Obesity and increased risk of stroke

Degree of obesity raises risk of stroke, regardless of gender, race

American Heart Association rapid access journal report

The higher a person’s degree of obesity, the higher their risk of stroke — regardless of race, gender and how obesity is measured, according to a new study published in Stroke: Journal of the American Heart Association.

“It has not been clear whether overweight and obesity are risk factors for stroke, especially among blacks,” said Hiroshi Yatsuya, M.D., Ph.D., study lead author and visiting associate professor at the University of Minnesota in Minneapolis. “There are also questions about which measure of excess weight (body mass index [BMI], waist circumference or waist-to-hip ratio) is most closely associated with disease risk.”

Analyzing the ARIC Study database in which subjects’ BMI, waist circumference and waist-to-hip ratio were measured at the study’s start, Yatsuya and colleagues followed 13,549 middle-aged black and white men and women in four U.S. communities from 1987 through 2005. Participants started the study free of cancer and cardiovascular disease.

During the follow-up period of about 19 years, 598 ischemic strokes occurred. The researchers calculated incidence rate — the number of new cases per 1,000 people per year — according to groups representing different degrees of obesity, using each obesity measure.

They found that incidence rates differed substantially between whites and blacks. For example, the stroke rate in the lowest BMI category was 1.2 per 1,000 person-years for white women and 4.3 per 1,000 person-years for black women. The rate in the highest BMI category was 2.2 for white women and 8.0 for black men.

“Black women had about three times higher incidence of stroke than white women in the lowest as well as in the highest BMI categories,” Yatsuya said. “But the correlation between increasing stroke incidence and increasing degree of obesity was apparent in both races and genders.”

Individuals in the highest BMI category had 1.43 to 2.12 times higher risk of stroke (varying modestly by race and sex) compared to the lowest BMI category. When waist circumference was used as a measure of obesity instead of BMI, those risk ratios ranged from 1.65 to 3.19; and 1.69 to 2.55 when waist-to-hip ratio was used. Thus, for any obesity measure, individuals in the highest category had approximately two times higher risk of stroke compared to the lowest category in each race-sex group.

“Since individuals with higher degrees of obesity tended to have higher blood pressure levels or higher diabetes prevalence, we further examined the relationship between the degree of obesity and ischemic stroke incidence by statistically adjusting for difference in blood pressure of diabetes status attributed to the degree of obesity,” Yatsuya said. “That significantly weakened the associations, suggesting these major risk factors explain much of the obesity-stroke association.”

The study re-emphasizes the need to prevent obesity in general, Yatsuya said. But, he said, clinical trials would be needed to determine whether obesity prevention or control would actually decrease stroke incidence.

Source: American Heart Association 

Are you being your own best friend or your worst enemy?

Some obese people perceive body size as OK, dismiss need to lose weight

Some obese people misperceive that their body size is normal and think they don’t need to lose weight, according to research presented at the American Heart Association’s Scientific Sessions 2009.

In the Dallas Heart Study of 5,893 people, researchers found that 8 percent of the 2,056 who were obese said they were satisfied with their body size or felt they could gain weight.

“Almost one in 10 obese individuals are satisfied with their body size and didn’t perceive that they need to lose weight,” said Tiffany Powell, M.D., lead author of the study and a cardiology fellow at the University of Texas Southwestern Medical Center in Dallas. “That is a sizeable percentage who don’t understand they are overweight and believe they are healthy.”

Participants included about 50 percent blacks, 20 percent Hispanics and 30 percent whites, similar to other urban populations, Powell said. About half – 54 percent – were women. African Americans (14 percent) and Hispanics (11 percent) were significantly more likely than whites (2 percent) to be satisfied with their body size and believe that they did not need to lose weight.

Using the sex-specific Stunkard nine-figure scale, participants chose the figure that represented their present body size and the figure that represented their ideal body size. Self-perceived ideal body size was classified as below normal, normal and above normal. Body size discrepancy, a measure of body size satisfaction, was calculated as the difference between self-perceived actual and self-perceived ideal body sizes.

Those with a misperception of body size believed they were healthy. But 35 percent of them had high blood pressure, 15 percent had high cholesterol, 14 percent had diabetes and 27 percent were current smokers. These risk factors are similar to obese individuals who acknowledged they had a weight problem and needed to lose weight, Powell said.

Overall, 2 percent to 3 percent of the study population perceived an above-normal body size as ideal. Compared to subjects who perceived their ideal body size as normal, those who perceived ideal body size to be above normal were more likely to be women, African American and had higher body mass index, blood pressure and higher insulin resistance.

Researchers also found:

• Those who misperceived their body size were less likely to go to a physician. In fact, 44 percent didn’t visit a physician during the past year, compared to 26 percent of obese participants who correctly perceived they needed to lose weight.
• There was no significant difference between the two groups in socioeconomic status or access to health care due to insurance status.
• Among those who did see a physician in the past year, the obese individuals who did not feel they needed to lose weight were much less likely to report that their physician had told them they need to lose weight compared to those who perceived they needed to lose weight (38 percent vs 68 percent). Moreover, only 38 percent talked with their physician about dietary changes, while 64 percent of those with a more accurate body perception talked about changes.
• Obese people who were satisfied with their body size didn’t exercise, while obese individuals who recognized they had a weight problem exercised regularly, on average.

The major limitation of the study is that researchers couldn’t infer causality between associated beliefs and behaviors because the study is cross-sectional.

“This is an important population that we aren’t seeing or targeting,” Powell said. “Understanding and countering this misconception may be a novel and perhaps vitally important target for obesity prevention and treatment. Because many of these individuals believe they are healthier than they really are, they do not go to the doctor and thus community interventions will be needed. However, Powell also emphasized that her findings show that physicians need to talk with their obese patients about exercise and weight loss. “The onus falls on us as physicians to determine who this population is and how to talk with them.”

Source: American Heart Association

How much do you weight? Be honest, you’re life could depend on it…

Obese and overweight women, children underestimate true weight

Overweight and obese mothers and their children think they weigh less than their actual weight, according to research reported at the American Heart Association’s Nutrition, Physical Activity and Metabolism/Cardiovascular Disease Epidemiology and Prevention 2011 Scientific Sessions.

In the study of women and children in an urban, predominantly Hispanic population, most normal weight women and children in the study correctly estimated their body weight, but most obese women and children underestimated theirs.

“Obesity is a well-known risk factor for the development of many diseases, including heart disease and diabetes,” said Nicole E Dumas, M.D., lead author and an internal medicine resident at Columbia University Medical Center in New York City. Dumas and colleagues surveyed women and their pre-adolescent children attending an urban, primary care center in New York City. They asked the subjects about their age, income, heart disease risk factors, and perceptions of their body size using silhouette images that corresponded to specific body mass index (BMI) types — for example, underweight, normal and overweight.

The researchers also recorded participants’ height, weight and BMI, which is a measurement of body weight based on height. A BMI of 25-29 is overweight, and a BMI over 30 is obese.

The researchers found:

• 65.8 percent of the mothers surveyed were overweight or obese.
• 38.9 percent of children surveyed were overweight or obese.
• 81.8 percent of obese women underestimated their weight compared to 42.5 percent of overweight and 13.2 percent of normal weight women; similarly, 86 percent of overweight or obese children underestimated their weight compared to 15 percent of normal weight children.
• Of mothers with overweight or obese children, almost half (47.5 percent) thought their children were of normal weight.
• Children selected larger body images than those chosen by their mothers to describe an “ideal” or “healthy” body image for a woman.
• 41.4 percent of the children in the study thought their moms should lose weight.

“These findings imply that not only is obesity prevalent in urban America, but that those most affected by it are either unaware or underestimate their true weight,” she said. “In addition, obesity has become an acceptable norm in some families. Strategies to overcome the obesity epidemic will need to address this barrier to weight loss.”

Future research should include interventions that study the effect of increased accuracy of body image perception on weight loss among families.

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Co-authors are Robert R Sciacca, Eng.Sc.D.; Jennifer Decolongon, M.D.; Juviza K. Rodriguez, B.A.; and Elsa-Grace V Giardina, M.D.

Author disclosures are on the manuscript. The study was funded by the Department of Health and Human Services and the Arlene and Joseph Taub Foundation.

Note: Actual presentation time is 5 p.m. ET, Wednesday, March 23, 2011.

Statements and conclusions of study authors published in American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect association policy or position. The association makes no representation or warranty as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The association has strict policies to prevent these relationships from influencing the science content. Revenues from pharmaceutical and device corporations are available atwww.americanheart.org/corporatefunding.

Source: American Heart Association