Protein is a contentious subject in the dieting conversation. Personally, I'm vegan, and whenever my diet comes up with someone I'm meeting for the first time, their first question is, invariably, "But where do you get your protein?!" They never believe me when I say I meet my protein quota with plant sources and that excessively high protein diets are simply trending right now in the weight loss world. It also never fails to strike me as odd when strangers seem so concerned with my nutrition—that is until I remember that it's not my personal health they're worried about. When people question others' food choices, it's simply a way to validate their own.
But I digress. The point here is that in our modern age of Paleo and gluten-free, protein is a hot-button topic.
In fact, brand new research out of the Washington University School of Medicine in St. Louis has something more to add about the potential effects of a high-protein diet. While experts accept the idea that high-protein foods are beneficial for weight loss, they were interested to see how a protein-heavy eating plan affects other aspects of our health. What the authors of this study found was a bit troubling.
To find out how a high-protein diet might be damaging to your health, read on.
Here's how the study worked: For six months, researchers tracked 34 women who were postmenopausal and struggled with obesity. According to a report from Time, the subjects were separated into three groups: a control group that didn't change their diet, a group that went on a calorie-restricted diet (including "the daily recommended amount of protein"), and a group that went on the same diet but with increased protein.
Both groups of women on weight loss diets were able to reduce their body weights by approximately 10%. The main difference is that the women on a normal-protein diet "experienced a 25 to 30% improvement in insulin sensitivity," an operation that is essential for overall health. By contrast, the women on a high-protein diet experienced a complete stop to insulin sensitivity function.
What does insulin sensitivity do, exactly? According to CoachCalorie.com, high insulin sensitivity is important because it allows you to eat carbohydrates without your insulin levels spiking. This facilitates fat loss and protects the body from developing type 2 diabetes. "People that have bombarded their bodies with high-glycemic carbohydrates and processed foods over their lifetimes have become somewhat resistant to the effects of insulin," says CoachCalorie.com. "Therefore, when they eat carbohydrates, it causes a larger release of insulin." This is dangerous for the metabolism.
What the authors of this new study found is that high-protein dieters experienced some of these same deleterious effects of insulin sensitivity. “We definitely expected a blunting of the effect," said Bettina Mittendorfer, the study's lead author. "But to completely eliminate it was a little bit surprising."
The study's sample size was small, so more research is needed to fully understand its findings. But Mittendorfer assures that this is not the first time high-protein diets have been associated with a risk for type 2 diabetes, and she advises dieters to proceed with caution.
"I think there is no reason to go for high protein intake during weight loss, based on our results," she told Time. "There’s no reason to do it, and potentially there is harm or lack of a benefit."
Instead of going high-protein for weight loss, try one of these seven legitimate weight loss tips we learned from extreme diets. Or try one of our favorite plant-based cookbooks, Clean Green Eats.