Wednesday, December 21, 2005

Fat and Happy, Maybe Not Dumb

American Journal of Epidemiology 2006 163(1):1-8;

Original Contribution

Association of Body Mass Index with Suicide Mortality: A Prospective Cohort Study of More than One Million Men

Patrik K. E. Magnusson1, Finn Rasmussen2,3, Debbie A. Lawlor4, Per Tynelius2,3 and David Gunnell4

1 Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden
2 Child and Adolescent Public Health Epidemiology Group, Department of Public Health Sciences, Karolinska Institute, Stockholm, Sweden
3 Division of Epidemiology, Stockholm Centre of Public Health, Stockholm, Sweden
4 Department of Social Medicine, University of Bristol, Bristol, United Kingdom

Correspondence to Dr. Finn Rasmussen, Child and Adolescent Public Health Epidemiology Group, Department of Public Health Sciences, Karolinska Institute, Norrbacka, SE-171 76 Stockholm, Sweden (e-mail:

The authors investigated the association of body mass index (BMI) with suicide in a record linkage study based on the Swedish Military Service Conscription Register, the Population and Housing Censuses, and the Cause of Death Register. The cohort studied consisted of 1,299,177 Swedish men who were conscripted in 1968–1999, had their BMI measured at age 18–19 years, and were followed up for as long as 31 years. A strong inverse association was found between BMI and suicide. For each 5-kg/m2 increase in BMI, the risk of suicide decreased by 15% (95% confidence interval: 9, 21). The association was similar when subjects with mental disorder at baseline were excluded from the analysis. BMI-suicide associations were similar in relation to suicide deaths occurring in the first 5 years of follow-up (hazard ratio for each 5-kg/m2 increase in BMI = 0.84, 95% confidence interval: 0.73, 0.96) compared with associations ≥10 years after baseline (hazard ratio = 0.87, 95% confidence interval: 0.79, 0.96), indicating that weight loss as a consequence of mental illness does not explain the BMI-suicide association and that factors influencing BMI may be causally implicated in the etiology of mental disorders leading to suicide.


Brooklyn Dodger Comments: The Dodger's current framework on "personal" health is that stress causes mental illness causes risk behavior causes overweight, smoking, excessive drinking, bad driving, causes illness and death. Therefore, reading the title on medline, the Dodger thought for sure that obesity would be associated with suicide. To the Dodger's surprise, the conclusions went the other way.

Now to commentary on the paper. First, these are Swedes, thought to be gloomy and frequent suicide victims. Something for the Dodger to look up in the future.

Second, why did the authors and reviewers neglect to state the main outcome in the abstract? From the full text the Dodger gleaned: "1,299,177 men ... were included in this analysis.
Up to the end of 1999, a total of 3,075 (0.24 percent) died ... by suicide—the suicide rate measured from conscription was 16.2 per 100,000 per year."

Third, the only stratum signficantly worse that normal weight was underweight (bmi <>
Since these BMI strata are arbitrary, the range of normal might be gerrymandered to make the benefits of "overweight" go away. For a 6-foot person, the upper boundry of underweight is 136 pounds, which is seriously thin. The upper bound of normal is 185 pounds, which is not seriously chubby.

Maybe the lower bmi stratum is poor in drinkers, and therefore at higher risk because of that?

Maybe the important finding is that obesity is not associated with increased suicide risk, and therefore whatever causes obsesity, or excessive eating, is not associated with increased suicide risk?

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