The geographic distribution of obesity in the US and the potential regional differences in misreporting of obesity

Abstract

Objective: State-level estimates of obesity based on self-reported height and weight suggest a geographic pattern of greater obesity in the Southeastern US; however, the reliability of the ranking among these estimates assumes errors in self-reporting of height and weight are unrelated to geographic region.

Design and methods: Regional and state-level prevalence of obesity (body mass index ≥ 30 kg m(-2) ) for non-Hispanic black and white participants aged 45 and over were estimated from multiple sources: self-reported from the behavioral risk factor surveillance system (BRFSS 2003-2006) (n = 677,425), self-reported and direct measures from the National Health and Nutrition Examination Study (NHANES 2003-2008) (n = 6,615 and 6,138, respectively), and direct measures from the REasons for Geographic and Racial Differences in Stroke (REGARDS 2003-2007) study (n = 30,239).

Results: Data from BRFSS suggest that the highest prevalence of obesity is in the East South Central Census division; however, direct measures suggest higher prevalence in the West North Central and East North Central Census divisions. The regions relative ranking of obesity prevalence differs substantially between self-reported and directly measured height and weight.

Conclusions: Geographic patterns in the prevalence of obesity based on self-reported height and weight may be misleading, and have implications for current policy proposals.

Figure 1

BRFSS data showing the percent of population that is obese (≥30 kg/m²) at the state level: 1994, 2002 and 2010.

Figure 2

US census regions and divisions.

Figure 3

State ranking for age-sex adjusted prevalence of obesity (with % obese), listed from the most obese to least obese by BRFSS and REGARDS. For example, based on BRFSS Mississippi had the highest proportion of residents with obesity with 30.5%; however, based on REGARDS the proportion of obesity in Mississippi was 4^th highest with 38.7%. States with similar rankings in the two studies will have relatively flat lines (e.g., Louisiana, which is third in both studies), while states with discordant rankings will have lines with steep slopes (e.g., Missouri, which is 17^th in BRFSS and 1^st in REGARDS). Data shown for all states with at least 200 REGARDS participants.

Figure 4

Comparisons of obesity prevalence estimates for Non-Hispanic black and white adults over 45 years of age from three national datasets (NHANES-measured, BRFSS, and REGARDS) among the Census divisions of the United States. Data are shown for the estimated prevalence (point) and 95% confidence interval by each study (line on either side, or above and below, each estimate). Abbreviations: MA=Middle Atlantic, ENC=East North Central, WNC=West North Central, SA=South Atlantic, ESC=East South Central, WSC=West South Central, M=Mountain, and P=Pacific (NHANES sample size not sufficient for estimation in NE=New England)