The study has been published in The American Journal of Epidemiology.
According to Professor Haakon E. Meyer at the Norwegian Institute of Public Health and the University of Oslo, weight increase reduced the risk, whereas weight loss increased the risk.
1 476 men who participated in the Oslo survey in 1972-73 and the Tromso survey in 1974-75 were again studied for, among other things, osteoporosis in the Health Studies in Oslo 2000-01 and Tromso 2001 respectively.
The survey shows that low weight among middle-aged men and subsequent weight loss leads to increased risk of osteoporosis when the men become older.
Almost a third had osteoporosis among the thinnest quarter of men in the 1970s and who later lost weight. In contrast, of the quarter that had the highest weight in the 1970s and had not changed their weight, none of the men had osteoporosis.
Although weight increase and a high weight are beneficial for the skeleton, a stable, healthy weight is still recommended according to Meyer.
With respect to weight loss, however, the impact on osteoporosis and fracture should be taken into account and, if possible, prevented, Meyer says.