The Impact of Interventional Weight Loss on Bone Marrow Adipose Tissue in People Living with Obesity and Its Connection to Bone Metabolism

Abstract

This review focuses on providing physicians with insights into the complex relationship between bone marrow adipose tissue (BMAT) and bone health, in the context of weight loss through caloric restriction or metabolic and bariatric surgery (MBS), in people living with obesity (PwO). We summarize the complex relationship between BMAT and bone health, provide an overview of noninvasive imaging techniques to quantify human BMAT, and discuss clinical studies measuring BMAT in PwO before and after weight loss. The relationship between BMAT and bone is subject to variations based on factors such as age, sex, menopausal status, skeletal sites, nutritional status, and metabolic conditions. The Bone Marrow Adiposity Society (BMAS) recommends standardizing imaging protocols to increase comparability across studies and sites, they have identified both water–fat imaging (WFI) and spectroscopy (1H-MRS) as accepted standards for in vivo quantification of BMAT. Clinical studies measuring BMAT in PwO are limited and have shown contradictory results. However, BMAT tends to be higher in patients with the highest visceral adiposity, and inverse associations between BMAT and bone mineral density (BMD) have been consistently found in PwO. Furthermore, BMAT levels tend to decrease after caloric restriction-induced weight loss. Although weight loss was associated with overall fat loss, a reduction in BMAT did not always follow the changes in fat volume in other tissues. The effects of MBS on BMAT are not consistent among the studies, which is at least partly related to the differences in the study population, skeletal site, and duration of the follow-up. Overall, gastric bypass appears to decrease BMAT, particularly in patients with diabetes and postmenopausal women, whereas sleeve gastrectomy appears to increase BMAT. More research is necessary to evaluate changes in BMAT and its connection to bone metabolism, either in PwO or in cases of weight loss through caloric restriction or MBS, to better understand the role of BMAT in this context and determine the local or systemic factors involved.

Associations of gestational diabetes and proton density fat fraction of vertebral bone marrow and paraspinal musculature in premenopausal women

“…Our study participants did not show significant discrepancies in steps per day between the GDM group and the control group, however, excluding the impact of physical activity is difficult. We suggest that steps per day can be both the cause and the consequence of the changes in bone and muscle tissue, because the fat-infiltrated bones and muscles can alter the microenvironment, compromising function and performance ( 21 , 22 , 45 , 46 ). In this regard, physical activity levels can be influenced both by a history of GDM and by fat infiltrations in bones and muscles, as reflected in higher PDFFs.…”

Exploring the Interplay between Bone Marrow Stem Cells and Obesity

“…The connection between BMAT and bone homeostasis has been thoroughly studied using animal models [ 88 , 89 , 90 , 91 ]. In models of obesity generated by diet, BMAT constantly expands [ 75 , 78 , 92 , 93 ].…”

“…Because people living with obesity (PwO) exhibit normal or even higher BMD due to mechanical adaptations to increased body weight, obesity has long been considered to be a preventive factor against osteoporosis [ 95 ]. Nevertheless, this assumption has been contested by several studies [ 88 , 96 , 97 ]. PwO have deficiencies in the quality of their bone matrix and structure, lower levels of bone remodeling, and increased fracture risk in unique skeletal locations (proximal humerus, ankle, and upper leg).…”

“…PwO have deficiencies in the quality of their bone matrix and structure, lower levels of bone remodeling, and increased fracture risk in unique skeletal locations (proximal humerus, ankle, and upper leg). Hormonal imbalances associated with elevated (central) obesity and chronic inflammation are mostly responsible for these latter effects on bone metabolism [ 88 , 96 ]. There are not many clinical studies assessing BMAT in PwO and its relationship with bone metabolism, but it is possible that BMAT plays a role in some of the worsening components linked to bone quality deterioration in obesity [ 88 ].…”

“…Hormonal imbalances associated with elevated (central) obesity and chronic inflammation are mostly responsible for these latter effects on bone metabolism [ 88 , 96 ]. There are not many clinical studies assessing BMAT in PwO and its relationship with bone metabolism, but it is possible that BMAT plays a role in some of the worsening components linked to bone quality deterioration in obesity [ 88 ]. Cohen et al assessed bone micro-architecture, remodeling, and BMAT in healthy premenopausal women of different weight ranges using histomorphometry in labeled transiliac bone samples [ 98 , 99 ].…”