Contrary to what was previously assumed, overweight is not increasing the overall death rate in the German population. Matthias Lenz of the Faculty of Mathematics, Computer Science, and Natural Sciences of the University of Hamburg and his co-authors present these and other results in the current issue of Deutsches Ärtzeblatt International (Dtsch Artzebl Int 2009; 106: 641).
Most Germans are overweight, with a body mass index (BMI) between 25 and 29.9 kg/m2. About 20% are obese (BMI of 30 or over), with age- and gender-related differences. The authors systematically evaluated 42 studies of the relationships between weight, life expectancy, and disease.
The Süddeutsche Zeitung published an advance notice of the report (http://www.sueddeutsche.de/gesundheit/140/489526/text/), which shows that overweight does not increase death rates, although obesity does increase them by 20%. As people grow older, obesity makes less and less difference.
For coronary heart disease, overweight increases risk by about 20% and obesity increases it by about 50%. On the other hand, a larger BMI is associated with a lower risk of bone and hip fracture.
In relation to cancer, the overall death rate among extremely obese men (BMI above 40) is no higher than among those of normal weight. Men who are overweight even have a 7% lower death rate. No significant association was found in women.
According to the authors' analysis, overall mortality is unchanged by overweight, but increased by 20% by obesity, while extreme obesity raises it by up to 200%.