Abstract Body (Do not enter title and authors here):
Background: The US Asian population comprises diverse ethnic subgroups with distinct cultural and dietary profiles that influence their health outcomes. However, most research has focused on obesity trends among general populations, and little is known about trends within Asian ethnic subgroups. We examined the variation in obesity prevalence among the four largest US Asian subgroups in comparison with White, Black, and Hispanic groups across five age decades of the adult lifespan.

Methods: This retrospective study used electronic health record data for 101,837 Filipino, 98,281 Chinese, 76,916 South Asian, 28,764 Vietnamese, 805,051 White, 124,412 Black, and 328,064 Hispanic adults aged 30-79y who were members of a Northern California health plan in 2019 and had a measured BMI. Obesity was defined as body mass index (BMI) ≥27.5 kg/m2 for Filipino, Chinese, South Asian, and Vietnamese adults and ≥30 kg/m2 for White, Black, and Hispanic adults. Obesity prevalence was compared by sex in Asian and non-Asian groups at ages 30-39y through 70-79y.

Results: Among Asian men and women, obesity prevalence was consistently higher among Filipino and South Asian adults than among Chinese and Vietnamese adults (Figure). Obesity prevalence in Asian adults peaked at 58-59% for Filipino men at age 30-49y, 43-44% for Filipino women at 30-49y, and 42-46% for South Asian women at 50-69y. At age ≥40y, obesity prevalence was similar in South Asian and White men, whereas Filipino men tracked higher, in the range of Black and Hispanic men. For women, obesity prevalence was higher among Filipina than South Asian women under age 50y. However, this trend reversed in women age ≥50y, when prevalence was similar among Filipina and White women, and higher for South Asian women who tracked closer to Hispanic women. Black women had the highest obesity prevalence across all age decades.

Conclusion: Across five age decades, obesity prevalence was substantially higher among Filipino and South Asian than Chinese and Vietnamese ethnic groups. These trends point to an alarmingly high obesity burden among Filipino and South Asian adults and underscores the importance of using disaggregated Asian ethnic subgroup data to study health risks and outcomes.