The carbohydrate (or metabolic) window is the time after physical training during which the body is most sensitive to incoming proteins and carbohydrates. The energy obtained from the nutrients consumed at this time is spent mainly on muscle recovery and growth.

The carbohydrate window opens immediately after the end of strength training and lasts from 45 minutes to 2-3 hours. In the first phase of the carbohydrate window, sports supplements in the form of whey protein isolate, fast carbohydrates and creatine are recommended, in the second phase – a full meal.
Fast carbs after a workout
Strength training stimulates the production of cortisol, lowering testosterone, growth hormone and triggering the mechanism of muscle breakdown into amino acids). Taking 1-2 g of BCAAs during training blocks these processes, and taking fast carbohydrates immediately after training turns their back.

Carbohydrates with a high glycemic index dramatically increase the level of insulin in the blood, blocking the negative effects of cortisol. Insulin, in turn, opens up the ability of cells to store energy. And since muscles need energy after training, they begin to actively receive it.

How much protein do you need after a workout?
Although bodybuilders believe that “the more protein, the better,” this is not supported by science. First, excessive protein intake can lower testosterone levels. Secondly, the body simply ceases to absorb excess proteins from sports nutrition, removing them with urine.

A growing body of research suggests that 15-25g of whey protein immediately after a workout is enough to easily cover the need for the most important amino acids. The overall balance of nutrients in the daily diet is more critical, although it should also contain about 1.5-2.5 g of protein per kg of dry body weight.

Do I need to take a gainer?
Gainer is a mixture of whey protein and fast carbohydrates. Consuming a protein/carbohydrate shake like this immediately post-workout causes weight gain—however, whether you gain lean muscle or fat will be affected by the balance of nutrients in a particular brand of product.

Unfortunately, there is no unequivocal data on how many grams of carbohydrates per kg of body weight should be consumed. The numbers vary from 0.15 g to 0.6 g or even higher. It probably depends on characteristics of the athlete’s body (including his body type) and the total experience of strength training.

How many carbs do you need after a workout?
The minimum dose of carbohydrates is 0.15 g per kg of body weight – 10-12 g of fast carbohydrates for an athlete weighing 75 kg. This amount is enough to increase insulin levels and stop catabolic processes. If your goal is to quickly gain weight, increase carbohydrates to 30-40 g.

The meal following strength training should include a lot of proper carbohydrates, vegetables and various cereals – about 100-150 g. This will help replenish the glycogen stores spent during training (carbohydrates stored in muscles and which are the main source of energy for their work).
Proper nutrition for muscles
It is important to note that in most cases, the nutrients consumed before a workout are much more important than those consumed after it. If you come to the gym feeling hungry, it minimizes the effect of strength training – even if you close the carbohydrate window properly.

Maintaining a daily caloric intake (at least 2500-2700 kcal for a 70-75 kg athlete) and the right balance of nutrients (30-35% of calories from fat, 1.5-2.5 g of protein per kg of dry weight and about twice as many carbohydrates) is much more important for a set of muscle mass than a single cocktail after training.

Carb Window: Final Recommendations
To close the carbohydrate window immediately after a workout, you need 15-25 g of whey protein and at least 10-12 g of fast carbohydrates (the figure can rise to 30-40 g). At the same time, carbohydrates are also necessary for those who work to enhance the relief and are afraid to gain fat – however, at the minimum dosage.

A source of fast carbohydrates can be either a gainer or 100 ml of any juice or even fruit. One medium banana, for example, contains 30 g of carbohydrates (14 g of them are fast, 3 g are indigestible fiber). Adding 5 g of creatine to a shake will also have a positive effect on muscle growth.
Scientific studies show that after training, it is necessary to take not just protein, but mixtures containing proteins and carbohydrates with a high glycemic index. The main reason is that fast carbohydrates dramatically increase insulin levels, stopping catabolic processes.