will be for lower-body. It is completely different from full body training when the same muscles are loaded on each workout.

With surplus (mass gain/bulking), the distribution pattern is different, because excess calories provided by carbohydrates can be accumulated in both muscle and adipose tissue.

Additionally, see why calorie calculators and formulas don’t work.

What is more, why not read the article about how to weigh products correctly?