Adolescence Obesity Halts the Natural Increase of Life Expectancy: A Study of 2.16 Million Teenagers

Gilad Twig ^1,2,3 Arnon Afek ^1,4 Ari Shamiss ^1,4 Estela Derazne ^3,4 Landau Rabbi ^3,4 Dorit Tzur ³ Barak Gordon ^3,4 Amir Tirosh ^2,5

¹Department of Medicine, The Chaim Sheba Medical Center, Tel-Hashomer
²The Dr. Pinchas Bornstein Talpiot Medical Leadership Program, The Chaim Sheba Medical Center, Tel-Hashomer
³Medical Corps, The Israel Defense Forces, Tel Aviv
⁴The Sackler School of Medicine, Tel-Aviv University, Tel-Aviv
⁵The Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard School of Public Health, Boston, Massachusetts

Background: The effect of body-mass index (BMI) at adolescence on mortality later in life is unclear.

Methods: Since 1967, measured height and weight of 2,159,327 adolescents (882,792 females and 1,276,535 males, mean age 17.35±0.4 years) were obtained from the Israel Defense Force Registry. Outcome of the study was all-cause mortality before the age of 50 years (between 1967 and 2011).

Results: During 43,126,211 person-year of follow-up 15,469 and 3,061 deaths were recorded among men and women, respectively. As compared with mortality rates observed in the 25^th-50^thpercentiles of BMI (5.59/10⁴and 1.67/10⁴person-year for men and women, respectively), all-cause mortality continuously increased across the BMI range reaching rates of 8.90/10⁴ and 2.90/10⁴-person-year for men and women with BMI>97th percentile, respectively. A multivariate analysis adjusted for socio-economic status, education, and ethnicity demonstrated a significant increase in mortality rates at BMI>50thpercentile (BMI>20.55 kg/m²) for men and ≥85^th percentile in women (BMI>24.78 kg/m²). Increased mortality among overweight and obese adolescents was observed starting at ages 32 and 25 years, respectively. During 4 decades of follow-up, a significant decrease in 20-year mortality rates was documented in normal-weight participants born in 1950-1960 vs. those born at 1970-1980 (4.99/10⁴ vs. 3.60/10⁴ person years), p<0.001). However, no improvement in survival was observed among overweight (95^th>BMI≥85^th; p=0.281) and obese adolescents (BMI≥95^th; 0.426) for at the parallel groups during the same time interval. Formal test of interaction between BMI at adolescence and birth decade was highly significant in multivariate model (p=0.006).

Conclusion: BMI at adolescence, well-within the currently-considered normal range, is a risk factor for all-cause mortality at early adulthood and midlife. As opposed to the observed trends in the entire population, mortality rates among overweight and obese adolescents did not decrease in the last 40 years. Pre-adulthood obesity is expected to attenuate the progressive increase in life expectancy.