London | Being overweight or obese may be associated with an increased risk of premature death, with the greatest effect in men, according to a new study. The risks of coronary heart disease, stroke, respiratory disease and cancer are also all increased, researchers said.
Overall, the excess risk of premature death (before age 70) among those who are overweight or obese is about three times as great in men as in women, they said.
On average, overweight people lose about one year of life expectancy, and moderately obese people lose about three years of life expectancy, said Emanuele Di Angelantonio from University of Cambridge in the UK. We also found that men who were obese were at much higher risk of premature death than obese women. This is consistent with previous observations that obese men have greater insulin resistance, liver fat levels, and diabetes risk than women, said Angelantonio.
The World Health Organisation uses body-mass index (BMI, in kilogrammes per square metre), which relates weight to height, and defines BMI 18.5-25 as normal, 25-30 as overweight, 30-35 as moderately obese, and over 40 as severely obese. For example, for a height of 1.6 metres, overweight is about 60-80 kilogrammes. For a height of 1.8 metres, overweight is about 80-100 kilogrammes. Normal BMI spans a range of similar length below this; moderate obesity spans a range of similar length above.
The study found an increased risk of premature death for people who were underweight, as well as for people classed as overweight. The risk increased steadily and steeply as BMI increased, researchers said. Where the risk of death before age 70 would be 19 per cent and 11 per cent for men and women with a normal BMI, researchers found that it would be 29.5 per cent and 14.6 per cent for moderately obese men and women (BMI 30-35).
This corresponds to an absolute increase of 10.5 per cent for men, and 3.6 per cent for women – three times as big. Researchers defined premature deaths as those at ages 35-69 years. The findings were published in the journal The Lancet.