Changes in Lean Tissue Mass, Fat Mass, Biological Parameters and Resting Energy Expenditure over 24 Months Following Sleeve Gastrectomy

Cross-Calibration of Areal Bone Mineral Densities and Body Composition between DMS Stratos and Hologic Horizon A Dual-Energy X-ray Absorptiometers: The Effect of Body Mass Index

PURPOSE

The aim of this study was to investigate the correlations between areal bone mineral density (aBMD) and body composition measured by two dual-energy X-ray absorptiometers (DXA), the DMS Stratos® (STR) and the Hologic Horizon A® (HRZ), and then generate cross-calibration equations between the two scanners.

METHODS

Repeat scans were obtained from 251 adults (85 % female), 36 ± 14 years old with mean body mass index (BMI) of 28.7 ± 11.1 kg/m2, using HRZ (fan-beam technology) and STR (pencil-beam technology). aBMD was measured at whole body [WB], femoral neck [FN], total hip [TH], lumbar spine [LS] and radius, while fat mass [FM] and lean tissue mass [LTM] were determined at whole body and at android and gynoid subregions.

RESULTS

Compared to HRZ, STR underestimated both aBMD at WB and radius and LTM at WB and android and gynoid regions. Conversely, STR overestimated aBMD at FN, TH, LS and FM at WB android and gynoid regions. Except for WB bone mineral content (r = 0.87) and WB aBMD (r = 0.84), there were strong correlations of aBMD and body composition between the two DXAs (r > 0.91; p < 0.0001). Several of the parameters that required the determination of specific cross-calibration equations because of the significant bias between the two DXAs were found to be influenced by BMI.

CONCLUSIONS

Although the data from the STR and the HRZ were highly correlated for aBMD and body composition parameters, a systematic measurement bias between two DXAs was observed. The development of cross-calibration equations fully corrected these differences and they may thus be useful for multicenter studies when scans are performed with STR and HRZ.

Association Between Indole-3-Pyruvic Acid and Change in Fat-Free Mass Relative to Weight Loss in Patients Undergoing Sleeve Gastrectomy

Sleeve gastrectomy typically leads to weight loss, including a reduction in fat-free mass (FFM). Studies have shown significant FFM loss within 1 year after the procedure but with individual variations. This study aimed to assess whether preoperative amino acid metabolite levels can predict FFM changes following sleeve gastrectomy. This study involved 42 patients. Body weight, fat mass (FM), and FFM were measured preoperatively and 3, 6, and 12 months postoperatively. All participants experienced weight loss, FM reduction, and FFM decrease for up to 3 months after surgery. However, the following distinct groups emerged from 3 to 6 months postoperatively: one showed FFM gain relative to weight loss, whereas the other exhibited continued FFM reduction relative to weight loss. This trend persisted for up to 12 months postoperatively and became more pronounced. The group with FFM gain had lower preoperative BMI and higher levels of indole-3-pyruvic acid (IPyA). Logistic regression and ROC curve analyses confirmed IPyA's ability to predict FFM gain between 3 and 6 months after sleeve gastrectomy, with a useful cutoff value of 20.205. Preoperative IPyA levels were associated with FFM gain relative to weight loss in the 3 to 6 months following sleeve gastrectomy. These findings suggest that IPyA may be a potential predictor for FFM changes during this period.

A multifaceted and inclusive methodology for the detection of sarcopenia in patients undergoing bariatric surgery: an in-depth analysis of current evidence

Bariatric surgery is widely recognized as the most effective intervention for obesity and offers benefits beyond weight loss. However, not all patients achieve satisfactory weight loss, balanced changes in body composition, and resolution of comorbidities. Therefore, thorough pre- and postoperative evaluations are important to predict success and minimize adverse effects. More comprehensive assessments require broadening the focus beyond body weight and fat measurements to consider quantitative and qualitative evaluations of muscles. Introducing the concept of sarcopenia is useful for assessing the degradative and pathological changes in muscles associated with cardiometabolic function, physical performance, and other obesity-related comorbidities in patients undergoing bariatric surgery. However, there is currently no consensus or definition regarding the research and clinical use of sarcopenia in patients undergoing bariatric surgery. Therefore, this review aimed to define the concept of sarcopenia applicable to patients undergoing bariatric surgery, based on the consensus reached for sarcopenia in the general population. We also discuss the methods and significance of measuring muscle mass, quality, and strength, which are key variables requiring a comprehensive assessment.