Tuesday, July 23, 2013

Obesity Cuts Life Short

More than 15 yeas ago we showed conclusive evidence that obesity causes many chronic conditions in the US population1-3 -, that weight gain increases risk of diabetes 4-6, heart disease 7, breast cancer 8, and that this burden adds up quickly, even before we get to overweight, let alone obesity. In the New England Journal of Medicine (report) we summarized some of this evidence 9.

With a cut off of BMI at 25 defining overweight, we see that risk of diabetes, gall stones, and high blood pressure and heart disease are all elevated, and the risk continues to rise with higher levels of adiposity or BMI. This is true in the first figure – showing the relative risks for women, and in the second for men.

Relative Risk of Diabetes, and other chronic conditions by level of Body mass Index (BMI)

Women




Men




We recently completed and analysis of national data to predict life years lost associated with obesity-related diseases for U.S. non-smoking adults, and to examine the relationship between those obesity related diseases and mortality.10 We used data from the National Health Interview Survey, 1997-2000 (see report).

We analyzed these data to estimate the association between those obesity related diseases and mortality and used simulations to project life years lost associated with the diseases.

What did we find?

We found that obesity-attributable comorbidities are associated with early mortality that leads to large decreases in life years and increases in mortality rates. The life years lost associated with obesity related diseases is more marked for younger adults than older adults, for blacks than whites, for males than females. Furthermore, the magnitude of life years lost increases with increasing level of obesity.

Using U.S. non-smoking adults aged 40 to 49 years as an example to illustrate percentage of the life years lost associated with disease caused by obesity, we found that the mean life years lost for U.S. non-smoking black males aged 40 to 49 years with a body mass index above 40 kg/m2 was 5.43 years. This translates to a 7.5% reduction in total life years lived. White males of the same age range and same degree of obesity lost 5.23 life years on average - a 6.8% reduction in total life years. For black females the numbers are: 5.04 years, a 6.5% reduction in life years, and white females they are: 4.7 years, a 5.8% reduction in life years.

Overall, diseases caused by obesity increase the chances of dying and lessened life years by anywhere from 0.2 to 11.7 years depending on gender, race, BMI classification, and age. The effect of obesity related diseases on mortality is shown for each age group in the figure below.



The epidemic of obesity in the US continues to carry a heavy burden for society 11,12, on our health care system 13,14, our businesses 15, and on our families.

References

1.         Willett W, Dietz W, Colditz G. Guidelines for healthy weight. N Engl J Med. 1999;341:427-434.
2.         Colditz GA, Coakley E. Weight, weight gain, activity, and major illnesses: the Nurses' Health Study. Int J Sports Med. Jul 1997;18 Suppl 3:S162-170.
3.         Must A, Spadano J, Coakley EH, Field AE, Colditz G, Dietz WH. The disease burden associated with overweight and obesity. JAMA. Oct 27 1999;282(16):1523-1529.
4.         Colditz GA, Willett WC, Rotnitzky A, Manson JE. Weight gain as a risk factor for clinical diabetes in women. Ann Intern Med. 1995;122:481-486.
5.         Chan JM, Rimm EB, Colditz GA, Stampfer MJ, Willett WC. Obesity, fat distribution, and weight gain as risk factors for clinical diabetes in men. Diabetes Care. 1994;17:961-969.
6.         Colditz GA, Willett WC, Stampfer MJ, et al. Relative weight and increased risk of diabetes in a cohort of US women (abstract). Am J Epidemiol. 1987;126:750-751.
7.         Willett WC, Manson JE, Stampfer MJ, et al. Weight, weight change, and coronary heart disease in women: risk within the 'normal' weight range. J Am Med Assoc. 1995;273:461-465.
8.         Huang Z, Hankinson SE, Colditz GA, et al. Dual effects of weight and weight gain on breast cancer risk. JAMA. 1997;278(17):1407-1411.
9.         Willett WC, Dietz WH, Colditz GA. Guidelines for healthy weight. N Engl J Med. 1999;341:427-434.
10.      Chang SH, Pollack LM, Colditz GA. Life Years Lost Associated with Obesity-Related Diseases for U.S. Non-Smoking Adults. PLoS One. 2013;8(6):e66550.
11.      Oster G, Thompson D, Edelsberg J, Bird AP, Colditz GA. Lifetime health and economic benefits of weight loss among obese persons. Am J Public Health. Oct 1999;89(10):1536-1542.
12.      Colditz G. Economic costs of obesity and inactivity. Med Sci Sports Exerc. 1999;31:S663-667.
13.      Thompson D, Edelsberg J, Colditz G, Bird A, Oster G. Lifetime health and economic consequences of obesity. Arch Intern  Med. 1999;159:2177-2183.
14.      Thompson D, Brown JB, Nichols GA, Elmer PJ, Oster G. Body mass index and future healthcare costs: a retrospective cohort study. Obes Res. Mar 2001;9(3):210-218.
15.      Thompson D, Edelsberg J, Kinsey K, Oster G. Estimated economic costs of obesity to U.S. business. Am J Health Promot. 1998;13:120-127.


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