When it comes to body fat, today's older adults face a double whammy, according to new research from Wake Forest University School of Medicine and colleagues. Up until age 80, older adults not only gain fat as they age -- but because of the obesity epidemic -- they actually begin their older years fatter.
The result is an increased risk of diabetes, heart disease, high blood pressure, arthritis and disability, according to Jingzhong Ding, M.D., Ph.D., lead author and a researcher on aging at Wake Forest Baptist.
The study, reported in the current issue of the American Journal of Clinical Nutrition, focuses on changes in body composition related to aging and in the population over time. It is significant because the researchers used DEXA (dual-energy X-ray absorptiometry) to measure actual body fat to determine the proportion of fat versus lean mass (muscle and organs).
The measurements were made on 1,786 well-functioning older adults from Pittsburgh, Pa., and Memphis, Tenn., from 1997 to 2003. Participants were 70-79 at the time of enrollment, a critical period for the development of disability. Body composition -- especially the combination of too much body fat and a decrease in muscle -- is believed to contribute to disability.
"This study provides a better picture of age-related changes in body composition and it's not a good picture," said Ding, an assistant professor of gerontology and geriatric medicine. "It demonstrates that up until age 80, both older men and women gained fat but lost lean mass each year. These age-related changes were compounded by the obesity epidemic."
In addition to measuring the effects of aging on body composition, the researchers also looked at the effects of the obesity epidemic, which most scientists agree began in the late 1970s. Between 1976-80 and 1999-2000, the rate of obesity doubled in older adults.
The scientists divided participants into 10 groups based on their birth years (from 1918 to 1927). They found that at the same age, those born later -- who had spent more years during the period when obesity was increasing -- had a higher percentage of body fat. For example, among 80-year-old men, those born in 1927 had about 10 pounds more fat and 3.75 pounds of muscle, compared to those born in 1918.
"The combined effects of aging and the obesity epidemic results in bigger body size and less lean mass among the elderly," said Ding. "This may lead to disability and other illnesses in the elderly and could be dramatic in the coming years. It points out the great public health importance of developing appropriate interventions that target fat loss while preserving skeletal muscle to prevent disability and other obesity-related illnesses."
The research was supported, in part, by the National Institute on Aging. The researchers analyzed data from the Health Aging and Body Composition (ABC) Study, a large study investigating the effects of body composition on morbidity, disability and mortality in the elderly.
Other centers involved in the study were the University of Pittsburgh, University of Queensland in Australia, UV Medical Center in the Netherlands, University of North Carolina at Chapel Hill, University of California at San Francisco, University of Tennessee Health Science Center, University of Florida and North Florida/South Georgia Health System.
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