STOCKHOLM – Shivering upon repeated short exposures to cold improves glucose tolerance, decreases fasting blood glucose and lipid levels, and markedly reduces blood pressure, show new study results in adults with obesity and overweight.
Presenting the preliminary findings at the annual meeting of the European Association for the Study of Diabetes, Adam Sellers, a PhD student from Maastricht (the Netherlands) University, said: “The results are highly promising and may eventually suggest an alternative treatment or preventative measure for type 2 diabetes.”
Dr. Sellers found that 10 daily 1-hour sessions of shivering at 10° C led to 85% of participants showing a drop in fasting glucose, and a 32% drop in lipid levels, as well as a blood pressure drop of around 8% overall.
Although cold exposure is known to increase brown fat, Dr. Sellers doesn’t believe this explains his findings. “This research, in addition to two other prior studies, suggest that shivering and skeletal muscle may play a more important role than brown fat,” he said.
“Muscle can contract mechanically – [the concept of the] shivers – thereby generating heat, and there is considerably more muscle than brown fat in a human, so shivering can burn more calories and produce more heat,” he explained.
He added that, in the future, “in a similar way to saunas and steam rooms, there might be cold rooms where people go and sit in the cold room and shiver, or possibly patients attend hospital and shivering is induced.”
Audience member Anna Krook, PhD, professor of integrative physiology at the Karolinska Institute, Stockholm, commented on the work, saying the results are “potent” and demonstrate the metabolic effect of shivering. “One thing that struck me was, given the time the subject had to spend – 1 hour shivering over 10 days, I wonder if 1 hour of exercise would show similarly potent effects, and perhaps for those people who cannot perform exercise for whatever reason this might be a good alternative.”
She pointed out that, in terms of translation into practice, it “really depends on how tolerable this is. It also shows how important our muscle is in regulating metabolism. The study showed that you had to be shivering, and it wasn’t just enough to be cold, which has implications for the role of brown fat, especially when we consider the small amount of brown fat we have compared to muscle, which can be half of body weight.”
And Denis P. Blondin, PhD, said: “The reality is that we know it can be difficult and even painful for individuals with obesity to perform exercise, and therefore, cold exposure offers a passive way of improving our metabolic profile and cardiovascular health.”
“Some will argue that it is unrealistic to propose cold exposure as a therapy, but people overlook the fact that cold exposure [mostly through cold-water immersion] has increased in popularity over the past 5 years and has also been a cultural staple for many Nordic countries, albeit often performed with heat exposure as well [see the use of saunas and cold-water swimming in Finland and other Nordic countries],” added Dr. Blondin, of the faculty of medicine and health sciences, University of Sherbrooke (Que.)
“While it can certainly be uncomfortable at first (like starting an exercise program), we adapt very quickly,” he added.