Childhood obesity is associated with obesity in adulthood, but it is not known if being overweight in adolescence carries an independent risk for premature death. Addressing this question will help determine if early weight management interventions can reduce obesity-associated mortality. Van Dam and colleagues conducted a prospective cohort study to examine the relationship between body mass index (BMI) at 18 years of age and premature death in women.
The study population included 102,400 predominantly white (90 percent) female nurses who were between 24 and 44 years of age in 1989. Participants were excluded if they had a history of cancer (with the exception of nonmelanoma skin cancer) or if they were pregnant when the study began. They completed a baseline questionnaire about their medical history and health-related variables, including tobacco and alcohol use, contraceptive and hormone therapy, and past (at 18 to 22 years of age) and current physical activity levels.
At the beginning of the study, participants were asked to report what their height and weight were at 18 years of age. Physical examination records of 118 participants were compared to test the reliability of the self-reported information. Although the participants had underestimated their weight at 18 years of age by an average of 3 lb, 1 oz (1.4 kg), there was no relationship between current age and discrepancies in weight recollection. Participants were mailed follow-up questionnaires through July 2001.
BMI was calculated using current height and recalled weight at 18 years of age. Participants were grouped into six categories by their BMI at 18 years of age: less than 18.5 (kg per m2), 18.5 to 21.9, 22.0 to 24.9, 25.0 to 29.9, 30.0 to 34.9, and greater than 35.0. Mortality rates were calculated for each BMI category.
During follow-up, death information was obtained from family members, postal authorities, and the National Death Index. Overall, 710 patients died. The risk of death during the study was associated with an increased BMI at 18 years of age. Participants with a BMI of 25.0 to 29.9 were 1.66 times as likely to die as participants with a BMI of 18.5 to 21.9. However, participants with a BMI of more than 30 were 2.78 times more likely to die compared with their counterparts. Although women with higher BMIs at 18 years of age were more likely to be overweight as adults, this association did not fully explain the observed mortality differences. Additionally, controlling for smoking status and other health-related variables did not change the overall results.
The authors conclude that being overweight at 18 years of age increases the risk of premature death in women, an increase that is independent of their adult weight or lifestyle factors. However, the study did not evaluate information on causes of death, leaving the reasons for increased mortality unclear. Given these findings, the authors recommend that physicians emphasize the primary prevention of overweight in children and adolescents.