Significant reductions in total-body bone mineral density (BMD) have b
een reported in obese women who consume very-low-calorie diets. A redu
ction in bone mass is highly correlated with an increased risk of oste
oporosis. The present study investigated whether strength training wou
ld prevent such reductions in dieters. Twenty-one healthy obese women
weighing (mean +/- SD) 91.1 +/- 9 kg and aged 38 +/- 9 years were rand
omly assigned to receive either diet alone or diet plus resistance tra
ining. Both groups consumed a 925-kcal/d portion-controlled diet for t
he first 16 of 17 weeks and a 1,000 to 1,500-kcal/d balanced deficit d
iet thereafter. Bone mineral content (BMC), BMD, fat-free mass (FFM),
and fat mass were measured with dual-energy x-ray absorptiometry (DEXA
) before and after 24 weeks of dieting. No significant changes in tota
l-body or lumbar spine BMC and BMD were observed in either condition a
t the end of treatment. However, both groups demonstrated a significan
t loss of both BMC and BMD in the femoral neck and greater trochanter.
Diet plus resistance training was not associated with a significantly
better outcome on either of these measures versus diet alone. The res
ults suggest that increasing the energy content of very-low-calorie di
ets to 925 kcal/d may prevent the loss of total BMD, but not the loss
from the femoral neck and greater trochanter. These findings raise a c
oncern in light of the high frequency of dieting in American women. Co
pyright (C) 1997 by W.B. Saunders Company.