Simply being overweight, but not obese, from an early age boosts the risk of premature death by a third - as much as smoking up to 10 cigarettes a day, researchers in Sweden reported on Wednesday. People who are clinically obese by the age of 18 more than double that risk, putting themselves in the same danger zone as long-term heavy smokers of normal weight, they found.
And combining the two factors accumulates the risk: an obese heavy smoker, for example, is nearly five times as likely to die prematurely than a non-smoker who is neither too thin nor too fat. At least a billion people in the world are overweight, and nearly a third of them are obese, according to the World Health Organisation (WHO). Obesity rates have soared over the last three decades, especially among children.
Earlier studies have shown that being excessively fat shortens lifespan and leads to increased rates of chronic disease such as diabetes and arteriosclerosis. But researchers have disagreed sharply up to now on whether being above ideal weight without crossing the line to obesity takes years off one's life.
Nor have previous studies directly compared the impact on mortality of smoking and excess weight. The study designed by Martin Neovius of the Karolinska Institute in Stockholm goes a long way to settling the debate, and shows clearly for the first time that being too heavy can be as dangerous as smoking a couple of packs a day.