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.

Aspirin use decreases the risk of gastrointestinal cancers

Research by Cao et al published in JAMA Oncology suggests that regular aspirin use may be associated with lower risk of certain cancers.

The investigators looked at data on approximately 136,000 individuals who enrolled at two large US prospective cohort studies, the Nurses’ Health and Health Professionals studies. 

Among the 88 084 women and 47 881 men who underwent follow-up for as long as 32 years, 20 414 cancers were detected among women while 7571 cancers were found in men. Compared with nonregular use, regular aspirin use was associated with a lower risk for overall cancer, which was primarily due to a lower incidence of gastrointestinal tract cancers especially colorectal cancers. The benefit of aspirin on gastrointestinal tract cancers appeared evident with the use of at least 0.5 to 1.5 standard aspirin tablets per week; the minimum duration of regular use associated with a lower risk was 6 years. Among individuals older than 50 years, regular aspirin use could prevent 33 colorectal cancers per 100 000 person-years (PAR, 17.0%) among those who had not undergone a lower endoscopy and 18 colorectal cancers per 100 000 person-years (PAR, 8.5%) among those who had.

The researchers found that taking aspirin regularly—defined twice a week or more—for at least six years was associated with a 19% drop in risk for colon and rectum cancers, a 15% lower risk for gastrointestinal tract cancers and a 3% lower risk for cancers in general. The researchers did not find a link between regular aspirin use and risk reduction for some other cancers, including cancers of the breast, prostate and lung.

The benefits for GI cancers seemed to manifest even with a lower dose of aspirin, starting with half a standard aspirin tablet weekly. The authors found that taking aspirin regularly could prevent anywhere from 8-17% of colorectal cancers in people older than 50.

The authors concluded that long-term aspirin use was associated with a modest but significantly reduced risk for overall cancer, and may prevent a substantial proportion of colorectal cancers and thus complement the benefits of screening.