Sagittal Abdominal Diameter Measured Visceral Obesity in American Adults

Background/Purpose: Sagittal abdominal diameter (SAD) is a simple measure of visceral obesity and has been recently added to the National Health and Nutrition Examination Survey (NHANES) to provide population-based reference data for obesity-related health risk assessments. The purposes of this study were (a) to describe sagittal abdominal diameter assessed visceral obesity in American adults across demographical characteristics, and (b) to examine the independent relationship between visceral obesity and self-reported physical activity.

Method: A total of 5218 adults (2620 males, 2598 females) aged 20 years and older completed the 2011-2012 NHANES’ anthropometric measurements, demographics and physical activity questionnaires. Their data were included in the study.

Analysis/Results: SAS survey procedures were used for data analysis. The average SAD score among the American adults was 22.51cm. About 54% of adults were viscerally obese (SAD>=22 cm for male, SAD>=20 cm for female). There was no gender difference in the percentage of adults being viscerally obese (53.58% of males vs. 55.12% of females, p=0.16). However, more non-Hispanic Blacks (63.88%) were viscerally obese compared with non-Hispanic Whites (54.29%, p<0.0001), Hispanics (57.79%, p=0.007), and non-Hispanic Asians (26.35%, p<0.0001), whereas non-Hispanic Asians had the lowest visceral obesity rate compared with other race/ethnicity groups, p<0.0001. Visceral obesity rate increased with age, with 41.22% of younger adults (20-39 yrs) being viscerally obese compared with 62.36% of middle aged adults (40-59 yrs) and 60.24% of older adults (60+ yrs), p<0.0001. Adults with college education or above had lowest visceral obesity prevalence (46.33%) compared with those with less than high school education (59.94%, p<0.0001), high school education (57.83%, p<0.0005), and some college education (57.05%, p<0.0001). There was no difference in the prevalence of visceral obesity between adults with high income (poverty-income-ratio [PIR]>400%; 51.49%), middle income (PIR >=200% but <400%; 55.68%), and low income (PIR<200%; 56.16%). SAD was negatively correlated with moderate-to-vigorous leisure-time physical activity (LTPA) hours (r=-0.15, p<0.0001), and positively associated with sedentary time (r=0.12, p < 0.0001), but had no relationship with total amount of PA participation, transportation PA time, and moderate-to-vigorous workplace PA hours. The prevalence of visceral obesity was higher in adults who reported no moderate-to-vigorous LTPA (61.65%) than those who engaged in moderate-to-vigorous LTPA (48.39%), p<0.0001.

Conclusions: More than half of American adults are viscerally obese when assessed by SAD. The prevalence of visceral obesity varies across race/ethnicity, age group, and education. Low participation in moderate-to-vigorous LTPA is associated with large SAD scores and high visceral obesity rates.