What is the difference between slow and fast proteins?

Protein is the key to building muscle after a workout. Here’s what you need to know about protein intake.

 Yogurt  (photo credit: INGIMAGE)
Yogurt
(photo credit: INGIMAGE)

There’s a difference between "slow" proteins, which are recommended to be consumed in food or drink before bed and "fast" proteins, which will do the work for you after you exercise. How can you choose the right one and which products do you need to know about before the next workout? Here are the answers.

Adequate protein intake is crucial for our health. It contributes to muscle mass and bone health, and also helps us maintain a healthy weight. Since awareness of proper protein intake has increased in the last few years, companies started marketing new protein-rich products, such as yogurts, milk drinks, protein bars and protein powders.

But what exactly should you consume and how do you choose? 

Let's organize all the information you need.

Proteins are made up of chains of amino acids. There are 20 of these, and our body needs them all. The difference between the proteins is in the number of amino acids in the chain, their type, the order of their connection and the spatial structure in which they’re organized. 

Of the 20 amino acids, the amino acid leucine was found to be most effective for consumption after physical exertion, as it contributes to the repair and renewal of muscle tissue damaged during physical exercise, even slight tears which occur on a regular basis.Proteins are found naturally in milk and dairy products, meat and meat products, eggs, soy and legumes. Proteins differ according to the rate of their absorption in the body. 

With "slow" proteins the rate of increase of amino acids in the blood is slow, and with "fast" proteins the rate of increase of amino acids in the blood is fast. "Slow" proteins, such as casein protein, should be consumed when the time window for building muscle is long, for example before bed. "Fast" proteins, such as whey and soy, are recommended for consumption when the time window for building muscle is short, such as at the end of a workout or between workouts.

There are many points to consider when choosing the protein product we want to eat or drink in different situations: is it part of a meal, something to meal after a workout, or a late night bitetaste, type, quantity, quality, availability, etc. 

If you want to consume protein after physical exertion, nutritionists recommend 20-40 grams of whey protein, which contains one-three grams of leucine. Cow's milk naturally contains about 80% casein protein and 20% whey. When dairy products are produced changes in the protein content can be made which affects the amount and type of protein in the products.

A protein that has undergone an isolation process will contain the highest amount of whey protein and the highest amount of the amino acid leucine. So, it will be the most recommended protein to consume after a workout. Today, you can find a variety of protein drinks that differ from each other in the process of protein production in nutritional values, which vitamins and minerals are added and in how they taste.

Rakefet Arieli is a clinical and sports dietitian at Shaare Zedek Hospital Sports Medicine Center. This article was written in cooperation with Yotvata and was published on our sister publication, Maariv.