Cold-induced metabolic flexibility explains ethnic disparities among individuals with obesity and insulin resistance.
Level 3 - non-randomized controlled study
Non-randomized comparative physiological crossover study
PubMed 41942741 · doi:10.1038/s41366-026-02066-7
What was done
Forty-one individuals with pre-metabolic or metabolic syndrome and overweight (31 Chinese, 10 Asian Indian; mean BMI 27.5 kg/m²) underwent whole-body indirect calorimetry following 1 hour of cold exposure (~14.5 °C) and an oral glucose tolerance test in a crossover design. Resting metabolic rate, respiratory exchange ratio, carbohydrate oxidation, fat oxidation, blood glucose, and insulin concentrations were evaluated.
What was found
No numerical values, effect sizes, or confidence intervals are reported in the abstract. Asian Indian participants showed significantly higher fasting insulin levels and lower insulin sensitivity than Chinese participants. Chinese participants exhibited a greater cold-induced increase in energy expenditure and a more pronounced shift in respiratory exchange ratio, carbohydrate oxidation, and fat oxidation. Cold-induced metabolic flexibility was independently associated with lower fasting insulin and lower insulin resistance in Chinese participants after adjusting for age, sex, and body fat; this association was not observed in Asian Indian participants.
Why it matters
This study highlights ethnic variation in thermogenic substrate utilization and suggests that cold-induced metabolic flexibility relates differently to insulin resistance across diverse Asian populations.
Limits
The sample size was small (n = 41) with a substantial ethnic imbalance (31 Chinese vs. 10 Asian Indian individuals), underpowering subgroup analyses for Asian Indians. Specific effect sizes, variances, and p-values are absent from the abstract. Brown adipose tissue and skeletal muscle contributions were not directly measured.
Cited by
- context Mild cold stress naturally lowers the respiratory quotient (RQ), shifting substrate utilization toward fat oxidation.