
Lift Weights to Lift
Aging Metabolism, Lower Weight GainBy Judy McBride January 11, 2001
A comprehensive study funded by the Agricultural Research Service might allay
any lingering debate about why metabolism slows as people age. The new findings
show that the gradual loss of body cells, especially those
high-energy-consuming muscle cells, can help explain why older people burn
fewer calories while at rest--which so often leads to creeping weight gain. Some scientists have suggested that changes in hormones, immune function or
other factors may depress resting metabolism with aging. But this study--a
statistical analysis conducted by researchers at the
Human Nutrition Research Center on Aging
at Tufts University in Boston--showed a direct association between
metabolic rate and cell mass, also known as lean- or fat-free mass. And thats good news. It means that older people may regain some of
their youthful resting metabolic rate by regular muscle-building exercises.
Increasing muscle mass would help seniors get off the slow boat to obesity,
according to the researchers. For their analysis, they used measurements of body composition and resting
metabolic rate for 131 healthy men and women taken over the last five years at
the Boston center. The subjects ranged in age from 18 to 87, giving the
researchers a broad sample for detecting small changes in cell mass across the
years. But they found that only one of the six methods used to measure the
subjects body composition exposed the decline in cell mass occurring with
age. That was a high-tech method for measuring the bodys total
potassium--a mineral found almost entirely inside of cells. Related studies at the center further support an age-related loss of cell
mass. Researchers found a definite decline in muscle mass of middle-aged and
senior men and women over 10- and 12-year periods when they measured the
subjects leg muscles by computerized tomography--or CAT scan. The
shrinkage of muscle tissue explained at least half of the subjects loss
of strength in those muscles. ARS is the U.S. Department of
Agricultures chief research arm. Scientific contact: Ronenn Roubenoff, Jean Mayer USDA Human Nutrition
Research Center on Aging at Tufts
University, Boston, Mass., phone (617) 556-3172, fax (617) 556-3083,
[email protected]. U.S. Department of Agriculture |