Depression Support Journal

(The New York Times News Service) -- Overweight people appear to be the least likely to kill themselves, a new Swedish study suggests.

The researchers tracked 1.3 million male military recruits for as long as 31 years, and found that the risk of suicide was highest among those who were the skinniest.

However, two American suicide specialists question the unusual findings, and both suspect that psychiatric disorders may have played a role in the higher suicide rates seen in the study.

"Undiagnosed, untreated or undertreated mental illness is the most probable explanation here," says M. David Rudd, chairman of the Department of Psychology at Texas Tech University.

There hasn't been much research into a possible link between body weight and suicide. People who try to kill themselves have often gained or lost weight, "but it's viewed as secondary to the diagnosed mental disorder," Rudd notes.

In the new study, researchers analyzed medical records of Swedish men who were conscripted into military service from 1968 to 1999.

They found that suicide rates were related to weight as measured by body mass index: a ratio of height to weight.

As body mass indexes went up, the suicide rates went down by 15 percent increments, the researchers said. The study authors said the link held up even when they removed recruits who had mental problems when they were first conscripted at age 18 or 19.

The findings appear in the Jan. 1 issue of The American Journal of Epidemiology.

But there might be more mental illness at work here than the Swedish researchers considered, says Thomas Joiner, a professor of psychology at Florida State University and author of the book, "Why People Die by Suicide." He suspects that some of the young men who later committed suicide might have suffered from undiagnosed psychological disorders at the time of their recruitment. Their illnesses, in turn, could have caused low weight -- often a symptom of depression.

"The (study) authors attempt to argue that this is not the explanation, but I don't think they have adequately ruled it out," Joiner says.

Another "far more speculative link," he says, is that people with appetite problems and people who commit suicide may share problems with serotonin, a brain chemical that helps regulate emotions.

Regardless of whether there's a link between body weight and suicide, Rudd says there can be cause for concern when someone slims down or fattens up -- often quickly or dramatically. Weight fluctuations are frequently the sign of a mental or physical illness, he notes.

Copyright 2005 The New York Times News Service. All rights reserved.

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