Associations between extreme temperature events and daily step counts by weight status and modifying effects of sociodemographic factors: a longitudinal study.
Lin Z, Li Y, et al. • The American journal of clinical nutrition • 2026
Extreme weather events significantly reduced daily step counts, with heatwaves disproportionately affecting individuals with overweight and cold spells disproportionately affecting individuals with normal weight, and high income consistently attenuated these disparities.
Key Findings
Results
Heatwaves were associated with a significantly larger reduction in daily step counts among individuals with overweight compared to those with normal weight.
Overweight individuals experienced a reduction of -959.68 steps (95% CI: -1198.13, -721.22) during heatwaves.
Normal weight individuals experienced a smaller reduction of -331.16 steps (95% CI: -625.50, -36.83) during heatwaves.
The difference in reduction between overweight and normal weight groups was statistically significant.
The study was conducted in Henan Province, China, using a longitudinal panel design.
Results
Cold spells were associated with a disproportionately larger reduction in daily step counts among participants with normal weight compared to those with overweight.
Normal weight individuals experienced a reduction of -1832.46 steps (95% CI: -2136.15, -1528.76) during cold spells.
Overweight individuals experienced a milder reduction of -1067.66 steps (95% CI: -1317.40, -817.91) during cold spells.
The pattern of vulnerability was reversed between heatwaves and cold spells depending on weight status.
Distributed lag nonlinear models were applied to examine the effects of extreme weather events including their intensity and duration.
Results
High income consistently attenuated the disparities in step count reductions associated with both heatwaves and cold spells across weight status groups.
Interaction analysis revealed that high income modified the associations between extreme weather events and step counts (P-interaction < 0.05).
High income attenuated disparities during both heatwave and cold spell events.
Individuals with low income were identified as having heightened vulnerability to both heatwaves and cold spells.
Income was described as 'consistently' modifying these weather-related effects across weight status groups.
Results
Body weight emerged as a primary modifying factor of the associations between extreme temperature events and daily step counts, with age and sex also modifying these associations.
Interaction analysis examined sociodemographic factors including income, age, and sex.
Body weight was identified as a 'primary factor' among the sociodemographic and anthropometric modifiers examined.
Age and sex also modified the associations between extreme weather events and step counts, though to a lesser degree than body weight.
The study specifically investigated modifying effects to address a recognized research gap in the field.
Results
Extreme weather events significantly reduced daily step counts overall in the study population.
Both heatwaves and cold spells were associated with reductions in step counts.
The study used a longitudinal panel study design in Henan Province, China.
Distributed lag nonlinear models were used to examine associations accounting for lag effects and nonlinearity.
The study examined both the intensity and duration of extreme weather events as part of the exposure characterization.
Results
Individuals with low income or high BMI are associated with heightened vulnerability to heatwaves, whereas individuals with low income or normal BMI are linked to greater sensitivity during cold spells.
The vulnerability profiles for heatwaves and cold spells differ by weight status group.
Low income was a consistent risk factor for greater weather-related reductions in physical activity across both types of extreme temperature events.
High BMI conferred greater heatwave vulnerability while normal BMI conferred greater cold spell vulnerability.
These findings highlight distinct subgroups that may require targeted interventions during different types of extreme weather events.
What This Means
This research suggests that extreme weather events — both heatwaves and cold spells — meaningfully reduce how many steps people take each day, but the impact varies significantly depending on a person's body weight and income level. During heatwaves, people who were overweight saw their daily step counts drop by nearly 960 steps on average, which was a much larger decrease than the roughly 331-step reduction seen in people with normal weight. During cold spells, the pattern reversed: people with normal weight experienced a reduction of over 1,800 steps per day, while overweight individuals saw a smaller decline of about 1,068 steps. These patterns suggest that different groups face different risks depending on the type of extreme weather event.
Income also played an important role. Higher-income individuals were more protected from these weather-related drops in physical activity, regardless of weight status or type of extreme weather event. This suggests that financial resources may help people adapt — for example, by accessing climate-controlled gyms, transportation, or other alternatives when outdoor conditions are unfavorable. Age and sex also influenced how much extreme weather affected physical activity, though weight status was identified as the primary differentiating factor.
This research matters because physical inactivity is linked to numerous health problems, and climate change is making extreme weather events more frequent and severe. Understanding which populations are most vulnerable to weather-related reductions in physical activity could help public health officials design targeted interventions. For instance, people with obesity may need additional support during heatwaves to maintain physical activity levels, while normal-weight individuals — particularly those with lower incomes — may need more support during cold spells.
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Lin Z, Li Y, Shi Y, Li J, Wang Z, Xu J, et al.. (2026). Associations between extreme temperature events and daily step counts by weight status and modifying effects of sociodemographic factors: a longitudinal study.. The American journal of clinical nutrition. https://doi.org/10.1016/j.ajcnut.2026.101312