Fitness Myths: The Post-Workout Protein-Carbohydrate Window

Last Thursday, when I barely made it to my protein shake within that sacred 30-minute post-workout window? Racing against the clock, I wondered: is this frantic dash really necessary? It sparked my curiosity, and I decided to turn myself into a guinea pig for a week. That’s right, I experimented with different post-workout eating times to see if this whole ‘protein-carbohydrate window’ theory holds any water. Join me as I share the surprising insights from my personal journey and delve into what science says about this widely debated topic. Are we all just chasing our tails, or is there a nugget of truth in this race against time? Let’s find out together.

Is there a protein-carbohydrate (anabolic) window after a workout?

The main idea is this: after a strength workout, your muscle fibers are damaged and glycogen stores depleted. Consuming a mix of proteins and carbohydrates as soon as possible after a workout is thought to compensate for these effects, allowing your body to quickly build more muscle. This magical state is believed to last only 30-40 minutes, after which the window closes, and those who miss it are too late. Without taking advantage of this anabolic window, you won’t build muscles, and your workout will be wasted.

Novices, influenced by the sports nutrition industry, often fall into this trap, adopting the dietary regimes of elite, steroid-using athletes.

Anabolic Window – Only After Fasting Workouts

One idea behind the “anabolic window” is the accelerated muscle breakdown post-workout, which needs to be quickly halted. In reality, muscle breakdown rates after strength training are only slightly elevated. Hence, immediate post-workout meals don’t play a huge role.

The exception is for fasting workouts, where you haven’t eaten for 4-5 hours or more. In this case, muscle protein breakdown significantly increases, so eating right after a workout is a good strategy.

Furthermore, all studies showing the existence of the protein-carbohydrate window were conducted on athletes who trained on an empty stomach.

Therefore, what and when you ate during the day before the workout is crucial.

Food digests slowly, and an empty stomach doesn’t mean there are no nutrients in your blood. They continue to enter the bloodstream for 4-5 hours after eating. So, if you ate 2-3 hours before the workout, you already have proteins and glucose in your system, and eating something before and immediately after the workout isn’t necessary.

If possible, eat something protein-carbohydrate based right before the workout. Not only will you get some amino acids in your bloodstream, available during and immediately after the workout, but a small amount of carbohydrates will ensure stable glucose levels and enough energy. This option also works for those who can’t eat right after a workout.

If you start a workout fasting (more than 3-4 hours after your last meal), consume 25-30 grams of protein right after the workout.

If it’s been 3-4 hours since your last meal, consume a mix of proteins and carbohydrates 30 minutes before the workout to normalize blood glucose levels and get some amino acids: 0.3-0.5 g/kg of both proteins and carbohydrates is a good starting point. Post-workout: 0.3-0.5 g/kg of protein and 0.3-1.5 g/kg of carbohydrates.

Therefore, if your last meal was 2-3 hours before the workout, your body is still using the consumed amino acids for muscle repair and growth.

In 2013, a comprehensive review of studies on the “anabolic window” was conducted.
One of the main findings was that there’s no convincing evidence that consuming carbohydrates and proteins immediately after a workout increases muscle protein synthesis.

When it came to building lean muscle mass, the timing of protein intake didn’t matter. In all studies where participants consumed protein immediately after a workout, results were slightly better, simply because they consumed more protein throughout the day.

Anabolic Window Lasts 24 Hours

According to a study by the Department of Kinesiology at McMaster University, Hamilton, Ontario, protein synthesis is elevated for 24 hours after a strength workout.

Muscle protein synthesis in the human body increases by 50% four hours after a strength workout and by 109% after 24 hours, then quickly decreases, returning to baseline levels after 36 hours.

Thus, what you eat during 1-2 days after a workout is important, not just within half an hour after it. The total amount of protein and carbohydrates consumed throughout the day is crucial. Exceptions may include only elite athletes or people who train multiple times a day, as well as those who train on an empty stomach.