Protein is being hailed as the answer to all our dietary woes these days. Lose weight? Eat protein. Bulk up? Protein.
Bodybuilders and athletes were on the protein tip long before it became the diet du jour, and additionally, are well aware of the effects of various amino acids, particularly the branched chain amino acids, leucine, isoleucine and valine. Present in high quantities in dairy proteins like whey, these amino acids are known for their muscle building ability.
We have all heard about insulin resistance – a state where the body's response to insulin decreases that often precedes the development of type II diabetes. It can be related to a number of factors, but the chronic overconsumption of refined, high GI carbohydrates is a major contributor.
How do these two things fit together? Well it has been shown that like sugars, BCAAs also stimulate the release of insulin, which is a powerfully anabolic hormone. This pathway is responsible for many of the muscle building properties of BCAAs. This has left many people wondering if a high intake of protein has any long term effects.
This has been studied extensively by many different groups. A team of European researchers has recently compiled all the data that has been generated so far and drawn some very interesting conclusions.
Firstly, there is a lot of evidence telling us that a high protein intake and increased intake of BCAAs lead to an increased risk of type II diabetes. Although the group found that people with higher protein intakes develop type II diabetes more often, interventional studies where scientists attempted to rectify this, presumably by placing trial participants on low protein diets, did not generally change the diabetes risk in these populations, and in some cases increased insulin resistance. This is an unexpected result, as we know that reducing levels of refined carbohydrates can reverse insulin resistance and diabetes progression, and we would expect protein to do the same thing.
These conclusions show that the relationship between protein intake and insulin resistance is complex and may be subject to other factors and variables. It will be interesting, in time, to find out what these are.
What we do know is that protein has enormous benefits for many people, and is a vital part of a balanced diet, which along with regular exercise, is the key to long term good health.
Rietman A, Schwarz J, Tomé D, Kok FJ, Mensink M. High dietary protein intake, reducing or eliciting insulin resistance? Eur J Clin Nutr. 2014 Jul 2.