Older Women who are Overweight or Obese Have Vertebral Abnormalities, Partially Degraded TBS, and BMD that Worsen with Weight Loss

Obesity is a risk factor for chronic diseases and moderate weight loss is generally recommended. Energy restriction results in the loss of hip bone mineral density (BMD) in older adults, but there is no consistent decline at the lumbar spine (LS), possibly due to vertebral abnormalities although this may also be dependent on the amount of weight loss. In this secondary analysis of weight loss trials investigating BMD and trabecular bone score (TBS) changes over 12–18 months, 92 postmenopausal women (60.8 ± 5.8 years; body mass index 32.7 ± 4.4 kg/m²) without osteoporosis, were divided into two groups: those who lost < 5% body weight (minimal) or ≥ 5% (moderate). Hip and LS–BMD and TBS were measured at baseline, 6 and 12–18 months. Exclusion of vertebral abnormalities (VE) was used to calculate BMD at the spine (LS–BMD–VE) using standard guidelines. Women lost 2.3 ± 2.4% and 8.5 ± 4.7% weight in the minimal and moderate weight loss groups, respectively. Over one third of the women had at least one vertebral abnormality or partially degraded TBS at baseline that worsened after weight loss, increasing to over 50% in this population (p < 0.05). TBS and hip BMD decreased with weight loss (p < 0.05), but LS–BMD did not decrease significantly. However, after excluding vertebral abnormalities, the LS–BMD–VE decreased in the entire population (p < 0.01), and by 1.7 ± 4.3% in the moderate weight loss group. This study suggests that older women without osteoporosis have vertebral abnormalities that obfuscated declines in BMD with weight loss, indicating that bone at the spine is further compromised.