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

Male? Obese? Twice as likely to die early

Study finds lifelong doubling in death risk for men who are obese at age 20 years

Stockholm, Sweden: Men who enter adult life obese face a life-long doubling of the risk of dying prematurely, new research has found.

In a study presented today (Tuesday) at the International Congress on Obesity in Stockholm, researchers tracked more than 5,000 military conscripts starting at the age of 20 until up to the age of 80. They found that at any given age, an obese man was twice as likely to die as a man who was not obese and that obesity at age 20 years had a constant effect on death up to 60 years later. They also found that the chance of dying early increased by 10% for each BMI point above the threshold for a healthy weight and that this persisted throughout life, with the obese dying about eight years earlier than the non-obese.

“As the obesity epidemic is still progressing rapidly, especially among children and adolescents, it is important to find out if obesity in early adulthood has lifelong mortality effects,” said the study’s leader, Esther Zimmermann, a researcher at the Institute of Preventive Medicine, Copenhagen University Hospital and the Institute of Biomedical Sciences at University of Copenhagen in Denmark. “Previous studies have investigated obesity and mortality in middle-aged populations, which only tells us about the detrimental effects of obesity in middle age. Our study sheds light on how obesity at age 20 years affects obesity throughout adult life. It is the first study with such a long follow-up time and thus the first study to investigate the lifelong effect.”

In the study, the researchers compared mortality in a sample of 1,930 obese male military conscripts with that in a random sample of 3,601 non-obese male conscripts. Body mass index (BMI) was measured at the average ages of 20, 35 and 46 years, and the researchers investigated that in relation to death in the next follow-up period. A total of 1,191 men had died during the follow-up period of up to 60 years. The results were adjusted to eliminate any influence on the findings from year of birth, education and smoking.

“At age 70 years, 70% of the men in the comparison group and 50% of those in the obese group were still alive and we estimated that from middle age, the obese were likely to die eight years earlier than those in the comparison group,” Zimmermann said. The researchers also investigated the effect of the broad BMI range on mortality from the age of 20 and found the lowest death risk in the men who had a BMI of 25. Underweight men had a slightly elevated risk, and the risk of early death crept up steadily by 10% for each BMI unit above 25 for those men who were overweight or obese.

Zimmermann said it is unclear whether it is being obese at age 20 that conferred the men’s increased death risk or whether the lifelong effect is due to obesity often being a lifelong condition for them. She said more research is warranted to find the answer to that question.

“More than 70% of the obese young men were still obese at the follow-up examinations, whereas only 4% of the men in comparison group developed obesity during follow-up. Obesity seems to be a persistent condition and it appears that if it has not occurred in men by the age of 20, the chance of it developing later are quite low. The persistence of obesity may partly explain why obesity at 20 years of age has lifelong mortality effects, but it needs to be proven whether that is the full explanation or whether, by itself, being obese at an early age increases the risk of early death,” she said.

Zimmermann said her group plans to study the patterns of ill health that caused the early death in the obese group, in order to determine whether the same diseases are causing death at different ages. Such information may shed some light on the mechanisms through which obesity works at different ages, she said.

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Her study was funded by grants from the Cluster for Endocrinology and Metabolism, University of Copenhagen, Denmark.

Source: International Association for the Study of Obesity