Explaining Divergent Levels of Longevity in High-Income Countries (2011) / Chapter Skim
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3 The Role of Obesity
3 The Role of Obesity
Pages 43-55
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From page 43... ...
. So it is natural to ask whether the higher rates of obesity in the United States may help explain the divergence in life expectancy trends that has been observed over the past quarter of a century.
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From page 44... ...
Obesity Trends in the United States and Other Countries One of the most striking health-related trends in the United States over the past 50 years has been the rise of obesity. As can be seen in Figure 3-1, in 1960-1962 only 10.7 percent of adult males and 15.8 percent of adult females in the country were obese.
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From page 45... ...
During the same quarter century, adult male obesity rates were also increasing in the other high-income countries, so that by 2003 only Japan and Italy had rates below 10 percent. Canada and England, at 23 percent, had the highest rates after the United States.
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From page 46... ...
Canada 30 Denmark 25 England France 20 Italy 15 Japan 10 Netherlands Spain 5 USA 0 1978 1981 1984 1987 1990 1993 1996 1999 2002 2004 Year FIGURE 3-2 Trends in prevalence of adult obesity by country and gender, 1978 2004. NOTE: Age ranges vary.
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From page 47... ...
The data on obesity rates for older adults are not as complete as they are for all adults, but as can be seen in Figure 3-3, the existing data show similar trends for this group. In particular, the rates in the United States are again higher than those in the other high-income countries, although the divergence is not as great.
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From page 48... ...
; Netherlands: measured height and weight from three cities (Schokker et al., 2007) ; United States: mea sured height and weight (Flegal et al., 2002)
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From page 49... ...
had been responsible for 365,000 excess deaths among U.S. adults in 2000, making it the second-leading preventable cause of death in the United States, behind only smoking (Mokdad et al., 2005)
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From page 50... ...
Complicating the discussion of weight and mortality is the fact that as BMI decreases below normal range, mortality increases. Virtually all studies find that the curve of mortality risk and BMI is U-shaped or J-shaped, with mortality somewhat higher at the low- and high-BMI ends (e.g., Flegal et al., 2005; Prospective Studies Collaboration, 2009)
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From page 51... ...
A sedentary older adult may lose half a pound of muscle mass per year, or 5 pounds a decade, significantly altering the meaning of BMI. More important, older adults also are more likely to have various existing diseases and to have experienced illness-related weight loss, either of which can confound the relationship between weight and mortality risk.
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From page 52... ...
Among males, the life expectancy at 50 in the United States was eighth highest out of the 10, ahead of only the Netherlands and Denmark, and the rate of obesity among U.S. males was the highest of any of the countries.
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From page 53... ...
The numbers were similar for white women but not for black men and women; for those in the latter groups, obesity shortened life only among younger people and those with a very high BMI. Estimating the contribution of differences in obesity to the life expectancy gap between the United States and other countries requires an attributable risk approach that combines BMI distributions in different countries with sets of mortality risk associated with BMI.
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From page 54... ...
Because the proportions obese are higher in the United States than elsewhere, especially at the upper extremes of BMI, these hypothetical changes from eliminating obesity are substantially larger than those in any other country. As noted above, there is suggestive evidence that the mortality risk associated with obesity has been declining in the United States (Flegal et al., 2005; Mehta and Chang, 2010)
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From page 55... ...
The panel is inclined to believe that the two sets of relative risks recorded more recently in the United States yield more reliable estimates of the impact of obesity on life expectancy comparisons than those obtained using the PSC risks. Even using the sets of lower obesity risks, however, it appears that differences in obesity account for a fifth to a third of the shortfall in life expectancy in the United States relative to other countries.
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