Both obesity and smoking are risk factors for lower life expectancy and quality of life. According to a new study published in the New England Journal of Medicine, the negative health effects of the trend toward increasing obesity in the United States is forecast to outweigh the positive effects gained from declining smoking rates.

Scientists from Harvard University and their colleagues sought to gain a better understanding of the combined effects of obesity and smoking on U.S. longevity. For each year from 2005 through 2020, they forecasted the life expectancy for a representative 18-year-old, assuming a continuation of past trends in smoking and body mass index. They found that the negative effects of increasing obesity overwhelmed the positive effects of declines in smoking, leading to a 0.71 year reduction in life expectancy. Based on their forecasts, the study authors indicated that, if all U.S. adults were to become nonsmokers of normal weight by 2020, the life expectancy of an 18-year-old would increased by 3.76 years.

Although increases in obesity over the past 30 years have had a negative impact on the health of the U.S. population, there have been simultaneous improvements in health because of reductions in smoking. However, it seems that, if past obesity trends continue, these increases in obesity could erode the overall gains in health that have been observed over the past 100 years. This study highlights yet another reason that addressing obesity is an important part of positive aging.
 

Source:

NEJM. 2009;361(23):2252-2260.