With the advancement of modern technology, winter heating methods have become increasingly diverse. Recently, a research team from Maastricht University published a study in Nature Metabolism, exploring the potential health benefits of cold exposure and shivering. The study found that short-term cold adaptation and shivering significantly improve metabolic functions, especially for individuals who are overweight or obese, effectively enhancing glucose metabolism and improving blood sugar and lipid metabolism. These findings offer a new perspective on health interventions.
With the arrival of winter, northern regions enjoy centralized heating, while the south relies on air conditioners and heaters. However, some areas still depend on the traditional method of "freeze a little, shiver a lot" to stay warm. When stepping out from a warm indoor environment to the cold outdoor air, it’s not uncommon to feel a sudden chill and involuntarily "shiver." This discomfort caused by cold temperatures is something most people experience.
However, a recent study published in Nature Metabolism by a research team from Maastricht University reveals the surprising benefits of cold exposure and shivering. In their study, participants were intermittently exposed to cold environments for 1 hour each day, inducing shivering, and the results showed that cold adaptation combined with shivering can significantly improve several health indicators, including blood sugar, lipid metabolism, and blood pressure. This effect was particularly notable in individuals who were overweight or obese.
The aim of this study was to explore the long-term effects of repeated cold exposure and shivering on glucose homeostasis. The team recruited 15 overweight or obese adults, 9 of whom had glucose intolerance.
During a 10-day cold adaptation phase, participants were exposed to cold for 1 hour per day, inducing shivering, while the research team measured the impact of cold exposure on oral glucose tolerance test (OGTT) results. Various metabolic markers, such as fasting blood sugar, triglycerides, and non-esterified fatty acids (NEFA), were also measured.
The results indicated that 10 days of cold exposure with induced shivering significantly improved participants’ glucose metabolism. After cold adaptation, during OGTT testing, participants showed a 6% reduction in the area under the blood glucose curve (AUC), suggesting better overall blood sugar control. Fasting blood sugar levels decreased by 3%, and at the crucial 2-hour marker, glucose concentration decreased by 11%. These changes demonstrate that glucose tolerance was effectively improved. Notably, among those initially showing glucose intolerance, only 5 individuals still exhibited impaired glucose tolerance after the intervention.
Figure 1: Plasma glucose and insulin concentrations before and after cold acclimation
Cold adaptation also positively impacted lipid metabolism and blood pressure. The study found a 14% decrease in NEFA AUC, a 32% reduction in fasting triglycerides, and a 10 mmHg drop in systolic blood pressure and a 7 mmHg decrease in diastolic blood pressure.
Figure 2: Serum NEFA and triglyceride concentrations before and after cold acclimation
Figure 3: Resting blood pressure and heart rate before and after cold acclimation
These findings suggest that continuous cold exposure with shivering for 10 days can improve glucose tolerance and other metabolic levels in overweight or obese individuals. Moreover, researchers also noted that cold exposure and shivering led to muscle remodeling, which may help improve muscle health and function.
In a similar vein, earlier this year, a research team from the University of Granada in Spain published a study in Cell Reports Medicine, revealing unexpected benefits of cold exposure on metabolism.
After a series of screenings, the research team ultimately recruited 64 participants. They tested blood samples from participants before and 2 hours after cold exposure, focusing on measuring plasma signaling lipids.
The results showed that just 2 hours of cold exposure significantly increased levels of omega-6 and omega-3 polyunsaturated fatty acids and their derived oxidized lipids in participants' blood. Compared to pre-cold exposure, the levels of omega-6 fatty acids (such as linoleic acid, dihomo-γ-linolenic acid, and arachidonic acid) and omega-3 fatty acids (such as α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid) increased significantly, with an average increase of 46.9% and 77.4%, respectively.
This change was beneficial even for overweight or obese participants, though the most significant changes were observed in those within the normal weight range.
Figure 4: 2-hour cold exposure changes signal lipid levels
Further analysis revealed that the changes in omega-6 and omega-3 oxidized lipid levels induced by cold exposure were associated with healthier cardiovascular metabolic characteristics. 45% of the changes in omega-6 and omega-3 oxidized fatty acids were negatively correlated with fat content indicators such as BMI, waist circumference, and visceral fat index; 30% with glucose homeostasis parameters such as glucose, insulin, and insulin resistance homeostasis model assessment index; 60% with blood lipid indicators such as total cholesterol, low-density lipoprotein cholesterol, and triglycerides; and 35% with liver function indicators such as alanine aminotransferase and γ-glutamyltransferase.
In contrast, changes in eCBs (endocannabinoids), lysophospholipids, and sphingosine-1-phosphate due to cold exposure were not associated with cardiovascular metabolic risk factors. This study also indicated that these lipid molecule changes were mostly independent of brown adipose tissue (BAT).
Figure 5: Relationship between cold-induced changes in signal lipids and cardiometabolic risk factors and brown adipose tissue
Given that overweight or obese individuals showed a relatively lower increase in omega-6 and omega-3 oxidized lipids after cold exposure, it suggests that obesity may weaken the potential cardiovascular health benefits of cold exposure.
Overall, the study concluded that just 2 hours of cold exposure could significantly increase levels of omega-6 and omega-3 fatty acids and their oxidized products in the plasma of young individuals, which may positively affect heart metabolic health.
Summary
In conclusion, the health benefits of cold exposure are more significant than we might have expected, especially when the cold makes you involuntarily shiver—your body reaps even more benefits. Truly, "frozen beauty, freeze your way to better health!"
Of course, as this research is still in its early stages, larger-scale, longer-term clinical trials are needed to validate these findings and further explore the underlying mechanisms. Nevertheless, these discoveries offer new insights into how cold adaptation affects human metabolism and provide valuable scientific evidence for the development of new lifestyle interventions.
