Bone Metabolism in Obesity and Weight Loss

Abstract

Excess body weight due to obesity has traditionally been considered to have a positive effect on bone; however, more recent findings suggest that bone quality is compromised. Both obesity and caloric restriction increase fracture risk and are regulated by endocrine factors and cytokines that have direct and indirect effects on bone and calcium absorption. Weight reduction will decrease bone mass and mineral density, but this varies by the individual’s age, gender, and adiposity. Dietary modifications, exercise, and medications have been shown to attenuate the bone loss associated with weight reduction. Future obesity and weight loss trials would benefit from assessment of key hormones, adipokine and gut peptides that regulate calcium absorption, and bone mineral density and quality by using sensitive techniques in high-risk populations.

Adipocytes regulate the bone marrow microenvironment in a mouse model of obesity

“…Adults with a high BMI have been previously reported to be associated with low BMD (10). Obesity is being increasingly recognized as a negative factor of bone metastasis in humans (11). In this study, high-fat diet mice exhibited high body weights.…”

Does Diet-Induced Weight Loss Lead to Bone Loss in Overweight or Obese Adults? A Systematic Review and Meta-Analysis of Clinical Trials

“…It is important to consider bone turnover markers in this field of research, because the accuracy and precision of DXA is known to decrease with increasing BMI (84) and when participants undergo changes in body weight, (85)(86)(87)(88) and because BMD measured at time points earlier than 6 months are not considered to be clinically significant, given that a complete cycle of bone remodeling takes 4 to 6 months. (53) Thus, diet-induced weight loss induces small but statistically significant losses in total hip BMD that would likely not otherwise be seen in overweight or obese individuals.…”

“…This may be due in part to the greater measurement error that occurs in the lumbar spine in comparison to the hip. (53) DXA scans of the spine, in particular the lumbar region (L 1 -L 5 ), often pick up calcification from other sources besides healthy vertebrae, and this increases apparent BMD readings. (93,94) Such calcification can originate from atherosclerotic lesions within the aorta, or from osteophytes (protrusions of bone tissue that form in response to joint damage from conditions such as arthritis), masking underlying changes in bone mass due to age, disease, or other factors.…”

“…This is because energy restriction induces hormonal changes that might be expected to decrease bone mass, (18,53) and the effects may be more pronounced with severe than with moderate energy restriction. (99) An additional rationale for this hypothesis is that severe energy restriction induces greater weight loss than MER, (100) which would lead to greater mechanical unloading of bone, with subsequently greater bone loss.…”

Obesity and fractures

“…2014;58/5 tion of calcium, vitamin D, proteins and other nutrients during a restriction diet can prevent loss of bone mass, given the heterogeneity of many different studies including only a small number of patients, short time duration and several endpoints (including substitutes as BMD). A concomitant physical exercise program may attenuate bone loss during caloric restriction (44,45); however, no study has adequately analysed the impact of exercise and diet on the incidence of fractures (46).…”