Heli J. Roy | 10/15/2004 1:37:37 AM
"Having too much body fat is bad for our health, but the distribution of body fat is also very important," the nutritionist points out. She notes that body shape is usually classified into two distinct types: apples and pears.
"Apple-shaped people have most of their excess fat around their abdominal area, surrounding internal organs, such as the heart," Roy explains. The fat around the abdomen is physiologically more active than fat in the arms and legs.
"Thus, apple shapes have a higher risk of diabetes, heart disease, stroke, high blood pressure and gall bladder disease," Roy says. The fat from the abdominal stores is easily released into the bloodstream and can accumulate in the blood vessels and interfere with insulin action and glucose absorption. These are some of the early symptoms of diabetes.
"Pear-shaped people, on the other hand, carry their excess fat on their hips and thighs," Roy continues, adding, "Since most of the fat is in less active form, pear-shaped people do not have as high a risk of developing chronic diseases."
Abdominal fat is important even in lean individuals. Those individuals who have more abdominal fat, although lean, have higher risk of insulin resistance and potential for developing Type 2 diabetes than lean individuals with less abdominal fat.
Does race play a role among apple-shaped people? Drs. Tuomo Rankinen and Claude Bouchard from the Pennington Biomedical Research Center in Baton Rouge, together with researchers from the University of Texas, University of Houston, Texas A&M University, Laval University, University of Minnesota, Washington School of Medicine and Indiana University assessed if the effects of race, age and subcutaneous fat on abdominal fat are different between black and white subjects.
This was part of the Heritage Family Study, a large, multicenter clinical trial primarily focused on investigating the probable genetic basis for the variability in individual responses to aerobic exercise training with respect to risk factors for cardiovascular disease and Type 2 diabetes, as well as for various physiological measures.
Data from 692 men and women were collected. The population included 91 black men, 137 black women, 227 white men and 237 white women ages17-65. Fat in the abdominal region was measured as were skinfold thicknesses and waist, hip and arm circumferences.
The men were taller, heavier and leaner than the women. The total fat weight for black women was higher than that of white women. This phenomenon was associated with a higher total body weight, body mass index and percent body fat and larger waist and hip circumferences and skinfolds in the black women.
Total abdominal fat for white men was higher than that for black men. Abdominal visceral fat of white men and white women was significantly higher than that of their black counterparts. Black men and women had significantly less abdominal visceral fat than white men and women. This difference was greater in men than in women. Abdominal visceral fat increased with age in both sexes.
"This study suggests that there is a difference in abdominal fat content between the races, with white men and women having greater visceral fat content than black men and women," Roy observes. The difference is more pronounced in the men.
"Since visceral fat is the metabolically active fat in the abdominal area and is associated with higher incidence of chronic diseases, the results from this study suggest that white men and women should have a higher incidence of hypertension, heart disease and diabetes than black men and women," the LSU AgCenter nutritionist says, but counters, "However, hypertension, heart disease and diabetes are much more prevalent in black men and women than in white men and women."
She says diabetes risk alone is about 2.4 times greater for black women than for white women. The prevalence of dyslipidemia (dietary fat problems) is higher in men than in women and is somewhat higher in the white than in the black population. This could be explained by the results found in this study.
"These chronic diseases, however, have multifaceted causes," Roy says, "including environment, diet, health care, family history and cultural habits, to name a few."
To assess the risk of chronic diseases, Roy offers a simple test. She says to measure the circumference of waist and hip to get a ratio. In men, an ideal waist-to-hip ratio is 0.95 or less, and in women 0.8 or less.
"It is important to retain ratios at or below these values as one ages to try to prevent the development of chronic diseases," the nutritionist stresses.