Obesity Cuts Life Span for Young Adults, Too

LINDSEY TANNER / AP 7jan03

CHICAGO -- Being obese at age 20 can cut up to 20 years off a person's life, with the biggest impact on black men, according to yet another study that underscores the long-term dangers of being overweight.

The research appears in Wednesday's Journal of the American Medical Association and was released a day after another study that said that being fat at 40 shortens a person's life by at least three years.

The JAMA study, led by University of Alabama at Birmingham biostatistician David Allison, found that life expectancy for 20-year-olds with a body-mass index of at least 45 is 13 years lower for white men and 20 years lower for black men, compared with people of normal weight.

Body-mass index is a height-to-weight ratio; 30 and above is considered obese. A person who is 5-foot-4 and 262 pounds would have a BMI of 45 -- and look like a sumo wrestler. But millions of Americans are that fat, Allison said.

The life-shortening effects were found to be lower for 20-year-old severely obese white women (eight years of life lost) and black women (five years lost).

Obesity increases the risk for several life-threatening conditions, including heart disease, diabetes and some types of cancer. Allison said younger people are especially vulnerable, in part because they have more years to live and more time for the obesity to take its toll.

Dr. Jo-Ann Manson of Harvard's Brigham and Women's Hospital said the study helps emphasize that obesity is far worse than just "a cosmetic problem."

Until this week, data attempting to quantify the effects of obesity on life span were scarce.

In Tuesday's Annals of Internal Medicine, Dutch researchers presented data on about 3,400 mostly white, middle-aged Americans. The researchers found that being overweight at 40 is likely to reduce life expectancy by at least three years -- as much, they said, as smoking cigarettes. Obese, or severely overweight people, lost even more years -- about six or seven.

The JAMA study was based on an analysis of nationally representative surveys of more than 14,000 Americans.

Life-shortening effects were less dramatic in people who were less obese. And there were startling racial differences in how fat people had to be before life expectancy started to drop.

In blacks, life expectancy was not shortened in obese men with BMIs under 31 and in obese women under 37. But in whites, reductions of about one year occurred in young people who were merely overweight -- in men with a BMI of about 25.5 and in women with a BMI of about 27.5.

BMIs between 25 and 30 are considered overweight; the ideal is between 18 and 25.

Allison said the reasons for the racial differences are unclear. But some researchers have speculated that blacks may have relatively more lean mass, or muscle, than fat.

A JAMA editorial said the differences may be due to limitations in the study.

"It would be a great disservice to blacks if these results were used to promulgate the concept that excess weight is not harmful to them," said Manson and Shari Bassuk of Brigham and Women's Hospital.

JAMA
Abstract

Years of Life Lost Due to Obesity

Kevin R. Fontaine, PhD; David T. Redden, PhD; Chenxi Wang, MD; Andrew O. Westfall, MS; David B. Allison, PhD

Context Public health officials and organizations have disseminated health messages regarding the dangers of obesity, but these have not produced the desired effect.

Objective To estimate the expected number of years of life lost (YLL) due to overweight and obesity across the life span of an adult.

Design, Setting, and Subjects Data from the (1) US Life Tables (1999); (2) Third National Health and Nutrition Examination Survey (NHANES III; 1988-1994); and (3) First National Health and Nutrition Epidemiologic Follow-up Study (NHANES I and II; 1971-1992) and NHANES II Mortality Study (1976-1992) were used to derive YLL estimates for adults aged 18 to 85 years. Body mass index (BMI) integer-defined categories were used (ie, <17; 17 to <18; 18 to <19; 20 to <21; 21 to 45; or 45). A BMI of 24 was used as the reference category.

Main Outcome Measure The difference between the number of years of life expected if an individual were obese vs not obese, which was designated YLL.

Results Marked race and sex differences were observed in estimated YLL. Among whites, a J- or U-shaped association was found between overweight or obesity and YLL. The optimal BMI (associated with the least YLL or greatest longevity) is approximately 23 to 25 for whites and 23 to 30 for blacks. For any given degree of overweight, younger adults generally had greater YLL than did older adults. The maximum YLL for white men aged 20 to 30 years with a severe level of obesity (BMI >45) is 13 and is 8 for white women. For men, this could represent a 22% reduction in expected remaining life span. Among black men and black women older than 60 years, overweight and moderate obesity were generally not associated with an increased YLL and only severe obesity resulted in YLL. However, blacks at younger ages with severe levels of obesity had a maximum YLL of 20 for men and 5 for women.

Conclusion Obesity appears to lessen life expectancy markedly, especially among younger adults.

JAMA. 2003;289:187-193

Author/Article Information

Author Affiliations: Division of Rheumatology, Johns Hopkins University School of Medicine, Baltimore, Md (Dr Fontaine) and Department of Biostatistics (Drs Redden, Wang, and Allison and Mr. Westfall), Section on Statistical Genetics, Clinical Nutrition Research Center (Drs Wang and Allison), University of Alabama, Birmingham.

Corresponding Author and Reprints: David B. Allison, PhD, Department of Biostatistics, University of Alabama, 327 Ryals Public Health Bldg, 1665 University Blvd, Birmingham, AL 35294 (e-mail: dallison@ms.soph.uab.edu). Author Contributions: Study concept and design: Fontaine, Allison.

Acquisition of data: Allison.

Analysis and interpretation of data: Redden, Wang, Westfall, Allison.

Drafting of the manuscript: Fontaine, Wang, Allison.

Critical revision of the manuscript for important intellectual content: Fontaine, Redden, Wang, Westfall, Allison.

Statistical expertise: Redden, Wang, Westfall, Allison.

Obtained funding: Allison.

Administrative, technical, or material support: Fontaine, Redden, Allison.

Study supervision: Redden, Allison.

Funding/Support: This research was supported in part by National Institutes of Health grant P30DK56336 and a grant from the Arthritis Foundation.

source: http://jama.ama-assn.org/issues/current/abs/joc20945.html 8jan02