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article in AR Overweight? Cutting Body Fat
Before Dietary Fat Is BetterBy Judy McBride March 6, 2000BOSTON, Mass., March 6,
2000--Are you overweight--with a body mass index (BMI) between 25 and
30--and your blood lipids are higher than your doctor would like? Then you will
probably benefit more from cutting those extra pounds, by eating fewer calories
and increasing physical activity, than from cutting dietary fat. Thats
the gist of findings in this months Agricultural Research magazine,
published by the U.S. Department of
Agricultures Agricultural Research Service. Two different heart-healthy diets were less effective at improving the
cholesterol profile of overweight men than of normal-weight men, said Jose
Ordovas at the Jean Mayer USDA Human
Nutrition Research Center on Aging at Tufts University in Boston. Ordovas
collaborated on the study, which was done in Spain by researchers at the
University of Cordoba Medical School. ARS administrator Floyd Horn noted that theres already good evidence
that dietary changes dont have much of an effect on the blood lipids of
obese people, those who have a BMI over 30. Dr. Ordovas and his Spanish
colleagues wanted to see if this carried over to people who are overweight but
not obese, Horn said. Apparently it does. Total cholesterol in the overweight men dropped less than half that of the
lean men--7 versus 16 percent--after switching from a diet high in total fat
and saturated fat to one recommended by the
National Cholesterol
Education Program (NCEP). Likewise, artery-damaging LDL cholesterol dropped
9 percent in the overweight group versus 21 percent in the lean group. The NCEP
diet is low in fat--28 percent of total calories--with only 10 percent
saturated fat. A second heart-healthy diet also had less impact on total and LDL
cholesterol in the overweight men. Although this diet was high in fat--38
percent of total calories--more than half of it was monounsaturated fat (22
percent), the predominant fat in olive or canola oils. The researchers concluded: Its more important for overweight
people to lose weight than change the fat composition of their diets. People are generally considered overweight if their BMI is between 25 and
30. Thats equivalent to a 6-foot person weighing between 185 and 220
pounds; a 5-foot, 8-inch person between 165 and 195 pounds; or a 5-foot, 4-inch
person between 146 and 170 pounds. However, individuals who are very muscular can have such a high BMI without
being overweight. To calculate your BMI, multiply your weight in
pounds by 700, then divide the total by your height in inches and divide that
result by your height in inches once more. Or you can search for one of several
BMI calculators on the Web. Indiana
University supports one at: http://www.iupui.edu/~psych/info/notes/bmi.html
While being overweight dampened the effect of dietary fat changes on
cholesterol in the study volunteers, it had the opposite effect on their blood
triglycerides. Thats a measure of how much fat is in circulation. After
consuming the diet high in monounsaturated fat for four weeks, the overweight
group had a much bigger drop in triglycerides than the lean mens group:
26 percent versus 4 percent. High triglycerides are associated with reduced glucose tolerance,
which is the earliest stage of diabetes, explains Ordovas. And evidence
is mounting that high trigylcerides independently increase risk of heart
disease. Based on these findings, it appears that portly people
should substitute olive or canola oil for saturated fat in their diet,
said Ordovas. The Agricultural Research magazine article on this topic is online.
The Agricultural Research Service is
the chief scientific arm of the U.S. Department of Agriculture. Scientific contact: Jose M. Ordovas, Jean Mayer USDA Human Nutrition
Research Center on Aging at Tufts University, Boston, Mass., phone (617)
556-3102, fax (617) 556-3103, [email protected]. U.S. Department of Agriculture |