Bariatric Surgery and Bone Loss: Do We Need to Be Concerned?

Abstract

Despite significant improvement in weight and comorbid conditions, there is growing evidence that bariatric surgery may exert a negative effect on the skeleton. This review has focused on the impact of bariatric surgery on bone health, with the concern that bariatric surgery may increase skeletal fragility and fracture risk by accelerating bone loss. We have highlighted studies evaluating changes in bone metabolism after three commonly performed bariatric procedures including laparoscopic adjustable gastric banding, Roux-en-Y gastric bypass surgery and increasingly popular sleeve gastrectomy. This review has also discussed some of the technical issues faced in measuring bone in obese populations and during dynamic weight loss. There is limited evidence regarding potential mechanisms for the reported observations of increased bone turnover and/or bone loss after bariatric surgery. We have reviewed the evidence surrounding potential factors affecting bone health in bariatric patients such as rapid weight loss per se, nutritional deficiencies, effects of fat-derived adipokines and gut-derived appetite-regulatory hormones. Future prospective long-term cohort studies are needed to define how to quantify bone loss in individuals with obesity, particularly following massive weight loss, and for how long the bone changes continue. These studies will help clarify any negative clinical consequences of these changes, including future fracture risk in this unique group of patients. IntroductionThe prevalence of obesity worldwide has increased significantly in recent decades because of a complex range of environmental and possibly also epigenetic factors. Obesity is associated with increased mortality [1] with reduced life expectancy, especially amongst people affected from young adulthood [2], as well as multiple comorbidities including type 2 diabetes, hyperlipidemia, sleep apnoea, malignancy and decreased quality of life [3].The medical management of obesity is limited by the variable, limited response to treatment, suboptimal compliance and adverse effects of antiobesity medications. At present, the only effective, long-term treatment for obesity remains bariatric surgery, which results in substantial and sustained weight loss, significant reductions in comorbid conditions, and prolonged longevity [4]. In fact, the utilization of bariatric surgery as a therapeutic approach to morbid obesity has increased two and a half-fold worldwide between 2003 and 2011 [5].Although many studies have demonstrated the short-and long-term efficacy of bariatric surgery for weight loss, there are limited data regarding any long-term side effects of these procedures. Recently, there has been an increased focus on the impact of bariatric surgery on bone metabolism, with the concern that bariatric surgery may increase skeletal fragility and fracture risk by accelerating bone loss.The majority of research performed in this area has been cross-sectional and provides little evidence as to the possible mechanisms for any observed abnormal...

Effects of obesity treatments on bone mineral density, bone turnover and fracture risk in adults with overweight or obesity

“…BMD is dependent on the net balance between bone formation and resorption, however, these changes cannot be detected by DXA scans until substantial bone turnover has taken place, which can take between 6 and 12 months depending on the stimulus [10,31]. Moreover, the precision of DXA scans has been shown to decline with increasing BMI [32], as well as when measuring BMD in people who are not weight-stable (i.e.…”

“…undergoing dynamic changes in body weight) [33]. These imprecisions are due to several reasons, notably difficulties in positioning patients/participants on the scanning bed, fractures in the vertebrae, which heighten apparent spinal BMD, and artifact errors caused by changing amounts of fat tissue surrounding bones [10,12,34]. Indeed, the presence of fat around bone can result in unpredictable errors in DXA bone measurements of up to 20%, as determined by experiments where phantom bone models or lean participants were wrapped with plastic bags containing semi-solid fat [33,35].…”

“…after weight loss) [33]. Despite these limitations, DXA is still used and recommended as the principle method for assessing bone mass, even in obesity [10,31,36]. Nevertheless, it has been suggested that when conducting and interpreting data from studies that present potential DXA measurement errors (as in the case of obesity treatments), it is crucial that the DXA scanner be calibrated correctly [36], and that other modes of assessing bone mass are used for confirmation.…”

“…Indeed, while low BMI (< 18.5 kg/m 2 ) is clearly associated with low BMD and a higher risk of fracture, new research shows that the relationship between higher BMIs and fracture risk is nonlinear [8]. Now, obesity is no longer considered to be protective against osteoporosis and fracture [9][10][11][12]. Obesity per se is increasingly recognized as a state of heightened fracture risk in both men and women [7,8].…”

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

“…30 kg/m 2 and increased risk of ankle and upper leg fractures (with reduced risk of wrist fractures), (10) and a similar correlation was also found in men, albeit only after correction for the increased BMD generally associated with obesity, (11) and not without controversy. (12) Whether or not obesity per se has an effect on fracture risk, emerging evidence suggests that obesity treatment, namely bariatric surgery-which induces weight losses of up to 75% of excess body weight that are maintained for up to 10 to 14 years postsurgery (13) -results in bone loss. (14,15) However dietinduced weight loss, not bariatric surgery, with or without concomitant physical activity, is seen as the first treatment option for overweight and obesity.…”