Survey of the Relationship Between Obesity Prevalence and Ambient Temperature: A Systematic Review

Introduction: Ambient temperature is considered as a factor affecting on the body's metabolism, So that increase or decrease ambient temperature to the range thermoneutral zone (TNZ) (This temperature is 20.3°C to 23°C for covered people) lead to body metabolic changes, and maybe effective on the increase or reduce the prevalence of obesity. Our aim of this study was to review the relationship between ambient temperature and obesity in different areas of the ambient temperature. Methods: We conducted a complete search up to July 2019 in PubMed, and SCOPUS through a search strategy that included three terms to describe the exposure, and four-term for the outcome. The quality was assessed by the Newcastle–Ottawa Quality Assessment. Among 461 studies selected, Finally 4 cross–section were included in our systematic review. The quality of four studies was 9 on a 9-point scale. The four cross-section studies were reported correlation between the prevalence of obesity and ambient temperatures in different regions of four countries Spain, Korea, England, and the US. Results: There was an association between ambient temperature and obesity in different areas of the ambient temperature. Thus, by increasing the ambient temperature to the TNZ (This temperature is 20.3°C to 23°C for covered people) range the prevalence of obesity increases and with increasing temperature above the TNZ range the prevalence of obesity decreases.  Conclusion: Findings from available data suggested, the ambient temperature may affect the prevalence of obesity, but to determine the relationship between ambient temperature and the prevalence of obesity, further studies are needed in different countries in a wider temperature range.