Issue 16 — December 17, 2008
The Bulge: Looking at Body Shape
It turns out, not all fat is created equal. While the evidence continues to accrue that obesity increases the risk of developing cancer – along with other chronic diseases – a growing number of studies point to abdominal fat as the greatest culprit.
Now, a large study of almost 360,000 participants coordinated by Elio Riboli, MD, one of the key scientific contributors to AICR’s expert report, has found that a large waistline almost doubles the risk of an early death, even when the body mass index reads in the “normal” range. Body mass index (BMI) is the most-commonly used measure of obesity.
“Our study shows that accumulating excess fat around your middle can put your health at risk even if your weight is normal based on body mass index scores. There aren't many simple individual characteristics that can increase a person's risk of premature death to this extent, independently from smoking and drinking," said Dr. Riboli, head of the Department of Epidemiology and Public Health at Imperial College London, according to the university’s statement.
The new study adds strong evidence that people and health practitioners need to look at body shape along with BMI. BMI takes into account height and weight, but not body shape or location of adipose tissue.
Waist circumference and waist-to-hip ratio (WHR), in contrast, provide measures of girth that focus on the amount of fat concentrated around the middle. (Waist-to-hip ratio is the waist circumference divided by hip circumference.) Lower WHRs mean that the waist is relatively small compared to the hips.
The study, published in last month’s New England Journal of Medicine, comes from one the largest investigations of diet and cancer ever undertaken (see box). After tracking the large group of European participants for an average of almost ten years, the researchers found that those with the largest waist circumference had almost twice the risk of dying as those with the smallest.
The higher the waist circumference; the greater the risk of death. A higher WHR was also linked to an increased mortality risk in both men and women.
The EPIC findings also support a wide body of research – including AICR’s expert report – showing the health dangers of excess body fat. Participants with a high BMI, compared with those in the medium range, died more often from cardiovascular diseases or from cancer. The lowest risk of death was at a BMI of approximately 25.3 in men and 24.3 in women.
"Although smaller studies have suggested a link between mortality and waist size, we were surprised to see the waist size having such a powerful effect on people's health and premature death,” said Dr. Riboli.
For strategies to lose excess fat and/or maintain a healthy weight, read The New American Plate.
At the beginning of the two-year study, participants had lost an average of 124 pounds and maintained weight loss for an average of 5.5 years. At the one and two-year mark, there was no major difference in caloric intake or amount of weight regain – both groups regained about 4 pounds a year – but habits in food choices and exercise were markedly different. Approximately 32 percent of the non-surgical participants lost weight without professional help.
Children who lived in greener neighborhoods gained less weight over a two-year period than a comparison group, regardless of residential density, a new study has found. Published in the American Journal of Preventative Medicine, the study looked at youth ages 3 to 16 who lived at the same address for at least two years. “Greenness” levels were identified and measured via satellite images. Previous studies have linked greener neighborhoods, associated with parks and recreational areas, to more time spent outdoors and physical activity. In this study, which did not measure physical activity, the differences linked with weight gain were regardless of age, race, or sex. Because obese children are more likely to grow into overweight or obese adults, increasing the risk for cancer and other chronic disease, it’s important for continued investigations into neighborhood greenness and preventing weight gain, note the authors.
Previous studies have found that speedy eating leads to greater food intake. Now a study has concluded that our eating speed may be a heritable trait that is related to weight. The study, published in this month’s The American Journal of Clinical Nutrition, videotaped approximately 250 twin children eating small sandwiches and fruit at home. Some of the twins were genetically identical and the others were fraternal, sharing about fifty percent of their genes. After five researchers independently analyzed the videotapes, the scientists found that the genetically identical twins had more similar eating rates than the fraternal twins. Faster eating was linked to a higher BMI among all the children. Given that the home environment was the same for each set of twins, the results indicate that eating speed has a heritable component, conclude the authors.All active news articles