Teenagers with a high body mass index (BMI) are at greater risk of early death, says a new study by a team of researchers.
In the recent decades, the number of overweight and obese teenagers has increased. One in three adolescent population in the UK and US are considered overweight and obese. Obesity in early life is considered a risk factor for cardiovascular disease and all causes in adulthood.
‘The higher a teenager's BMI, the greater their risk of early death from heart disease is in adulthood. But, the new study has found even those teenagers with a 'normal' BMI are at greater risk.’
But the surprising fact is that those teenagers with a BMI of 20 - considered to be well within the normal range - are at heightened risk of fatal heart attack or stroke.
The new study aimed to determine the BMI threshold that is linked to increased risk of early death. BMI is a calculation of a person's weight in kilograms divided by the square of their height in meters. The result quantifies a person as being underweight, normal weight, overweight or obese.
Researchers from the Hebrew University of Jerusalem assessed the BMI of 2.3 million Israeli 17-year-olds from 1967 to 2010. The researchers studied the link between BMI in late adolescence and death from heart disease, stroke and sudden death in adulthood by mid-2011.
The researchers noted 2,918 of 32,127 deaths (9.1%) were from cardiovascular causes, including 1,497 from coronary heart disease, 528 from stroke and 893 from sudden death.
The findings of the study showed a rise in the risk of cardiovascular death in the group that was considered within the 'accepted normal' range of BMI. The increased risk of death from coronary heart disease was found in those with BMI values above 20.
Adolescents with a BMI that was considered 'normal' between the range of 18.5 to 24.9 were at an increased risk of early cardiovascular and all-cause mortality during the 40 years follow-up. The higher the BMI, adolescent obesity was linked with an even greater risk of early death.
The researchers gave two explanations for how adolescent BMI influences cardiovascular outcomes in adults.
Firstly, overweight and obesity during teenage years are harmful because it is linked with unfavorable metabolic conditions, including high blood pressure, impaired ability to break down glucose, insulin resistance and the formation of plaques in key blood vessels.
Secondly, BMI tends to 'track' along the life course so that overweight teenagers tend to become overweight adults.
Professor Jeremy Kark of the Hebrew University, said, "Our findings appear to provide a link between the trends in adolescent overweight during the past decades and coronary mortality in midlife."
"The continuing increase in adolescent BMI, and the rising prevalence of overweight and obesity among adolescents may account for a substantial and growing future burden of cardiovascular disease, particularly coronary heart disease."
Their study appears in the New England Journal of Medicine.