Experts advise slimming down despite surprising results

By Amanda Gardner
HealthScoutNews Reporter



TUESDAY, April 1, 2003 (HealthScoutNews) -- Could there be a silver lining to all that fat Americans have been accumulating lately?

Much to their surprise, scientists at Duke University Medical Center have found that overweight and obese individuals actually have better survival rates for one year following a heart attack than normal-weight people.

Not so surprisingly, the researchers also determined the United States had the highest combined rate of obese and very obese people, while Asia had the highest percentage of normal-weight people.

The Duke team presented the findings April 1 at the American College of Cardiology's scientific sessions in Chicago.

One of the ironies in these findings, of course, is that being heavy is a risk factor for coronary artery disease, and may have been what helped land these patients in the hospital in the first place.

"We know that obesity is related to the development of coronary disease, so it's a risk factor. But for whatever reason, in this population, it doesn't seem to be associated with [poor] outcomes over the 90-day to one-year period," says Dr. Kristin Newby, co-author of the study and an associate professor of medicine at Duke University Medical Center. "The process of obesity as a risk factor for the development of coronary disease may be different than the way obesity affects short-term outcomes."

Newby and her colleagues had initially hypothesized that overweight and obese people would have higher mortality rates in the intermediate term.

To test the hypothesis, the researchers looked at data already collected for two related international trials and divided the 15,904 participants into four groups based on their body mass index (BMI): normal (BMI of 18.5 to 25), overweight (25 to 29.9), obese (30 to 34.9) and very obese (more than 35).

The results came as somewhat of a surprise to researchers used to equating overweight with poor health outcomes. One year after a heart attack, individuals in the obese grouping had the lowest death rate (2.2 percent), followed by those were classified as very obese (2.6 percent), overweight (2.7 percent mortality) and, finally, normal individuals bringing up the rear (4.3 percent).

Normal-weight participants also had the highest death rate after 90 days (2.6 percent) compared with overweight participants (1.6 percent), very obese participants (1.4 percent) and obese participants (1.3 percent).

A similar pattern was evident at 30 days, with normal weight individuals demonstrating a death rate of 1.7 percent, very obese individuals (1.2 percent), overweight individuals (1 percent), and obese individuals (0.9 percent).

The results may actually have more to do with the age of the people studied than their girth. "Youth hides a lot of sins," says Dr. Terrence Sacchi, chief of cardiology at Long Island University Hospital in New York City. "It seems that the patients in the overweight and obese group were younger, and also they were treated more aggressively."

"The findings still held up when adjusted in overweight and obese people, but not in the very obese group," says Eric Eisenstein, Newby's co-author and an assistant research professor in management at the Duke Clinical Research Institute. "Even after adjusting for all those factors, we still found that at one year the overweight and obese groups had a lower hazard of death than the normal people and the very obese people."

One thing to keep in mind is that this study looked only at intermediate-term survival, not long-term survival. "I don't think anyone is advocating remaining obese," Sacchi says. "It is associated with multiple risk factors."

Dr. Albert Chan, associate director of the catheterization laboratory at the Ochsner Clinic Foundation in New Orleans, says there may also be bias because the authors got their data from two different studies, which recruited people from different countries.

"What we don't want to come out of this is that we think weight control is a bad thing," Newby adds. "We don't understand these findings and we have a lot of work to do, but that doesn't mean that control of weight is not what we should be striving for. We only know out to about a year. There may be something that just happens in very short term, but over the long term there are still all the complications that come with obesity."

That means the United States is still in pretty bad shape when it comes to these risk factors. The study authors discovered this country had the highest rates of obese (24 percent) and very obese (13 percent) people and the lowest rates of normal (22 percent) people. Asia had the highest rate of normal-weight individuals (58 percent), Western Europe came next (31 percent), followed by Eastern Europe (29 percent), Latin America (28 percent), Australia/New Zealand (26 percent), and Canada (23 percent).

Australia/New Zealand and Canada tied for second place in the "very obese" category (7 percent each), followed by Latin America (6 percent), Eastern and Western Europe (4 percent each), and Asia (1 percent).


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Now I'm curious to know the outcome %'s for UNDERweight persons, who don't seem to be represented in this report.

Doreen

Hmmm ... according to the Duke Med News report
http://dukemednews.duke.edu/news/article.php?id=6478

Not meaning to discount the dangers of being fat -- after all, I am trying to lose weight and I know my weight is a danger to my health -- but it struck me as somewhat strange that the study defines "normal" as a category that a minority of people falls into. I think they need a new term to refer to that category.

Good point, Liz! I never thought of it that way. Perhaps "healthy" or "physically fit"? I see you are a researcher so maybe you can come up with more reasonable term......

Kay

Also, they used BMI to group people. So IMHO that makes their whole study worthless. If they'd used body fat, or performance on fitness trials, the study might have actually been useful. Oh well!

I agree that BMI isn't an accurate gauge for fatness/obesity. Nonetheless, I still think the findings from this study are interesting and shouldn't be discounted. It seems to fly in the face of current thinking that thin is better when it comes to heart attack survival. As a nurse who worked in cardiac care for years, I can tell you that patients are systematically told to lose weight and receive diet counselling (low fat of course ) as part of their cardiac rehabilation.

Doreen

Overweight people are still more likely to have heart attacks. This study did not address that, just survival after a heart attack. From everything I have seen, losing weight is a good idea to prevent future heart attacks.

It could be that heart attacks in overweight people have different causes than in non-overweight people and therefore the survival rates may be different. For example, non-overweight people may have a lot more blockage of their arteries than overweight people before they have a heart attack. This could mean that the consequences of a heart attack are more serious for non-overweight people, because something in their thinness protects them from having a heart attack until the situation in their arteries is really serious. I have no data to support that hypothesis -- it is just a hypothesis -- but as someone noted I am a researcher and I can tell you that knowing something is related to something else doesn't mean that one causes the other (in somewhat technical language, correlation is not the same thing as causation).

It's like saying that people who are overweight are more likely to be diabetic. That's true, but it doesn't mean that being overweight causes diabetes. It could be that hyperinsulinemia causes both diabetes and weight gain.

Also, while BMI isn't an accurate gauge of fatness/obesity in any one person, I think it is pretty good across the population, and this study presented results for groups, not for individuals. I think we can be assured that the group with a high BMI was, on average, fatter than the group with a low BMI, although there may be individual exceptions in each group.

My husband's grandmother's husband (got that?) had a heart attack 2 1/2 weeks ago, then a second attack in the hospital the next day. He is home now, recuperating, has lost 20 pounds in the process. He is a big man, about 6' 2" or so and I don't remember what he said he weighed then and now, just the difference of 20 lbs, but only had a bit of a belly. He's in his early 70's.

The interesting thing is that his heart doctor is telling him to eat a low carb diet. This WOE is making progress, even here in Kansas.

Sharon

Don't get me wrong, as a hypothesis, I think it's fascinating. I do agree with everything you all have said. I just get very frustrated with studies that spend a great deal of time and money yet do not seem to be very well focused or well designed. (I admit that I haven't read the studies themselves so my concerns may well be the result of a poorly written article and not the study itself.) My problem is that it seems like the statistical significance of the results is dependent on measurements (like BMI) that I just don't think are valuable/valid enough on their own to be both relevant and significant.

I wish I could find the actual studies this article is based on, but I don't really feel up to searching for them tonight. As you said, Liz, correlation does not equal causation. And I don't feel like they have shown that they eliminated enough other variables (like BF% or fitness levels or fat distribution or any of a million other things) such that the BMI stuff would be valuable in and of itself. So I'm kinda left wondering, what's the point? At least they say they're going to do further research. I do hope it eventually leads to good things, I just want the good science sooner!

Please excuse my cynical rambling, did not have a good day and I'm tired.