Why is Protein Essential?

Updated: May 15, 2020

Contents of the article

1. Introduction

2. Type

3. Timing

4. Amount

5. Summary


No matter what your fitness goal, protein will play a huge role in helping you achieve it. Protein is essential for muscle growth and without sufficient protein your muscles will not increase in size. Protein can also aid with weight loss as it has a satiating effect (makes you feel full for longer), resulting in less calories being consumed to ensure a calorie deficit. Additionally, studies have shown the positive impact protein plays in injury recovery, lowering blood pressure, and boosting metabolism (thermic effect). The type, timing and amount of protein required will be discussed in this article along with other helpful tips that may give you that final push to help you hit your goal.


When discussing type of protein we don't mean chicken or mince, instead we are focusing on whey, casein and soy to help supplement our protein intake each day. Following strength or endurance training, consumption of whey protein is optimal compared to soy and casein. When compared to soy and casein, whey shows a higher myofibrillar fractional synthesis rate, which is linked to muscle protein synthesis. This is illustrated in figure 1, which is taken from Tang et al's study in 2009. Muscle protein synthesis is the process in which damaged muscle is repaired, typically following a workout resulting in muscle growth. Therefore, having a higher muscle protein synthesis rate is essential to elicit hypertrophy (growth of a muscle). Additionally, whey protein has a higher leucine content and this leucine is elevated for longer following consumption of whey compared to casein and soy. Leucine is an essential amino acid that is important for protein synthesis and therefore muscle growth.

Figure 1. Comparison of whey, casein and soy consumption on myofibrillar fractional synthesis rate at rest and following exercise.


Following a training session or workout it can be difficult/ too much effort to cook a meal to ensure you are getting sufficient protein for recovery. So how long after a session should we consume protein? Studies suggest that consuming whey protein < 30 minutes after training increases the rate of muscle protein synthesis and this increase is for up to 48 hours post exercise. Figure 2 shows consumption of protein in this 'anabolic window' (< 30 mins post exercise) results in a prolonged increase in rate of muscle protein synthesis. This will enhance muscle recovery causing an increase in muscle adaptation. Whey protein shakes are a great way to ensure you're consuming protein during this anabolic window to optimise muscle growth.

Figure 2. Impact on rate of muscle protein synthesis when consuming protein 30 mins after exercise (Burd et al., 2009).

Casein is slightly different when compared to whey as it is a slow release protein. This property makes it perfect for consuming before sleep to ensure muscle recovery throughout the night. A study by Res et al, (2012) identified plasma leucine concentrations to be higher over an 8 -hour period, and we know that leucine is important for muscle protein synthesis and hence muscle adaptation.


The amount of protein we consume each day is essential to muscle adaptation as you cannot increase muscle mass without protein. Individuals that train to increase muscle size/ strength should consume approximately 2g/kg of body weight of protein per day. For example a 75kg individual should consume 150g of protein per day. This protein is utilised most efficiently when consumed in 4 different servings throughout the day. This could be at breakfast, lunch, tea, and before sleep. Figure 3 illustrates this point as Areta et al, (2013) looked at eating the same amount of protein 2x, 4x and 8x per day. Consuming protein 4x per day showed a significant increase in myofibrillar fractional synthesis rate compared to 2x and 8x per day. This result sin a higher rate of muscle protein synthesis and hence greater muscle recovery/ adaptation.

Figure 3. Impact of protein consumption 2x per day (black), 4x per day (grey), and 8x per day (white) on myofibrillar fractional synthesis rate.

As stated above the optimal time to consume protein is < 30 mins post exercise. But how much protein should we consume post exercise? The optimal amount of protein to be consumed post exercise is 40g. MacNaughton et al, (2016) showed 40g of protein to be superior to 20g of protein to increase myofibrillar fractional synthesis rate, which is linked to muscle protein synthesis and hence muscle adaptation. This graph is shown in figure 4.

Figure 4. Comparison of 20g and 40g of whey protein on myofibrillar fractional synthesis rate post exercise.


The main points to take away from this article are that protein is essential to muscle growth and weight loss. To enhance this muscle growth it is optimal to consume 40g of whey protein within 30 minutes post exercise. Throughout the day a total of 2g/kg of body weight of protein should be consumed across 4 separate meals to enhance muscle protein synthesis and enhance muscular adaptation. Whey protein and casein should be used to supplement protein intake where not enough protein is being consumed through daily nutrition alone. A typical day may look like this; breakfast (30g protein), lunch (40g protein), tea (40g protein), train in evening and consume 40g protein (whey protein shake) within 30 mins after the session. This is an ideal scenario and obviously not everyone can follow this exactly, but make sure to consume adequate amounts of protein each day to optimise your muscle growth!


Areta et al, (2013)


Burd et al, 2009


MacNaughton et al, (2016)