Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19·2 million participants

Abstract

Background: Underweight and severe and morbid obesity are associated with highly elevated risks of adverse health outcomes. We estimated trends in mean body-mass index (BMI), which characterises its population distribution, and in the prevalences of a complete set of BMI categories for adults in all countries.

Methods: We analysed, with use of a consistent protocol, population-based studies that had measured height and weight in adults aged 18 years and older. We applied a Bayesian hierarchical model to these data to estimate trends from 1975 to 2014 in mean BMI and in the prevalences of BMI categories (<18·5 kg/m(2) [underweight], 18·5 kg/m(2) to <20 kg/m(2), 20 kg/m(2) to <25 kg/m(2), 25 kg/m(2) to <30 kg/m(2), 30 kg/m(2) to <35 kg/m(2), 35 kg/m(2) to <40 kg/m(2), ≥40 kg/m(2) [morbid obesity]), by sex in 200 countries and territories, organised in 21 regions. We calculated the posterior probability of meeting the target of halting by 2025 the rise in obesity at its 2010 levels, if post-2000 trends continue.

Findings: We used 1698 population-based data sources, with more than 19·2 million adult participants (9·9 million men and 9·3 million women) in 186 of 200 countries for which estimates were made. Global age-standardised mean BMI increased from 21·7 kg/m(2) (95% credible interval 21·3-22·1) in 1975 to 24·2 kg/m(2) (24·0-24·4) in 2014 in men, and from 22·1 kg/m(2) (21·7-22·5) in 1975 to 24·4 kg/m(2) (24·2-24·6) in 2014 in women. Regional mean BMIs in 2014 for men ranged from 21·4 kg/m(2) in central Africa and south Asia to 29·2 kg/m(2) (28·6-29·8) in Polynesia and Micronesia; for women the range was from 21·8 kg/m(2) (21·4-22·3) in south Asia to 32·2 kg/m(2) (31·5-32·8) in Polynesia and Micronesia. Over these four decades, age-standardised global prevalence of underweight decreased from 13·8% (10·5-17·4) to 8·8% (7·4-10·3) in men and from 14·6% (11·6-17·9) to 9·7% (8·3-11·1) in women. South Asia had the highest prevalence of underweight in 2014, 23·4% (17·8-29·2) in men and 24·0% (18·9-29·3) in women. Age-standardised prevalence of obesity increased from 3·2% (2·4-4·1) in 1975 to 10·8% (9·7-12·0) in 2014 in men, and from 6·4% (5·1-7·8) to 14·9% (13·6-16·1) in women. 2·3% (2·0-2·7) of the world's men and 5·0% (4·4-5·6) of women were severely obese (ie, have BMI ≥35 kg/m(2)). Globally, prevalence of morbid obesity was 0·64% (0·46-0·86) in men and 1·6% (1·3-1·9) in women.

Interpretation: If post-2000 trends continue, the probability of meeting the global obesity target is virtually zero. Rather, if these trends continue, by 2025, global obesity prevalence will reach 18% in men and surpass 21% in women; severe obesity will surpass 6% in men and 9% in women. Nonetheless, underweight remains prevalent in the world's poorest regions, especially in south Asia.

Funding: Wellcome Trust, Grand Challenges Canada.

Conflict of interest statement

Declaration of interests

JJM reports funding from Medtronics Foundation, outside the submitted work. All other authors declare no competing interests.

Copyright © 2016 NCD Risk Factor Collaboration. Open Access article distributed under the terms of CC BY. Published by Elsevier Ltd.. All rights reserved.

Figures

Figure 1. Trends in age-standardised mean BMI by sex and region

Lighter colours are 95% credible intervals. See appendix (pp 155–355) for results by sex and country. BMI=body-mass index.

figure 2. Age-standardised mean BMI in men by country in 1975 and 2014

See appendix (pp 56–64) for numerical results. BMI=body-mass index.

figure 3. Age-standardised mean BMI in women by country in 1975 and 2014

See appendix (pp 56–64) for numerical results. BMI=body-mass index.

Figure 4. Comparison of mean change in age-standardised mean BMI before and after the year 2000

Each point represents one country. (A) countries in which mean BMI increased more rapidly after 2000 than it had before 2000. (B) countries in which mean BMI increased more slowly after 2000 than it had before 2000. (C) countries in which mean BMI increased before 2000 but decreased after 2000. (D) countries in which mean BMI decreased more rapidly after 2000 than it had before 2000. (E) countries in which mean BMI decreased more slowly after 2000 than it had before 2000. (F) countries in which BMI decreased before 2000 but increased after 2000. BMI=body-mass index.

Figure 5. Trends in age-standardised prevalence of BMI categories in men by region

See appendix (pp 155–355) for results by country. BMI=body-mass index.

Figure 6. Trends in age-standardised prevalence of BMI categories in women by region

See appendix (pp 155–355) for results by country. BMI=body-mass index.

Figure 7. Age-standardised prevalence of underweight, obesity, and severe obesity by sex and country in 2014

Underweight (BMI 2); obesity (BMI ≥30 kg/m2); and severe obesity (BMI ≥35 kg/m2). See appendix (pp 65–107) for numerical results for all BMI ranges. BMI=body-mass index.

Figure 8. Trends in the number of obese and severely obese people by region

A person is obese if they have a body-mass index (BMI) of 30 kg/m2 or higher, or is severely obese if they have a BMI of 35 kg/m2 or higher.

Figure 9. Ten countries with the largest number of underweight, obese, and severely obese men and women in 1975 and 2014

Colours for each country indicate its region, using the same colour scheme as in figure 4. Underweight (BMI 2); obesity (BMI ≥30 kg/m2); and severe obesity (BMI ≥35 kg/m2). BMI=body-mass index.