Impacts of body mass index, physical activity, and smoking on femoral bone loss. The Tromsø Study

Journal of Bone and Mineral Research,

Emaus N, et al. – Bone mineral density (BMD) is a reflection of bone strength and lifestyles that preserve bone mass may reduce fracture risk in old age. In the prevention of osteoporosis and fracture risk, the effect of combined lifestyles through adult life should be highlighted.


  • This study examined the effect of combined profiles of smoking, physical activity and body mass index (BMI) on lifetime bone loss.
  • Data was collected from the population-based Tromsø Study.
  • BMD was measured as g/cm2 by DXA (GE Lunar Prodigy) at the total hip and femoral neck in 2580 women and 2084 men aged 30–80 years in the 2001/02 survey, and repeated in 1401 women and 1113 men in the 2007/08 survey.
  • Height and weight were measured and lifestyle information was collected through questionnaires.
  • Data was analyzed using linear mixed models with second-degree fractional polynomials.


  • From peak at the age around 40 years to 80 years of age, loss rates varied between 4% at the total hip and 14% at femoral neck in nonsmoking, physically active men with a BMI of 30 kg/m2 to approximately 30% at both femoral sites in heavy smoking, physically inactive men with a BMI value of 18 kg/m2.
  • In women also, loss rates of more than 30%, were estimated in the lifestyle groups with a BMI value of 18 kg/m2.
  • BMI had the strongest effect on BMD, especially in the oldest age groups, but a BMI above 30 kg/m2 did not exert any additional effect compared to the population average BMI of 27 kg/m2.
  • At the age of 80 years, a lifestyle of moderate BMI to light overweight, smoking avoidance and physical activity of 4 hours vigorous activity per week through adult life may result in 1–2 standard deviations higher BMD levels compared to a lifestyle marked by heavy smoking, inactivity and low weight.

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