Obesity in the United States

Two reports published in the Journal of the American Medical Association by Flegal et al and Ogden et al find that 35% of men and 40% of women and 17% of children and teens were obese as of 2014. The corresponding values for class 3-obesity (morbid) were 5.5% for men, 9.9% for women and 6% for children and teens.

The authors obtained their data from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional, nationally representative health examination survey of the US population that includes measured weight and height.

Obesity in adults was defined when the BMI (body mass index) was ≥30 and class 3 obesity when the BMI was ≥40.

This report is based on data from 2638 adult men (mean age, 46.8 years) and 2817 women (mean age, 48.4 years) from the most recent 2 years (2013-2014) of NHANES and data from 21 013 participants in previous NHANES surveys from 2005 through 2012.

Measurements from 40 780 children and adolescents (mean age, 11.0 years; 48.8% female) between 1988-1994 and 2013-2014 were also analyzed.

Obesity in children was defined as a body mass index (BMI) at or above the sex-specific 95th percentile on the US Centers for Disease Control and Prevention (CDC) BMI-for-age growth charts. Extreme obesity was defined as a BMI at or above 120% of the sex-specific 95th percentile on the CDC BMI-for-age growth charts. Detailed estimates were presented for 2011-2014. Trend analyses between 2005-2006 and 2013-2014 also were conducted.

For women, the prevalence of overall obesity and of class 3 obesity showed significant linear trends for increase between 2005 and 2014; there were no significant trends for men.

The odds of being obese fluctuated with age. The researchers found that 41% of adults in their 40s and 50s were obese, compared with 34% of adults in their 20s and 30s and 39% of adults ages 60 and older.

There were also differences based on race and ethnicity. At one end of the spectrum were Asian Americans, 13% of who were obese. At the other end were African Americans, 48% of whom were obese. In between were Latinos (43%) and whites (36%).,

The two reports suggest that the U.S. obesity epidemic continues to worsen and that efforts to encourage Americans to lose or stop putting on more weight are having little effect.

Worldwide increase in obesity

A study that was published in Lancet reports an alarming worldwide increase in the prevalence of obesity.

The authors estimated incidence and trends in mean body-mass index (BMI) categories, of males and females in 186 countries.

The researchers gathered population-based data that measured the height and weight of 19 million adults (9·9 million men and 9·3 million women) for which estimates were made.  They used statistical methods to estimate trends in global and national weight patterns from 1975 to 2014.  During this period global age-standardized mean BMI increased from 21·7 kg/m² to 24.2 kg/m² in in men, and from 22·1 kg/m² in to 24·4 kg/m² in women (normal BMI range is 18.5 to 22.1 kg/m²⁾. Regional mean BMIs in 2014 for men ranged from 25 kg/m² in central Africa and south Asia to 29.2 kg/m² in Polynesia and Micronesia; for women the range was from 21.8 kg/m² in south Asia to 32.2 kg/m² in Polynesia and Micronesia (BMI for the overweight category ranges from 25 kg/m² to 30 kg/m², for the obese from 30 kg/m² to 35 kg/m² while those individuals having a BMI over 35 are morbidly obese).  Finally 2.3% of the world's men and 5·0% of women were morbidly obese (i.e., have BMI ≥35 kg/m²).

Over the past 40 years there has been an unprecedented increase in the number of obese adults worldwide, climbing to about 640 million from 105 million in 1975.  If the post-2000 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.  The study found that the number of obese people surpasses the number of people who are underweight.