The prevalence of obesity is escalating yearly, with diet-induced weight loss considered the primary treatment option. However, some but not all recent studies have alluded to the possibility that diet-induced weight loss has a harmful effect on bone mineral density (BMD), which could increase the risk of osteoporotic fractures.
A systematic review and meta-analysis was conducted to quantify the effect of diet-induced weight lRMMoss on BMD. Data on 40 dietary interventions, from 28 studies on healthy overweight/obese adults undergoing a diet-induced weight loss regime examining BMD at the hip, spine or total body via dual energy x-ray absorptiometry were included. A random effects model was used to examine the effect of the duration of the intervention on both weight and BMD.
Body weight decreased significantly irrespective of the length of the dietary intervention. There was a significant decrease in hip BMD with dietary interventions of 6-month (p=0.000, n = 6 interventions) and 24 month (p= 0.047) duration. Three of the studies that used a 6-month dietary intervention also measured BMD at 12 months from baseline. In these 3 studies, hip BMD was significantly decreased at 6 months (p=0.000), and the decrease from baseline remained also at 12 months (p=0.050). When BMD was investigated in the lumbar spine and the total body, no significant changes in BMD occurred following dietary interventions ranging from 3 to 24 months’ duration.
This meta analysis has shown that loss of BMD in the hip – but not in the spine or total body – occurs in response to diet-induced weight loss in overweight and obese individuals. More investigation needs to be conducted to determine the long-term effects that diet-induced weight loss may have on bone and fracture risk.