Everyone knows that a high-protein diet is the best approach for nutrition, the benefits are well known by even the nutritional novices out there.
But what about the benefits of whey protein? This is the stuff that makes up the majority of protein shakes (with casein being a distant second), but why whey?
In this article we are going to outline the main benefits of a high-protein diet before looking at the specific benefits of taking whey protein.
You can split the benefits of a high protein diet into two main groups; exercise-related and non-exercise-related. The first group is mostly of interest to gym goers, bodybuilders, and amateur/professional sports men and women. The second group is of interest to everyone who wants to lead a healthier lifestyle and improve their physique.
So how does protein benefit people who exercise regularly? Well there is a process known as muscle protein synthesis (MPS) in which damaged muscle fibres are repaired, strengthened, and enlarged via dietary protein. Whenever you contract a muscle, the fibres that contracted become damaged, the more intense the workout the more muscle damage occurs.
It is for this reason that athletes require double the amount of protein in their diet than sedentary people . If you perform an exercise and you don't have sufficient protein to rebuild and strengthen the muscles (known as anabolism) the muscles may break down further (known as catabolism).
For muscle growth to occur, muscle protein synthesis must outweigh the rate of muscle protein breakdown . It is for this reason that so many people believe that protein should be taken immediately post workout. In actual fact it is not nearly as vital as that as the ‘anabolic window' can actually last several hours.
People forget that if you say trained at 3pm you would still have a lot of stored protein in your system from lunch, which would tide you over until dinner. If however you have been training fasted (because you're crazy!) it would be beneficial to take protein immediately post-workout .
For people who are already getting enough protein in their diet, there is no need for pre or post-workout shakes . But as so few of us rarely do get enough protein in our diet, it might be a good habit to get into.
Interestingly the effects of exercise can last up to 48 hours afterwards, meaning that it is necessary to keep your protein intake high even the day after a session . In this case, protein shakes are as good a source as any.
Now that we have seen why protein is crucial for regular exercisers, we can look at the effects it has on the physique and body composition of both exercisers and non-exercisers. If you are dieting, protein is very effective at preserving lean body mass (muscles) whilst in a calorie deficit . This prevents muscle loss, and is crucial for people who are ‘cutting'.
A study by Layman et al (2003) found that increasing protein and lowering carbohydrates led to improved body composition . There are many reasons for this, protein has been shown to increase thermogenesis, improve satiety (making you feel full after food), and as a result of that lead to weight loss . The lowering of carbohydrates isn't because carbohydrates are “bad” but just coming from a need to lower overall calories. Also, many diets consist of much more carbohydrates than needed.
Now a lot of the benefits of whey are down to it being a form of protein, so some studies will say that whey protein can lead to weight loss  but it doesn't necessarily mean that it was solely due to the whey itself.
A study by McGregor & Poppitt (2013) looked into the effect of milk protein on metabolic health – Whey protein and Casein protein are both ‘milk proteins'. The study found that not only was there a significant improvement on metabolic health, that milk proteins could lower the risk of Type II Diabetes .
Another study, this time by Jakubowicz & Froy (2013) also found that whey protein could help “combat obesity and Type II Diabetes” through increased thermogenesis, improved satiety and its effect on the release of certain hormones (including insulin) . As mentioned earlier, this may be due to whey being a source of protein, rather than a specific benefit of whey itself.
The next few studies were all performed on elderly men, for some reason an absolute tonne of research into the effect of whey protein on the elderly has been done. Luckily there isn't much difference in results between an elderly man and a 20 year old man/woman.
It seems that the elderly may require slightly higher doses of whey protein post workout as ageing seems to have an effect on anabolism (growth) . The study that found that, praised whey protein as it is much faster digested than other proteins.
A study by Witard et al (2013) found that whey protein stimulated amino acid oxidation, which is responsible for an increase in metabolic energy . They stated that a 20g dosage was ideal (for elderly men) whereas a study by Pennings et al in 2012 stated that 35g was correct .
The Pennings study is great because it looks into the effect of whey protein in addressing the poor nutritional habits of the elderly. In the study they state that elderly men tend to have very low protein meals for breakfast and lunch, whilst their dinners contain around 35g . They say that adding whey protein to breakfast and/or lunch can help boost protein and lead to a much more even distribution.
This is reminiscent of the findings by Mamerow et al (2014) who stated that protein intake should not be skewed to dinner but shared out equally amongst meals for optimal protein synthesis to occur .
Finally a study by Burd et al looking into whether Whey or Casein protein was better, found that whey protein produced better MPS both after exercise, and after a rest day . This is probably due to how quickly whey protein can be absorbed.
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Matt Smith is a fitness and nutrition writer with more than 10 years experience as a personal trainer, and a degree in Sports Science from London Metropolitan University. He has written for many fitness websites, and runs his own blog and podcast at beernbiceps.com