“Hidden” fat poses serious health risk

But exercise can take off invisible pounds and reduce risks of cancer, heart disease and diabetes.

Postmenopausal women who exercise regularly won’t necessarily see dramatic changes on their bathroom scales or in their dress sizes, but according to a new study the workouts can have a significant beneficial impact.

They can “exorcise” invisible intra-abdominal body fat that wraps itself around internal organs and may pose a greater health risk than more obvious “love handles” or bulging bellies. It is dangerous, researchers say, partly because it’s invisible.

“When you look in the mirror, you don’t know how much you have,” said Melinda L. Irwin, M.P.H., Ph.D., assistant professor of epidemiology at the School of Public Health and lead author of the study published in the January 15 issue of JAMA: The Journal of the American Medical Association.

Women, who gain an average of a pound per year, tend to accumulate it after menopause, and men are also susceptible to health risks as they gain weight around their middles. Although thin women can have intra-abdominal fat, those with waist circumferences of more than 35 inches are the most likely candidates. According to Irwin this hidden fat has been linked to insulin resistance, type 2 diabetes, hypertension, cardiovascular disease and high cholesterol levels, and increases the risk of breast and colon cancers. Intra-abdominal body fat is a metabolically active fat tissue because of its shared circulation with the organs it surrounds.

The study, conducted by Irwin and colleagues at the Fred Hutchinson Cancer Research Center in Seattle, Wash., looked at 173 physically inactive postmenopausal women between the ages of 50 and 75. The women were assigned to one of two groups; one exercised at a moderate intensity five days a week and the other merely stretched one day a week. The researchers measured changes in weight and body fat at the start of the study and after one year.

“While overall weight loss was modest for the women who exercised, intra-abdominal body fat loss was statistically and clinically significant,” said Irwin. The study found that women who exercised moderately five times a week saw a 6 to 11 percent decrease in intra-abdominal body fat. “That would translate into a reduced risk of cardiovascular disease and cancer,” Irwin said. “The good news,” she said, “is that even if exercise doesn’t seem to be making any visible difference—women only lost, on average, three pounds—moderate exercise such as brisk walking reduced hidden fat.”

According to Irwin, most studies that examine the correlation between weight and exercise just weigh the test subjects and measure their waist circumferences. This merely measures weight, not total body fat or fat distribution. “Usually they conclude that exercise has minimal or no effect on body weight,” Irwin said. “We agree with them, except they’re not taking into consideration body fat and how it is distributed on the body.”

Irwin said she and her colleagues used computed tomography—“which is a lot more sensitive than just getting on a scale and measuring weight”—to gauge the test subjects’ amount of intra-abdominal tissue. Using this method, the researchers were able to observe a statistically significant effect of exercise on the intra-abdominal tissue.

The message to take away from this study, Irwin said, is that if you are getting frustrated because you are exercising but not losing any weight, keep at it. “Even if you think you aren’t getting any benefit, you really are.” She also noted that when weight is lost through exercise, rather than diet, you have a better chance of keeping it off. “Dieting hasn’t been shown to be good for weight maintenance; you gain it back, whereas if someone exercises to lose weight, they’re more likely to maintain the weight loss,” Irwin said.

—Jennifer Kaylin

Ovarian tumors need not cause infertility

A conservative approach to the treatment of a rare form of ovarian cancer, called ovarian germ cell malignancies, allows young women to conceive afterwards, Yale scientists have found. In a study published in the February issue of Obstetrics & Gynecology, Peter E. Schwartz, M.D., HS ’70, the John Slade Ely Professor of Obstetrics and Gynecology, followed the cases of 86 women, most of whom had undergone fertility-preserving treatment in which only the affected ovary was removed. Of 38 women who attempted to conceive, 29 became pregnant. To date, their children have shown no developmental abnormalities.

—John Curtis

Et Cetera

Seizures and drug resistance

Researchers have shown for the first time how long it takes to establish resistance to drugs that control partial epilepsy. A multicenter study directed by Susan S. Spencer, M.D., FW ’78, professor of neurology, and published in the journal Neurology in February examined 333 patients to analyze outcomes of surgical treatment of partial epilepsy and to identify factors that predict when seizures become intractable. About 80 percent of those with partial epilepsy cannot control seizures with medications.

Researchers found that an average of about nine years passed before at least two drugs failed to control recurrent seizures. During that interval, a quarter of those in the study had remissions lasting up to a year and slightly fewer than 9 percent had remissions of five years or more. A younger age at the onset of seizures predicted longer seizure-free intervals. “This kind of information,” Spencer said, “leads us to explore the mechanisms by which treatment resistance develops over so many years, and prompts consideration and investigation of preventive strategies for the future.”

—John Curtis

A new cardiac risk factor

Women with a history of pre-eclampsia are at increased risk for cardiovascular disease, according to a study presented in February at the Society for Maternal-Fetal Medicine annual meeting in San Francisco.

“Pre-eclampsia should be added to the list of risk factors for cardiovascular disease, possibly equal to issues such as obesity, smoking and diabetes,” said Edmund F. Funai, M.D., assistant professor of obstetrics and gynecology and the study’s lead author.

Pre-eclampsia, a progressive disease that occurs late in pregnancy and affects about 5 percent of women, can cause slower-than-normal fetal growth and put women at risk of lung, kidney and liver problems. High blood pressure is an early warning sign of pre-eclampsia. The study by researchers at Yale and in Israel tracked the death rates of 34,000 women who gave birth between 1964 and 1976.

—John Curtis


			Originally published in Yale Medicine, Summer 2003. Copyright © 2003 Yale University School of Medicine. All rights reserved.