A group of scientists from the Netherlands have published some studies in the past 10 years about the effect of cold on metabolic health. Their first study published in 2015 showed that exposure to cold (14-15oC) for 10 days up to 6h/day in type 2 diabetic patients (n=8) can improve insulin sensitivity by increasing brown adipose tissue mass and activity. In the second study in 2021, they exposed nine type 2 diabetic individuals to cold (15-16oC) but avoided shivering by providing them extra clothes till the shivering stopped. Surprisingly, no change in metabolic health was observed, indicating the importance of shivering or muscle contraction in improving metabolic health.
In their recent study published in the Nature Metabolism journal in December 2024, they determined whether shivering can improve the metabolic health of obese people, thereby preventing obesity-related metabolic disorders. 15 obese adults (11 males and 4 females) were recruited, 9 of whom were glucose intolerant. 10 days of cold exposure(10oC) of 1h per day improved the oral glucose tolerant test by 6% with a 3% reduction in fasting blood glucose levels. Out of 9 glucose-intolerant individuals, 4 became tolerant at the end of the study. Furthermore, shivering reduced the blood levels of free fatty acids and triglycerides by 11% and 17% respectively. Also, blood pressure was reduced in all patients, indicating the benefits of shivering.
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Limitations of the study
- This study was a single-arm due to feasibility. However, a randomized controlled design would be appropriate to establish causation.
- Although the participants were given standardized diets and their physical activity was monitored, their lifestyle outside the study site was not fully controlled.
- The differences in total energy expenditures and shivering intensity could lead to inter-individual variation.
In conclusion, cold exposure along with shivering can improve the metabolic health of obese people by improving blood glucose and cardiovascular markers, highlighting the significance of lifestyle change in avoiding obese-related metabolic disorders.
