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Better fat and fit?
Thursday, March 25, 2004 5:19 am Email this article
"The health benefits of normal weights appear to be limited to men who have moderate or high levels of cardiorespiratory fitness," concluded researchers from the Cooper Institute for Aerobic Research in Dallas, Texas and from the University of Houston.
“These data suggest that the 1995 US weight guidelines may be misleading unless cardiorespiratory fitness is taken into account.”
One of their conclusions was that it was better to be overweight and fit and normal-weight and unfit.
They found that men who were overweight but fit had a lower risk of dying than normal-weight men who were unfit.
Being unfit increased the risk of dying 1.7 to 2.2 times compared to men of a similar weight who were fit.
Normal weight was defined as a Body Mass Index (BMI) of 19 to 24.9, mild-overweight as a BMI of 25 to 27.7, and overweight as 27.8 or more.
The study followed 21,856 men, ages 30- to 83-years-old for an average of 8.1 years who had been evaluated at the Cooper Institute between 1971 and 1989. Dr. Kenneth Cooper, founder of the institute, coined the term “aerobics”.
I want to believe this study, but I have a problem with the way that they defined fit and unfit.
Eighty percent of men were defined as fit.
Only 20 percent of men with the shortest treadmill times were defined as unfit.
It seems to me that dividing men this way simply separates the healthy from the unhealthy. And the data seems to indicate this.
Given that everything else is equal the risk of dying normally increases as weight increases. But this is not what happened in this study.
Among unfit men, there were more deaths among those who were normal-weight than those who were either mildly-overweight or overweight (4.8 percent versus 3.5 percent versus 3.6 percent, respectively).
Statistics on each group adds additional insight into the problem.
Comparing unfit men to fit men showed smoking was 2-3 more common (31-41 percent versus 16-19 percent, respectively); a history of diabetes was 2-3 times more common (5-6 percent versus 2 percent, respectively); abnormal echocardiogram was twice as common in normal-weight and mildly-overweight unfit men (11 percent versus 6 percent, respectively); elevated blood sugar was twice as common (4-12 percent versus 2-7 percent, respectively); and an elevated systolic blood pressure reading was half again as common in unfit as fit men (11-19 percent versus 8-13 percent, respectively).
I think a more appropriate conclusion for this study would have been that healthy overweight men are less likely to die than unhealthy normal-weight men.
Lee CD; Jackson AS; Blair SN. US weight guidelines: is it also important to consider cardiorespiratory fitness? International Journal of Obesity and Related Metabolic Disorders, 1998 Aug, 22 Suppl 2:S2-7.
Lee CD; Blair SN; Jackson AS. Cardiorespiratory fitness, body composition, and all-cause and cardiovascular disease mortality in men. American Journal of Clinical Nutrition, 1999 Mar, 69(3): 373-80.
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