Abstract
This study uses NHANES data to assess trends in obesity and severe obesity stratified by race and Hispanic origin among US residents from 1999 to 2018.
Public health surveillance of obesity describes changes over time and identifies subgroups at risk of obesity-related consequences. We analyzed trends, stratified by race and Hispanic origin, in high weight for length, obesity, and severe obesity in the US from 1999 to 2018.
Methods
Data from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional survey of the civilian noninstitutionalized US population, were used. Participants older than 17 years provided consent; for those younger than 18 years, parental permission was obtained, and documented assent was obtained for 7 through 17 years. NHANES was approved by the National Center for Health Statistics (NCHS) Research Ethics Review Board. The response rate was 76.0% during 1999-2000 and declined to 48.8% during 2017-2018.1 During the physical examination, standardized measurements of weight, length, and height were conducted.
Among children younger than 24 months, high weight for length was defined as weight for length at or above the 97.7th percentile of the World Health Organization growth standards.2 Among children and adolescents between 2 and 19 years, obesity was defined as body mass index (BMI) for age at or above the 95th percentile, and severe obesity was defined as BMI for age 120% of the 95th percentile or higher on the CDC growth charts.3 Adult obesity and severe obesity were BMI of 30 or higher and 40 or higher, respectively.
Linear and quadratic trends were evaluated in regression models that treated 2-year cycles as continuous. Joinpoint software was used to assess changes in slopes. Differences in slope between race and Hispanic-origin groups were tested, and Satterthwaite-adjusted F statistic P values were reported. Trends were stratified by age (children and adolescents) and sex (adults) because of significant 3-way interactions. Although trends using 2-year cycles are more efficient than using 4-year pooled estimates,4 the 2-year estimates for youth were not reliable, so pooled 4-year estimates were shown.
Examination sample weights were used to adjust for oversampling, nonresponse, and noncoverage. Prevalence estimates were evaluated using NCHS presentation standards.5 Estimates for adults were age adjusted to the projected 2000 census population. A 2-sided P < .05 determined statistical significance. SAS version 9.4 (SAS Institute Inc) and SUDAAN version 11.0 (RTI International) were used for analyses.
Results
The analytic sample included 92 759 nonpregnant persons with measured weight and length or height.
Among children younger than 6 years, there were no significant trends from 1999 through 2018 in high weight for length for birth to 24 months or obesity for those 2 through 5 years (Table). Among non-Hispanic Black children 2 through 5 years, obesity increased from 1999-2000 to 2005-2006 and then did not change significantly. For children 6 through 11 years, obesity increased overall from 15.8% (95% CI, 13.6%-18.3%) to 19.3% (95% CI, 16.9%-22.0%), but there were no significant trends in any race and Hispanic-origin subgroup. Among adolescents 12 through 19 years, obesity increased from 16.0% (95% CI, 14.5%-17.6%) to 20.9% (95% CI, 18.5%-23.5%) and severe obesity from 5.3% (95% CI, 4.4%-6.4%) to 7.6% (95% CI, 6.1%-9.4%). Similarly, obesity and severe obesity increased among Mexican American adolescents. Obesity also increased significantly in non-Hispanic Black adolescents.
Table. Prevalence of High Weight for Recumbent Length, Obesity, and Severe Obesity, Birth to 19 Years, by Race and Hispanic Origin: US, 1999-2000 to 2017-2018a.
| Survey years | All, % (95% CI)b | Non-Hispanic White, % (95% CI) | Non-Hispanic Black, % (95% CI) | Mexican American, % (95% CI) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. | High weight for length or obesity | Severe obesity | No. | High weight for length or obesity | Severe obesity | No. | High weight for length or obesity | Severe obesity | No. | High weight for length or obesity | Severe obesity | |
| Birth to 23 mo | ||||||||||||
| 1999-2002 | 1338 | 8.5 (6.8-10.4) | 400 | 5.7 (3.7-8.5) | 258 | 11.8 (7.8-16.9) | 510 | 13.0 (9.9-16.5) | ||||
| 2003-2006 | 1588 | 7.8 (6.2-9.6) | 488 | 6.8 (4.7-9.4) | 357 | 7.5 (4.8-11.2) | 579 | 9.6 (7.0-12.7) | ||||
| 2007-2010 | 1422 | 8.7 (7.1-10.5) | 474 | 8.1 (5.5-11.5) | 230 | 7.6 (4.3-12.2) | 463 | 11.7 (8.5-15.6) | ||||
| 2011-2014 | 1193 | 7.6 (6.0-9.6) | 347 | 6.5 (4.1-9.6) | 268 | 9.2 (5.7-13.9) | 273 | 9.7 (5.7-15.3) | ||||
| 2015-2018 | 1165 | 9.2 (7.1-11.8) | 418 | 8.8 (5.8-12.8) | 218 | 10.2 (5.5-17.0) | 248 | 11.3 (5.9-19.1) | ||||
| P valuec | .73 | .30 | .81 | .79 | ||||||||
| Biennial change | 0.1 (−0.3-0.4) | 0.2 (−0.2-0.6) | −0.1 (−0.8-0.6) | −0.1 (−0.8-0.6) | ||||||||
| 2-5 y | ||||||||||||
| 1999-2002 | 1521 | 10.3 (8.0-13.1) | 2.2 (1.2-3.9) | 450 | 8.7 (5.8-12.3) | 2.0 (0.8-4.4)d | 439 | 8.8 (6.0-12.4) | 2.5 (1.2-4.7) | 469 | 13.1 (9.2-17.9) | 2.5 (1.0-5.1) |
| 2003-2006 | 1771 | 12.3 (10.4-14.4) | 2.2 (1.4-3.2) | 498 | 10.6 (7.6-14.1) | 1.4 (0.5-3.4)d | 517 | 14.8 (11.8-18.1) | 3.1 (1.6-5.4) | 558 | 16.7 (12.1-22.1) | 3.7 (2.1-6.1) |
| 2007-2010 | 1756 | 11.1 (9.4-12.9) | 2.2 (1.4-3.3) | 618 | 9.0 (6.6-11.9) | 1.8 (0.6-4.2) | 344 | 15.0 (10.9-19.9) | 3.1 (1.5-5.5) | 471 | 14.6 (11.5-18.1) | 3.1 (1.7-5.1) |
| 2011-2014 | 1714 | 8.9 (7.1-11.0) | 1.7 (1.0-2.7) | 390 | 5.2 (3.1-8.3) | 1.0 (0.2-2.9)d | 485 | 10.4 (7.5-14.0) | 2.1 (0.7-4.8)d | 349 | 15.3 (11.3-20.1) | 2.9 (0.8-7.0)e |
| 2015-2018 | 1491 | 13.7 (12.0-15.5) | 2.2 (1.4-3.5) | 481 | 12.4 (9.6-15.7) | 0.9 (0.1-3.1)d | 361 | 12.5 (8.0-18.4) | 2.7 (0.7-7.2)d,e | 250 | 17.3 (11.8-24.0) | 4.1 (1.8-7.9)e |
| P valuec | .39 | .94 | .69 | .30 | f | .96 | .41 | .67 | ||||
| Biennial change | 0.1 (−0.2-0.5) | 0.0 (−0.2-0.2) | 0.1 (−0.4-0.5) | −0.1 (−0.3-0.1) | f | 0.0 (−0.3-0.3) | 0.3 (−0.5-1.1) | 0.1 (−0.3-0.4) | ||||
| 6-11 y | ||||||||||||
| 1999-2002 | 2213 | 15.8 (13.6-18.3) | 4.8 (3.6-6.2) | 575 | 13.6 (10.5-17.1) | 3.8 (2.3-6.0) | 714 | 19.6 (16.8-22.8) | 6.4 (4.7-8.4) | 745 | 21.8 (18.3-25.7) | 6.2 (4.3-8.5) |
| 2003-2006 | 2096 | 17.0 (14.5-19.7) | 4.6 (3.7-5.6) | 558 | 15.0 (11.2-19.4) | 2.5 (1.3-4.1) | 673 | 21.3 (17.7-25.3) | 8.8 (6.7-11.2) | 671 | 23.7 (19.8-28.1) | 10.4 (7.5-14.0) |
| 2007-2010 | 2410 | 18.8 (17.3-20.4) | 5.4 (4.4-6.5) | 747 | 16.4 (13.9-19.3) | 4.0 (2.7-5.7) | 552 | 23.9 (19.5-28.8) | 8.1 (6.0-10.7) | 675 | 23.3 (20.1-26.8) | 8.6 (5.8-12.0) |
| 2011-2014 | 2562 | 17.5 (15.2-20.1) | 5.6 (4.5-6.9) | 638 | 13.6 (9.8-18.3) | 3.4 (1.6-6.4) | 714 | 21.4 (17.5-25.8) | 8.8 (6.5-11.6) | 537 | 25.3 (21.6-29.2) | 9.2 (6.9-12.0) |
| 2015-2018 | 2292 | 19.3 (16.9-22.0) | 5.8 (4.4-7.4) | 645 | 15.5 (12.4-19.1) | 4.4 (2.7-6.8) | 516 | 22.7 (18.4-27.5) | 8.3 (5.9-11.2) | 471 | 28.2 (23.3-33.4) | 8.9 (6.4-12.0) |
| P valuec | .04 | .11 | .57 | .35 | .20 | .22 | .05 | .33 | ||||
| Biennial change | 0.4 (0.0-0.7) | 0.2 (0.0-0.4) | 0.1 (−0.4-0.6) | 0.1 (−0.1-0.4) | 0.4 (−0.2-0.9) | 0.2 (−0.1-0.5) | 0.7 (0.0-1.3) | 0.2 (−0.2 to 0.5) | ||||
| 12-19 y | ||||||||||||
| 1999-2002 | 4566 | 16.0 (14.5-17.6) | 5.3 (4.4-6.4) | 1143 | 13.7 (11.4-16.2) | 4.1 (2.9-5.5) | 1316 | 21.1 (18.7-23.6) | 8.6 (6.6-10.9) | 1704 | 22.3 (19.7-25.1) | 7.6 (6.1-9.2) |
| 2003-2006 | 4301 | 17.6 (15.1-20.3) | 6.3 (5.0-7.8) | 1139 | 16.0 (12.7-19.7) | 5.5 (4.0-7.3) | 1506 | 22.9 (20.6-25.3) | 11.0 (9.0-13.2) | 1354 | 21.1 (18.3-24.0) | 6.6 (5.1-8.3) |
| 2007-2010 | 2491 | 18.2 (16.1-20.5) | 6.7 (5.0-8.7) | 808 | 15.9 (12.6-19.6) | 5.2 (2.9-8.4) | 602 | 24.1 (20.7-27.7) | 11.9 (9.1-15.1) | 630 | 23.1 (18.9-27.7) | 8.7 (6.4-11.5) |
| 2011-2014 | 2602 | 20.5 (17.8-23.5) | 7.8 (6.3-9.6) | 619 | 19.6 (14.7-25.3) | 6.7 (4.6-9.2) | 711 | 22.6 (18.0-27.8) | 11.6 (8.5-15.4) | 539 | 23.5 (19.6-27.6) | 10.0 (7.6-12.9) |
| 2015-2018 | 2381 | 20.9 (18.5-23.5) | 7.6 (6.1-9.4) | 682 | 15.9 (13.1-19.0) | 4.9 (3.4-6.8) | 539 | 28.2 (23.6-33.3) | 13.0 (9.2-17.7) | 479 | 30.6 (24.8-36.9) | 12.9 (9.2-17.5) |
| P valuec | <.001 | .001 | .06 | .13 | .02 | .05 | .005 | .003 | ||||
| Biennial change | 0.7 (0.3-1.0) | 0.3 (0.1-0.5) | 0.4 (0.0-0.9) | 0.2 (−0.1-0.4) | 0.7 (0.1-1.2) | 0.5 (0.0-0.9) | 1.1 (0.3-1.8) | 0.7 (0.3 to 1.2) | ||||
Data are from the National Health and Nutrition Examination Survey; all estimates except sample sizes are weighted.
Includes self-reported race; Hispanic-origin groups not shown separately.
The linear trends were conducted using 2-year cycles.
Number of individuals with obesity or severe obesity was fewer than 10.
Estimate potentially unreliable; CI width more than 5% and relative CI width more than 130%.
Increased from 1999-2000 to 2005-2006 (slope, 2.4; 95% CI, CI 07-4.2; P = .007); level after 2005-2006 (slope, −0.7; 95% CI −1.6-0.2; P = .13); slope difference, P = .01.
Among men, obesity increased overall from 27.5% (95% CI, 24.3%-30.8%) to 43.0% (95% CI, 37.6%-48.6%) and severe obesity increased from 3.1% (95% CI, 1.9%-4.7%) to 6.9% (95% CI, 5.1%-9.1%). Similarly, obesity and severe obesity increased in all subgroups except non-Hispanic Black men, who did not show a significant increase in obesity after 2005-2006 (Figure). There was a greater increase in obesity among Mexican American men than non-Hispanic White men (3.0 [95% CI, 2.4-3.6] vs 1.4 [95% CI, 0.9-1.9] percentage points biennially; P < .001). Among women overall, obesity increased from 33.4% (95% CI, 29.8%-37.1%) to 41.9% (95% CI, 37.8%-46.1%) and severe obesity from 6.2% (95% CI, 5.0%-7.7%) to 11.5% (95% CI, 8.9%-14.5%) as it did among non-Hispanic White and non-Hispanic Black women. Among Mexican American women, obesity increased while severe obesity increased only after 2009-2010.
Figure. Age-Adjusted Prevalence of Obesity and Severe Obesity in US Adultsa.
aNational Health and Nutrition Examination Survey data, prevalence estimates are weighted and age-adjusted to the projected 2000 Census population using age groups 20-39, 40-59, and 60 or older. Some estimates are potentially unreliable, due to CI width of more than 5% and relative CI width of more than 130% (severe obesity, non-Hispanic White men 2011-2012; severe obesity, Mexican American men 2001-2002, 2017-2018, and women 2001-2002) or due to fewer than 10 individuals with severe obesity (Mexican American men 2003-2004). The estimate for severe obesity in Mexican American men 2003-2004 was potentially unreliable due to the number of individuals with severe obesity being fewer than 10. Sample size ranges are non-Hispanic White men 879-1395; non-Hispanic Black men 374-662; Mexican American men 266-538; non-Hispanic White women 860-1447; non-Hispanic Black women 422-702; and Mexican American women 237-567. Significant linear trends (P < .001) for all groups except for (1) obesity among non-Hispanic Black men, which increased from 1999-2000 to 2005-2006 (slope, 3.4; 95% CI, 1.8-5.0; P < .001) and then leveled after 2005-2006 (slope, 0.3; 95% CI, −0.6 to 1.2; P = .46; difference in slopes, P = .007); (2) severe obesity among non-Hispanic Black women (P = .02); and (3) severe obesity among Mexican American women, which was level 1999-2000 to 2009-2010 (slope, 0.1; 95% CI, −0.5 to 0.6; P = .81) and increased after 2009-2010 (slope, 2.1; 95% CI, 1.1-3.1; P < .001; difference in slopes, P = .004).
Discussion
Between 1999-2000 and 2017-2018, there were no significant trends in high weight for length or obesity among children younger than 6 years. Overall, obesity increased among adolescents, driven primarily by increases in non-Hispanic Black and Mexican American youth. Obesity and severe obesity increased among adult men and women, with no change in obesity among non-Hispanic Black men after 2005-2006 and a more rapid increase in Mexican American than in non-Hispanic White men.
This study has limitations. NHANES response rates have declined; however, an investigation of bias in 2017-2018 data that included comparisons with external data, studying sample and respondent set variation, and comparison of alternative postsurvey adjustments showed that errors in representation from sample variation and nonresponse were minimized with weighting adjustments.6
Section Editor: Jody W. Zylke, MD, Deputy Editor.
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