Preliminary findings from a scoping review and meta-analysis on sex differences in human physiological responses to cold stress

Objective: As global warming increases access to high-latitude regions, trade and military activity in cold environments are expanding, creating a need for better understanding of human cold physiology. Despite growing female participation in these sectors, most thermoregulation research has focused on males. Sex differences in anthropometrics, body composition, and hormones suggest distinct thermoregulatory strategies, but evidence remains inconsistent regarding their magnitude and mechanisms. Hypothesis: Based on existing narrative reviews, we hypothesized that females would have lower skin temperatures, and that males would have higher metabolic rates, but that core temperatures would be equivocal between the sexes. Further, we hypothesized that when standardizing for anthropometric factors (e.g. body surface area-to-mass ratio), the differences in metabolic rates would be eliminated. Methods: This scoping review followed PRISMA-ScR guidelines. Using a PICO-based strategy, two researchers systematically searched Scopus, Academic Search Premier, MEDLINE, and CINAHL to November 4, 2024. Inclusion criteria were: 1) healthy adults aged 18-65 years (excluding menopausal and amenorrheic females, drug- or alcohol-exposed, or clinical populations); 2) direct comparisons between females and males within-manuscript; 3) whole-body cold exposure (air, water, or water-perfused-suit; internal cooling and post-exercise recovery cooling excluded); and 4) at least one physiological response to cold stress. Data were extracted in duplicate for anthropometric, physiological, and perceptual outcomes. Variables reported in ≥5 studies were meta-analyzed using Hedges’ g and 95% confidence intervals. Results: From the 12,753 articles screened, 44 studies (publication dates: 1978–2024; 32 passive, 12 involving exercise) met inclusion criteria (1,162 participants; 610 males, 552 females). Across all studies, 96 distinct outcome variables were reported, with skin temperature (n=31), metabolic rate (n=26), and rectal temperature (n=21) being the most measured variables. Males were taller, heavier, had greater body surface area (BSA), and lower BSA-to-mass ratios than females (all p< 0.001). From preliminary analyses, fifteen passive cold-exposure studies with both metabolic and anthropometric data (459 participants, 44.9% female) were pooled. For a given cold exposure, males showed higher absolute metabolic heat production (g=0.50 [0.31, 0.70]) and higher values scaled to BSA (g=0.26 [0.07, 0.45]) and BSA/mass ratio (g=0.59 [0.40, 0.79]), but no difference when expressed per kilogram body mass (g=0.11 [-0.07, 0.30]). Males experienced larger core temperature reductions (g=-0.45 [-0.68, -0.23]), with no clear sex difference in skin temperature (g=0.14 [-0.03, 0.32]). Conclusion: Preliminary meta-analytic findings challenge several commonly cited sex differences in cold physiology. Specifically, contrary to our initial hypotheses, core temperature seems to reduce more rapidly in males, skin temperatures appear to be similar between the sexes, and higher metabolic rates in males cannot solely be attributed to body morphology, especially to BSA-to-mass ratio. However, heterogeneity in protocols and reporting currently limits firm conclusions. Funding: This project was not funded. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.