Pamalicious
06-27-2004, 06:31 PM
Hazard of Weight Gain for Blacks Unclear
Sat Jun 26, 1:10 PM ET Add Health - AP to My Yahoo!
By DANIEL Q. HANEY, AP Medical Editor
While much research suggests even a little extra weight can be bad for people's health, the hazard is much less clear for black people than for whites.
Several studies show little or no association between rising weight and the risk of death for U.S. blacks, especially women. In fact, being overweight but not obese could even be a benefit rather than a hazard.
The question is why. Are blacks truly less susceptible than whites to the ill effects of fat? Or are the studies somehow so flawed that they fail to measure this effect?
"People don't know what to make of it," says Dr. Steven Heymsfield of Columbia University. "Blacks still have a lot of strokes and heart attacks, but maybe it's for reasons other than BMI."
Also unclear is whether the same is true for people of African descent in other parts of the world, experts say, since large studies like those in the United States have not been done.
One of the largest reports to look at this, an analysis of American Cancer Society (news - web sites) data on more than 1 million U.S. adults, found strong ties between weight and longevity for whites but much less solid evidence for blacks.
For instance, the study found only about a 20 percent increased risk of death among overweight black women, and even then only when their body-mass index exceeded 35, which is well into the obese range. The risk for black men began to rise when they reached the overweight category, but the increase was small.
The rising risk was not considered statistically meaningful for either men or women, but that might have been because only about 12,000 study participants were black, too few to show a clear trend.
Another review that combined data from several large population follow-ups suggests a little extra weight might actually be a good thing for American blacks. Both men and women appeared to live a bit longer than usual if their BMIs were in the overweight but not obese category.
Some question the significance of the racial comparison. They say that since blacks die younger than whites, the studies might underestimate the health effects of weight or fail to account for weight loss that results from underlying diseases.
"I don't think a direct comparison of the relative mortality risk in blacks and whites is helpful," said Shiriki Kumanyika, an epidemiologist at the University of Pennsylvania. "You would have to know the circumstances that influence death across the BMI distribution in the black population."
Still, if blacks truly suffer fewer consequences of modest weight gain, she and others speculate that differences in body fat distribution might partly explain why.
Fat is thought to be most dangerous if it is packed around the internal organs. This kind of fat is most biologically active, throwing off cholesterol levels and forcing up insulin levels.
Overweight blacks tend to have lower levels of harmful triglycerides and higher amounts of protective HDL than do similar-size whites, and this might be due to where their fat is deposited. Blacks tend to carry a larger proportion of their fat in a layer under the skin rather than deep in the belly.
Sat Jun 26, 1:10 PM ET Add Health - AP to My Yahoo!
By DANIEL Q. HANEY, AP Medical Editor
While much research suggests even a little extra weight can be bad for people's health, the hazard is much less clear for black people than for whites.
Several studies show little or no association between rising weight and the risk of death for U.S. blacks, especially women. In fact, being overweight but not obese could even be a benefit rather than a hazard.
The question is why. Are blacks truly less susceptible than whites to the ill effects of fat? Or are the studies somehow so flawed that they fail to measure this effect?
"People don't know what to make of it," says Dr. Steven Heymsfield of Columbia University. "Blacks still have a lot of strokes and heart attacks, but maybe it's for reasons other than BMI."
Also unclear is whether the same is true for people of African descent in other parts of the world, experts say, since large studies like those in the United States have not been done.
One of the largest reports to look at this, an analysis of American Cancer Society (news - web sites) data on more than 1 million U.S. adults, found strong ties between weight and longevity for whites but much less solid evidence for blacks.
For instance, the study found only about a 20 percent increased risk of death among overweight black women, and even then only when their body-mass index exceeded 35, which is well into the obese range. The risk for black men began to rise when they reached the overweight category, but the increase was small.
The rising risk was not considered statistically meaningful for either men or women, but that might have been because only about 12,000 study participants were black, too few to show a clear trend.
Another review that combined data from several large population follow-ups suggests a little extra weight might actually be a good thing for American blacks. Both men and women appeared to live a bit longer than usual if their BMIs were in the overweight but not obese category.
Some question the significance of the racial comparison. They say that since blacks die younger than whites, the studies might underestimate the health effects of weight or fail to account for weight loss that results from underlying diseases.
"I don't think a direct comparison of the relative mortality risk in blacks and whites is helpful," said Shiriki Kumanyika, an epidemiologist at the University of Pennsylvania. "You would have to know the circumstances that influence death across the BMI distribution in the black population."
Still, if blacks truly suffer fewer consequences of modest weight gain, she and others speculate that differences in body fat distribution might partly explain why.
Fat is thought to be most dangerous if it is packed around the internal organs. This kind of fat is most biologically active, throwing off cholesterol levels and forcing up insulin levels.
Overweight blacks tend to have lower levels of harmful triglycerides and higher amounts of protective HDL than do similar-size whites, and this might be due to where their fat is deposited. Blacks tend to carry a larger proportion of their fat in a layer under the skin rather than deep in the belly.