A recent study (G Twig et al. NEJM 2016; 374: 2430-40) which had more than 42 million person-years of followup (1967-2010) showed that adolescents with a BMI in the 50th to 74th percentile (CDC values), well within the accepted normal range, had increased cardiovascular and all-cause mortality.
The study involved more than 2.3 million Israeli adolescents with up to 40 years of followup information. The study utilized data obtained from 17 year olds who were seen 1 year prior to mandatory military service. There was increasing mortality associated with higher BMI subgroups.
- For those between the 50-74% in adolescence: the hazard ratios for coronary heart disease 1.49, for stroke 1.18, and total cardiovascular causes was 1.32.
- For those ≥95% (obese) in adolescence: the hazard ratios for coronary heart disease 4.89, for stroke 2.64, and total cardiovascular causes was 3.46.
My take: this study shows that even modest increases in BMI are associated with modest increase in cardiovascular mortality over 40 years. Whether the BMI itself plays a causal role or is more of an epiphenomenon of other risk factors (eg. sedentary risk factors) is not clear.