Obesity continues to be a public health concern across the globe. Obesity has a demonstrated association with health behaviors and health outcomes, such as diabetes, hypertension, and cancer. Over the past 2 decades, obesity has increased worldwide and remains highest in the United States. It is critical to understand the definition of obesity, using body mass index appropriately, recent estimates, and risk factors as a framework within which clinicians should work to help reduce the burden of obesity. This framework, including the Healthy People 2020 place-based approach to social determinants of health, is described in this article.
Key points
- •
Trends in obesity prevalence over the past 2 decades have increased across the globe while remaining high in the United States.
- •
Obesity, for screening purposes, is defined as a body mass index (BMI) greater than or equal to 30 kg/m 2 for adults and BMI above the age- and sex-specific 95th percentile of the Centers for Disease Control and Prevention or World Health Organization growth charts.
- •
Obesity is higher among women, racial/ethnic groups, and at lower levels of education and income.
- •
Data collection of ethnic subgroups across all races will improve the ability to monitor trends in obesity and potential other health outcomes over time.
- •
It is critical to consider both individual behaviors and social determinants of health for identifying at-risk populations to develop evidence-based, culturally relevant clinical and population interventions.
Introduction
Obesity continues to be a public health concern across the globe. Obesity has a demonstrated association with health behaviors and health outcomes, such as diabetes, hypertension, and cancer. Over the past 2 decades, obesity has increased worldwide and remains highest in the United States. It is critical to understand the definition of obesity, using body mass index (BMI) appropriately, recent estimates, and risk factors as a framework within which clinicians should work to help reduce the burden of obesity and obesity-related health outcomes. This framework, including the Healthy People 2020 place-based approach to social determinants of health, is described in this article.
Introduction
Obesity continues to be a public health concern across the globe. Obesity has a demonstrated association with health behaviors and health outcomes, such as diabetes, hypertension, and cancer. Over the past 2 decades, obesity has increased worldwide and remains highest in the United States. It is critical to understand the definition of obesity, using body mass index (BMI) appropriately, recent estimates, and risk factors as a framework within which clinicians should work to help reduce the burden of obesity and obesity-related health outcomes. This framework, including the Healthy People 2020 place-based approach to social determinants of health, is described in this article.
Definition and measurement
BMI is the most common measure used for population and clinical screening for obesity. Weight and height are needed for BMI and usually determined using measured weight and height in clinical settings and self-reported weight and height in larger population health studies. BMI is calculated as one’s weight in kilograms divided by one’s height in meters squared (kg/m 2 ). Although the definition of obesity is dependent on the method used to determine the presence of obesity (ie, BMI, waist circumference), for the purpose of this article, obesity is defined based on the World Health Organization’s international adult classification of BMI ( Table 1 ).
| Classification | BMI (kg/m 2 ) | |
|---|---|---|
| Principal Cutoff Points | Additional Cutoff Points | |
| Underweight | <18.50 | <18.50 |
| Severe thinness | <16.00 | <16.00 |
| Moderate thinness | 16.00–16.99 | 16.00–16.99 |
| Mild thinness | 17.00–18.49 | 17.00–18.49 |
| Normal range | 18.50–24.99 | 18.50–22.99 |
| 23.00–24.99 | ||
| Overweight | ≥25.00 | ≥25.00 |
| Preobese | 25.00–29.99 | 25.00–27.49 |
| 27.50–29.99 | ||
| Obese | ≥30.00 | ≥30.00 |
| Obese class I | 30.00–34.99 | 30.00–32.49 |
| 32.50–34.99 | ||
| Obese class II | 35.00–39.99 | 35.00–37.49 |
| 37.50–39.99 | ||
| Obese class III | ≥40.00 | ≥40.00 |
Currently, there is no consensus on an international classification of BMI for children. However, for the purpose of this article, obesity is classified as BMI greater than or equal to the age- and sex-specific 95th percentile based on the 2000 Centers for Disease Control and Prevention growth charts.
Obesity in North America
- •
In the United States, the prevalence of obesity among adults over the age of 20 is approximately 36%.
- •
38.3% of women and 34.3% of men in the United States are obese, and obesity prevalence in the United States varies by gender ( Fig. 1 ), race/ethnicity ( Fig. 2 ), and socioeconomic status.
Fig. 1
Obesity prevalence among adults aged 20 and over, by sex and age: National Health and Nutrition Examination Survey, 2011 to 2014. a Significantly different from those aged 20 to 39. b Significantly different from women of the same age group. NOTE: Totals were age adjusted by the direct method to the 2000 US census population using the age groups 20 to 39, 40 to 59, and 60 and over. Crude estimates are 36.5% for all, 34.5% for men, and 38.5% for women.
( From Ogden CL, Carroll MD, Fryar CD, et al. Prevalence of obesity among adults and youth: United States, 2011–2014. NCHS Data Brief 2015;219.)
Fig. 2
Obesity prevalence among adults aged 20 and over, by sex and race and Hispanic origin: United States, 2011 to 2014. a Significantly different from non-Hispanic Asian persons. b Significantly different from non-Hispanic white persons. c Significantly different from Hispanic persons. d Significantly different from women of the same race and Hispanic origin. NOTE: All estimates are age adjusted by the direct method to the 2000 US census population using the age groups 20 to 39, 40 to 59, and 60 and over.
( From Ogden CL, Carroll MD, Fryar CD, et al. Prevalence of obesity among adults and youth: United States, 2011–2014. NCHS Data Brief 2015;219.)
- •
Canada has lower adult obesity prevalence than the United States across gender ( Fig. 3 ).
Fig. 3
Obesity prevalence among adults aged 20 to 79 years, by sex: Canada, 2007 to 2009 and United States, 2007 to 2008. a Statistically different from estimate for Canada ( P <.05). b Use with caution (coefficient of variation 16.6%–33.3%). NOTE: Estimates were age standardized by the direct method to the 2000 US Census population using age groups 20 to 39, 40 to 59, and 60 to 79. Pregnant women are excluded. Obesity class estimates do not sum to exact totals due to rounding.
( From Shields M, Carroll MD, Ogden CL. Adult obesity prevalence in Canada and the United States. NCHS Data Brief 2011;56.)
- •
Among children, the prevalence of obesity in the United States was 17% in 2011 to 2014, and similar to adults, prevalence also varies by gender, age ( Fig. 4 ), and race/ethnicity ( Fig. 5 ).
