Boston: Overweight teeenagers have a greater risk of early death, a new US study from the Harvard School of Public Health has found.

Teenagers who are obesity threatens their health are three times more likely to die early than peers of a normal weight. Obesity also raises the risk of heart disease, diabetes and several types of cancer – including bowel, kidney, oesophageal and stomach cancers – as well as womb and breast cancer in post-menopausal women.

Women who are overweight at 18 are 66 per cent more likely to die prematurely than those who are thin.

Obesity at 18, however, nearly triples the risk of dying by middleage, according to the US study, published in the Annals of Internal Medicine, and are likely contributed to long-terms effects on the cardiovascular system that led to early death.

Researchers looked at the medical records of 100,000 women. But the doctors conclude that the results may well apply to men.

Their findings revealed that those who were overweight or obese at 18 faced a higher risk of early death from heart disease, cancer, suicide and other causes just 12 years later.

The definition of being overweight or obese was measured according to the body mass index. BMI is an individual’s weight in kilos divided by the square of their height in metres.

Under 18.5 is classed as underweight, 18.5 to 25 is healthy, 25 to 30 is overweight, 30 to 35 is obese and over 35 very obese.

The medical records come from the long-running Nurses’ Health Study II, which began following 116,671 female nurses in 1989, when the women were aged between 24 and 44. Over the next 12 years 710 women died, with an increase in risk climbing in tandem with their weight at 18.