You Should Really Cut Down On The Protein Shakes – Here's Why

As with anything, especially nutrition, the golden rule is variation and moderation. wavebreakmedia/Shutterstock

Muscleheads and Instagram fitness influencers, you might want to take a second look at your protein shakes and bulking-up snack bars.

Amino acids, the building blocks that make up proteins, are essential for life and they’re especially important if you’re looking to bulk up. However, a new study on mice has thrown light on the negative side effects of over-using super-high-protein supplements.

The research, published in Nature Metabolism, suggests over-consuming branched-chain amino acids (BCAAs) – a common component of protein shakes and other weight-gain supplements – could result in unwanted weight gain, negatively affect your mood, and even shorten your life.

As with anything, especially nutrition, the golden rule is variation and moderation. The study’s authors argue that their work highlights the importance of mixing up protein sources to get a variety of essential amino acids. 

BCAAs are most plentiful in red meat and dairy, although there are also found in poultry, fish, and eggs. Vegetarians can also naturally obtain good levels of BCAAs from beans, lentils, nuts, and soy. Along with containing more vitamins and minerals, these natural sources of protein also contain a wider array of amino acids that are essential for life and muscle growth. 

"While diets high in protein and low in carbohydrates were shown to be beneficial for reproductive function, they had detrimental effects for health in mid-late life, and also led to a shortened lifespan," Dr Samantha Solon-Biet, from the Charles Perkins Centre at the University of Sydney in Australia, said in a statement.

"What this new research has shown is that amino acid balance is important – it's best to vary sources of protein to ensure you're getting the best amino acid balance."

To reach these findings, the researchers fed groups of mice diets containing different amounts of BCAAs: either double the typical intake, the standard amount, half the normal intake, or a fifth of the normal amount. The mice on a double BCAA diet were all found to suffer from obesity and a shorter lifespan.

Bear in mind, this is an extremely high level of BCAAs to eat and this study only looked at the effects on mice. Nevertheless, the research does neatly highlight that supplementation of BCAAs can lead to other essential amino acids, such as tryptophan, being out-competed for transport to the brain. In turn, this could cause a tryptophan deficiency and a whole bunch of problems related to mood and wider health. 

“Tryptophan is the sole precursor for the hormone serotonin, which is often called the ‘happiness chemical’ for its mood-enhancing effects and its role in promoting sleep. But serotonin does more than this, and therein lay the problem," explained Professor Stephen Simpson, Academic Director of the Charles Perkins Centre.

“This then lowered serotonin levels in the brain, which in turn was a potent signal to increase appetite. The serotonin decrease caused by excess BCAA intake led to massive overeating in our mice, which became hugely obese and lived shorter lives.”



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