American Mortality Improvement Rate Slowed Due To Rise In Obesity

Obesity is a present-day health problem due to numerous factors, like genetics, the food that we eat, lack of exercise or the kind of lifestyle we are into. It happens when a person eats more calories than what he/she used to, then it dramatically builds up too much fat in his/her body. The condition could increase risks of cancer, diabetes, arthritis, stroke, and cardiovascular diseases.

Studies show that there has been a decrease in the rate of improvement in American mortality during the last three decades. According to a recent study, the upsurge in obesity is to be blamed.

The research was performed by Samuel Preston, a sociology professor at University of Pennsylvania; Yana Vierboom, a graduate student in demography at Penn; and Andrew Stokes, assistant professor of global health at Boston University.

Together, they gathered data from successive cohorts of the National Health and Nutrition Examination Survey from 1988 to 1994 and 1999 to 2010, as well as from the NHANES linked mortality files, which include follow-up into death records through December 2011. The final sample comprised of 25,269 adults aged 40 to 79.

Instead of using the usual measure for obesity “body mass index,” (BMI), recorded at reference point, the researchers calculated each person’s lifetime maximum BMI. They found this measure to be more effective at forecasting mortality because it is less susceptible to weight loss associated with illness.

In the study, the United States had the slowest decline in mortality rate with 1.53%/y at ages 40-84 among 15 countries between 1988 and 2011. The mean rate of decline for the remaining countries was 2.21%/y.


Annual rates of mortality decline among adults ages 40–84 in 16 OECD countries, 1988–2011. Mortality decline is shown for adults ages 40–85 in the United States and 15 comparable OECD countries between 1988 and 2011, if all countries had the same age distribution of 40–84 y olds as in the 2000 US Census. Data from the Human Mortality Database.


Researchers assessed that the mortality drop in the U.S. would have been about a half-percentage point faster than it really was if obesity hadn’t increased. According to the data, if age-specific death rates had fallen at the BMI-uncontrolled rate of 1.81 percent per year, life expectancy at age 40 would have risen from 37.6 years in 1988 to 41.4 years in 2011. If death rates had fallen at the BMI-controlled rate of 2.35 percent per year, life expectancy at age 40 in 2011 would have risen to 42.3 years. This evaluation points that rising BMI reduced gains in life expectancy at age 40 by 0.9 years during this period.