A study involving 37,000 Israeli teenagers over a 17-year period found that an elevated body mass index (BMI) at adolescence and at adulthood are independently associated with the risk of coronary heart disease and diabetes.

BMI – a person’s weight in kilograms divided by the squared height in meters — has long been known to show an increased risk of diabetes close to diagnosis in adulthood, around age 30 to 45. A BMI of 25 or more is considered overweight while 30 BMI or higher is considered obese. But the study showed that even an elevated BMI in normal range puts one at risk of heart disease.

The study of incoming Israeli Defense Forces (IDF) career personnel, published in the New England Journal of Medicine on April 7, 2011, focused on this rarely studied age group.

The joint research team was led by Dr. Amir Tirosh of Sheba Tel-Hashomer’s Talpiot Medical Leadership Program; Brigham and Women’s Hospital and Harvard Medical School researcher Dr. Iris Shai; and Dr. Assaf Rudich of Ben-Gurion University (BGU) and the university’s National Institute of Biotechnology in the Negev.

Researchers from the IDF Medical Corps and Tel Hashomer Hospital recorded the BMI of participants at 17 and again periodically over the next 17 years. For diabetes, BMI at age 17 predicted the risk mainly since it is associated with BMI later in life. However, for heart disease, BMI at adolescence as well as BMI at adulthood — independently of each other — predicted the risk of the disease. During the study period, 1,173 new cases of diabetes and 327 new cases of heart disease were diagnosed.

“Our results suggest that the obesity problem in children and teens is likely just the tip of an iceberg for increased risk for the occurrence of Type 2 diabetes and heart disease in your 30s and 40s,” said Tirosh. “While this is an observational study, it does suggest that an adolescent with a relatively high BMI, who grows up to become a lean adult, practically eliminated the added risk of developing diabetes attributed to his BMI at adolescence.

“Conversely, the risk of that person for heart disease will remain elevated compared to the lean teen who became a lean adult, though still will be lower than that of the heavier teen who became an obese adult.”

He suggested that for effective prevention of early occurrence of heart disease in adulthood, very early intervention to promote healthy lifestyle habits seems essential.

BGU recently published a series of intervention studies showing that nutritional habit modification can not only halt, but even reverse, the progression of atherosclerosis, the underlying process of heart disease.