September 2022

CARDIOVASCULAR

ASIAN AMERICANS’ OBESITY PREVALENCE IS NOT ONE-SIZE-FITS-ALL

Featuring: Nilay Shah, MD, MPH

First study to look at obesity based on Asian American subgroups​

Asian Americans, the fastest-growing racial/ethnic group in the United States, cannot be lumped into one uniform group when looking at obesity prevalence.

A new Northwestern Medicine study published in the Annals of Internal Medicine reports significant variation in the prevalence of obesity among subgroups of Asian American adults. Health risks in this population also may start at a lower BMI than standard BMI definitions of obesity.

Using criteria specific to Asian populations (defined as a BMI or body mass index greater than 27.5), the prevalence of obesity ranged from 13 percent in Chinese American adults to 29 percent in Filipino American adults, the study found.

“Clinicians must be aware that the cardiovascular and metabolic risks related to obesity may be different among individuals who belong to different Asian subgroups,” said lead author Nilay Shah, MD, MPH, assistant professor of Medicine in the Division of Cardiology and a Northwestern Medicine physician.

​​“The standard approach and definitions of obesity based on specific body mass index thresholds may not be appropriate for the Asian American population,” Shah said.

Applying standard definitions to Asian Americans may miss a large portion of adults from these groups who have higher risks for disease because of their body composition, the study found.

The Asian American population is expected to number more than 46 million by 2060. Until recently, the health of this population was not well described because individuals were grouped into a single ‘Asian,’ category, Shah said, which does not appropriately represent the different subpopulations of Asian American individuals.

“Our study addresses the two major prevailing limitations in understanding obesity prevalence in Asian American populations,” Shah said. “First, we identify the prevalence of obesity in the six largest Asian American subgroups: Asian Indian, Chinese, Filipino, Japanese, Korean and Vietnamese, which better represents the variability in obesity in Asian subgroups in the U.S.”

​“Additionally,” Shah explained, “We evaluate the prevalence of obesity based on both standard BMI thresholds that are currently applied to all adults, and further identify the prevalence of obesity based on lower BMI thresholds that may be more appropriate for Asian individuals, as suggested by the World Health Organization.”

“The standard threshold for obesity is a BMI of 30 or above,” Shah said. “Recent work from our group and others suggests that number should be a BMI of 27.5 or above for Asian American people, based on their health risks.”

The consequence of these findings is that clinicians with Asian American patients may need to screen them for diabetes, cholesterol and hypertension at lower BMI levels than they otherwise normally would for patients of other race/ethnicity groups. Otherwise, they may be missing obesity-related health risks in their Asian American patients, Shah said.

​Investigators used data from the Behavioral Risk Factor Surveillance System, an annual state-based survey of adults in the United States between 2013-2020, to calculate the prevalence of obesity across racial and ethnic groups including Asian American subgroups.

“The next step in research is to understand the optimal BMI thresholds to define obesity for Asian American individuals,” Shah said. “Knowing these optimal thresholds would guide clinical management of obesity and its associated metabolic and cardiovascular risks for these groups.”

Other Northwestern authors include Namratha Kandula, MD, MPH, professor of Medicine in the Division of General Internal Medicine; and Sadiya Khan, MD, MSc, assistant professor of Medicine in the Division of Cardiology.

This research was funded in part by grant K23HL157766 from the National Heart, Lung, and Blood Institute of the National Institutes of Health.

​​This article was originally published in the Feinberg School of Medicine News Center on October 11, 2022.
Nilay Shah, MD, MPH, assistant professor of Medicine in the Division of Cardiology and a Northwestern Medicine physician.

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