Protein and amino acid supplementation enhance muscle size and strength

In my life and work I commonly come across men who are keen on being stronger and more muscular, and will ask about the sort of diet that might help them achieve their ends. Perhaps not surprisingly, I recommend a diet relatively rich in protein, seeing as protein is a major component in muscle. For those keen to go the extra yard, I do think that some protein supplementation may be in order, usually in the form of whey protein concentrate consumed around the time of exercise.

I was interested to read a recent study in which the effects of whey protein in combination with the amino acid leucine on physical performance and body composition in ‘moderately fit’ individuals [1]. Leucine is an amino acid (building block of protein) that is believed to have particular value in stimulating the formation of muscle.

In this study, individuals were randomly assigned to consume about 20 g of whey protein and 6.2 grams of leucine each day, or a ‘placebo’ (which did not contain whey and leucine but contained the same number of calories). The study lasted eight weeks.

In the whey/leucine group, significant improvements were seen in performance in the bench-press (pushing weights up with the arms while lying down). Press-up (push-up) performance was also improved. These improvements were not seen in the group consuming the placebo.

On the other hand, no improvements were seen in other measures including crunches (a form of sit-up), chin-ups or the time taken to run 3 miles.

Each of the study participants was assessed for body composition at the start at the end of the study. The group consuming the whey/leucine supplement saw gains in body weight and lean body mass (a measure of muscle mass). No such changes were seen in the group supplementing with the placebo.

The authors conclude that “supplementing with whey protein and leucine may provide an advantage to people whose performance benefits from increased upper body strength and/or lean body mass.”


1. Walker TB, et al. The influence of 8 weeks of whey-protein and leucine supplementation on physical and cognitive performance. Int J Sport Nutri Exerc Metab. 2010;20(5):409-17

5 Responses to Protein and amino acid supplementation enhance muscle size and strength

  1. Brian Abbott 4 February 2011 at 4:21 pm #

    Is Casein protein better than Whey protein to increase muscle mass?

    Why is it so difficult to get unsweetened protein powder?

  2. R.DAndrea 4 February 2011 at 9:56 pm #

    What about men with diminished Kidney function. Can they take Whey protein. My husband has 60% kidney function from years of NSAID use(never exceded recommended dose)due to back pain.
    He is supposed to limit protein intake and so has lost muscle mass.

  3. Anyanwu John Benson 4 February 2011 at 10:37 pm #

    Diabetics generally are deficient in lean muscle mass. From the above blog it is very clear that diabetics can benefic significantly from taken whey protein, provided added sugars and other additives are out of the picture. Diagestion is also one of the problems of diabetics and once the lean muscles are in place diagestions are enhanced.This in effect means insulin sensibility,
    and insulin sensilibility increases glucos intake in the body.

  4. Richard 5 February 2011 at 2:30 am #

    Whey protein is also a source of growth factors, like IGF 1 (Insulin like Growth Factor 1). How much did this contribute to muscle growth?

    Adding 2 litres of cows milk per day to your diet, in conjunction with weight training can elicit fast weight gain, search Timothy Ferris’s 4HWW blog for more detail. Not sure this is a good idea though considering the association of acne and cancer… with dairy consumption, maybe okay for short term use?


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