Early reduction of resting energy expenditure and successful weight loss after Roux-en-Y gastric bypass

Embracing the Pros and Cons of the New Weight Loss Medications (Semaglutide, Tirzepatide, Etc.)

PURPOSE OF REVIEW

The history of multiple weight loss medications has been a concerning paradox based on an increased cardiovascular risk despite significant reductions in adipose tissue and weight. A new class of weight loss medications could change this past narrative based on early preliminary results of cardiovascular risk (not events-still need to be determined) and weight reduction in non-diabetics that acutely competes with results achieved with bariatric surgery. The purpose of this review is to provide a comprehensive summary of the advantages and disadvantages of these newer medications, and how they could impact urology.

RECENT FINDINGS

Weight loss of - 15 to - 20% compared to baseline has become plausible in the short-term and preliminary guidance to reduce acute and chronic adverse events are receiving attention. However, the cost, access, conflicts of interest, supply chain, life-long adherence issues, and the long-term diverse implications on mental and physical health when exposed to this class of medications (GLP-1 agonists) are unknown. The profound caloric reductions should also result in baseline or ongoing nutritional deficiency testing, and general and specific dietary recommendations, which could theoretically mimic some bariatric surgery pre- and post-surgical protocols but has yet to be studied. Regardless, the potential impact of these medicines within a variety of medical specialties needs clinical research. Current and future lifestyle interventions, dietary patterns, and medicines in the weight loss category need to be held to a paradigm whereby cardiovascular health should improve with significant weight loss without a negative impact on mental health. In urology, the ability to impact cancer risk, ED, FSD, incontinence, infertility, nephrolithiasis, and multiple other endpoints are plausible (based on bariatric surgery data) but need preliminary clinical research. Other medicines with a similar or even larger potential impact are in clinical trials, and thus, a concise overview for clinicians and researchers was needed for objective guidance. Currently, comprehensive lifestyle changes utilized with and without these medications continue to garner positive mental, physical, and legacy effects, which suggest that they are as necessary as ever in the treatment of the numerous conditions impacted by unhealthy weight gain.

Evolution of the basal metabolic rate after Roux-en-Y gastric bypass: a systematic review and meta-analysis

Patients who undergo Roux-en-Y gastric bypass (RYGB) exhibit a reduction in total basal metabolic rate (BMR) after surgery, which seems to be intimately related to the amount of postoperative weight loss. The objective was to perform a systematic review and meta-analysis of the literature to determine and evaluate BMR changes after RYGB. The search was performed in certified databases, and the strategy was structured according to the PRISMA ScR. The quality evaluation of the articles included in this review was assessed with two different bias risk tools (ROBINS-I and NIH) according to each study design. Two meta-analyses were elaborated based on the results. 163 articles were selected (from 2016 to 2020), and 9 articles met the inclusion criteria. All of the selected studies evaluated only adult patients, mostly women. Postoperative BMR diminished in all of the included studies after surgery compared to preoperative values. The follow-up periods were 6, 12, 24 and 36 months. Eight articles were used for the meta-analysis after the quality assessment, a total of 434 participants. Compared to baseline values, mean postoperative reductions of 356.66 kcal/d after 6 months (p < 0.001) and 432.89 kcal/d (p < 0.001) after 1 year were observed. The BMR decreases during the first years after Roux-en-Y gastric bypass, especially during the first year postsurgery.

Postoperative Resting Metabolic Rate and Successful Weight Loss After Roux-en-Y Gastric Bypass

OBJECTIVE

To analyze whether changes in RMR 6 months after RYGB could be a predictor of weight loss on late follow-up.

METHODS

Prospective study of 45 individuals submitted to RYGB in a university tertiary care hospital. Body composition was evaluated by bioelectrical impedance analysis and RMR by indirect calorimetry before (T0), 6 (T1), and 36 months (T2) after surgery.

RESULTS

RMR/day was lower in T1 (1.552 ± 275 kcal/day) than in T0 (1734 ± 372 kcal/day; p < 0.001) with a return to similar values at T2 (1.795 ± 396 kcal/day; p < 0.001). In T0, there was no correlation between RMR/kg and body composition. In T1, there was a negative correlation between RMR and BW, BMI, and % FM, and a positive correlation with % FFM. The results in T2 were similar to T1. There was a significant increase in RMR/kg between T0, T1, and T2 (13.6 ± 2.2 kcal/kg, 16.9 ± 2.7 kcal/kg, and 19.9 ± 3.4 kcal/kg) in the total group and according to gender. Eighty percent of the patients who had increased RMR/kg ≥ 2 kcal at T1 achieved > 50% EWL in T2, particularly in women (odds ratio: 27.09, p < 0.037).

CONCLUSIONS

The increase in RMR/kg after RYGB is a major factor related to a satisfactory % excess weight loss on late follow-up.

Fat-Free Mass and Skeletal Muscle Mass Gain Are Associated with Diabetes Remission after Laparoscopic Sleeve Gastrectomy in Males but Not in Females

Besides massive body weight loss, laparoscopic sleeve gastrectomy (LSG) causes massive lean mass, including fat-free mass (FFM) and skeletal muscle mass (SM) that present higher metabolic rates in males. This study examines sex differences in FFM and SM changes of type 2 diabetes (T2D) remission at 12 months post-LSG. This cohort study recruited 119 patients (53.7% females) with T2D and obesity (body mass index 42.2 ± 7.0 kg/m²) who underwent LSG. Fat-mass (FM) loss was higher in males than in females (−12.8 ± 6.2% vs. −9.9 ± 5.0%, p = 0.02) after one-year post-operation. Regardless of the weight-loss difference, males had higher FFM and SM gain than did females (12.8 ± 8.0 vs. 9.9 ± 5.0% p = 0.02 and 6.5 ± 4.3% vs. 4.9 ± 6.2%, p = 0.03, respectively). Positive correlations of triglyceride reduction with FM loss (r = 0.47, p = 0.01) and SM gain (r = 0.44, p = 0.02) over 12 months post-operation were observed in males who achieved T2D remission. The T2D remission rate significantly increased 16% and 26% for each additional percentage of FFM and SM gain one year after LSG, which only happened in males. Increased FFM and SM were remarkably associated with T2D remission in males, but evidence lacks for females.

The magnitude and progress of lean body mass, fat-free mass, and skeletal muscle mass loss following bariatric surgery: A systematic review and meta-analysis

Postbariatric loss of muscle tissue could negatively affect long-term health due to its role in various bodily processes, such as metabolism and functional capacity. This meta-analysis aimed to unravel time-dependent changes in the magnitude and progress of lean body mass (LBM), fat-free mass (FFM), and skeletal muscle mass (SMM) loss following bariatric surgery. A systematic literature search was conducted in Pubmed, Embase, and Web of Science. Fifty-nine studies assessed LBM (n = 37), FFM (n = 20), or SMM (n = 3) preoperatively and ≥1 time points postsurgery. Random-effects meta-analyses were performed to determine pooled loss per outcome parameter and follow-up time point. At 12-month postsurgery, pooled LBM loss was -8.13 kg [95%CI -9.01; -7.26]. FFM loss and SMM loss were -8.23 kg [95%CI -10.74; -5.73] and -3.18 kg [95%CI -5.64; -0.71], respectively. About 55% of 12-month LBM loss occurred within 3-month postsurgery, followed by a more gradual decrease up to 12 months. Similar patterns were seen for FFM and SMM. In conclusion, >8 kg of LBM and FFM loss was observed within 1-year postsurgery. LBM, FFM, and SMM were predominantly lost within 3-month postsurgery, highlighting that interventions to mitigate such losses should be implemented perioperatively.

Body Composition, Basal Metabolic Rate and Leptin in Long-Term Weight Regain After Roux-en-Y Gastric Bypass Are Similar to Pre-surgical Obesity

PURPOSE

The purpose of this study is to evaluate the relationship between body composition, basal metabolic rate (BMR), and serum concentrations of leptin with long-term weight regain after Roux-en-Y gastric bypass (RYGB) and compare it with obesity before surgery.

MATERIALS AND METHODS

Prospective longitudinal analytical study. Three groups were formed: individuals 60 months post RYGB, with weight regain (G1) and without it (G2), and individuals with obesity who had not undergone bariatric surgery (G3). Body fat (BF), body fat mass (BFM), visceral fat (VF), fat-free mass (FFM), skeletal muscle mass (SMM), and BMR were assessed by octapolar and multi-frequency electrical bioimpedance. Fasting serum concentrations of leptin were measured.

RESULTS

Seventy-two individuals were included, 24 in each group. Higher means of BF, BFM, VF, and leptin levels were observed in G1, when compared to G2 (BF: 47.5 ± 5.6 vs. 32.0 ± 8.0, p < 0.05; FBM: 47.8 ± 11.6 vs. 23.9 ± 7.0, p < 0.05; VF: 156.8 ± 30.2 vs. 96.1 ± 23.8, p < 0.05; leptin: 45,251.2 pg/mL ± 20,071.8 vs. 11,525.7 pg/mL ± 9177.5, p < 0.000). G1 and G2 did not differ in FFM, SMM, and BMR. G1 and G3 were similar according to BF, FFM, BMR, and leptin levels. Body composition, but not leptin, was correlated with %weight regain in G1 (FBM: r = 0.666, p < 0.000; BF: r = 0.428, p = 0.037; VF: r = 0.544, p = 0.006).

CONCLUSION

Long-term weight regain after RYGB is similar to pre-surgical obesity in body composition, BMR, and leptin concentrations, indicating relapse of metabolic and hormonal impairments associated with excessive body fat.

Plasma progranulin levels in obese patients before and after Roux-en-Y gastric bariatric surgery: a longitudinal study

BACKGROUND

Bariatric surgery stands out as the most effective long-term intervention for sustainable weight loss and metabolic improvement in patients with severe obesity. Progranulin was recently identified as an adipokine related to obesity and inflammation, revealing a metabolic function and proinflammatory properties.

OBJECTIVE

To evaluate plasma progranulin levels before and after 6 months of bariatric surgery in Roux-en-Y gastric bypass (RYGB).

SETTING

Tertiary referral hospital, southern Brazil.

METHODS

This was a prospective longitudinal study, including 23 obese patients who underwent RYGB. Demographic and clinical characteristics, body composition, and resting energy expenditure were evaluated. Plasma progranulin was determined with enzyme-linked immunosorbent assays in a peripheral blood sample collected before and 6 months after the surgical procedure.

RESULTS

The participants were mostly women (78.3%), with a mean age of 42.3 ± 10.8 years and baseline body mass index of 48.8 ± 10.4 kg/m². Regarding the anthropometric parameters, there were differences in the pre- and post-RYGB values, with reduction of weight, body mass index, body fat percentage, and cervical and abdominal circumferences. All laboratory parameters improved, such as lipid profile and fasting glycemia, and resting energy expenditure values decreased significantly. Plasma progranulin levels decreased from 47.6 ± 13.5 ng/mL before RYGB to 40.4 ± 9.9 ng/mL after 6 months of surgery (P = .005). The reduction of progranulin did not correlate with body composition or laboratory data.

CONCLUSIONS

Plasma progranulin levels significantly reduced 6 months after RYGB, but it could not be explained by changes in anthropometry, body composition, or glycemic or lipid profile.

Metabolic benefits of gastric bypass surgery in the mouse: The role of fecal losses

Objective

Roux-en-Y gastric surgery (RYGB) promotes a rapid and sustained weight loss and amelioration of glucose control in obese patients. A high number of molecular hypotheses were previously tested using duodenal-jejunal bypass (DJB) performed in various genetic models of mice with knockouts for various hormones or receptors. The data were globally negative or inconsistent. Therefore, the mechanisms remained elusive. Intestinal gluconeogenesis is a gut function that has been suggested to contribute to the metabolic benefits of RYGB in obese patients.

Methods

We studied the effects of DJB on body weight and glucose control in obese mice fed a high fat-high sucrose diet. Wild type mice and mice with a genetic suppression of intestinal gluconeogenesis were studied in parallel using glucose- and insulin-tolerance tests. Fecal losses, including excretion of lipids, were studied from the feces recovered in metabolic cages.

Results

DJB induced a dramatic decrease in body weight and improvement in glucose control (glucose- and insulin-tolerance) in obese wild type mice fed a high calorie diet, for 25 days after the surgery. The DJB-induced decrease in food intake was transient and resumed to normal in 7–8 days, suggesting that decreased food intake could not account for the benefits. Total fecal losses were about 5 times and lipid losses 7 times higher in DJB-mice than in control (sham-operated and pair-fed) mice, and could account for the weight loss of mice. The results were comparable in mice with suppression of intestinal gluconeogenesis. There was no effect of DJB on food intake, body weight or fecal loss in lean mice fed a normal chow diet.

Conclusions

DJB in obese mice fed a high calorie diet promotes dramatic fecal loss, which could account for the dramatic weight loss and metabolic benefits observed. This could dominate the effects of the mouse genotype/phenotype. Thus, fecal energy loss should be considered as an essential process contributing to the metabolic benefits of DJB in obese mice.

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Duodenal-jejunal bypass (DJB) promotes weight loss in mice fed a high calorie diet.

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DJB induces dramatic fecal energy losses in mice fed a high calorie diet.

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DJB has no effect in mice fed a control (starch-based) diet.

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There is no fecal losses in DJB-mice fed a control diet.

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Fecal energy loss is a cause of body weight loss in DJB-mice fed high calorie diet.

Resting Energy Expenditure and Metabolic Adaptation in Adolescents at 12 Months After Bariatric Surgery

BACKGROUND

Evidence suggests that metabolic adaptation occurs after bariatric surgery such that resting energy expenditure (REE) declines more than accounted for by body weight or body composition changes in adults. Little is known about REE and metabolic adaptation among adolescents after bariatric surgery.

OBJECTIVE

To examine changes in REE and metabolic adaptation among adolescents at 12 months (12M) after bariatric surgery.

SETTING

Pediatric hospital, Canada.

METHODS

Adolescents undergoing Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) were followed. Bioelectrical impedance analysis and indirect calorimetry were completed to measure body composition and REE, respectively. Predicted REE was calculated using the Mifflin equation before and after bariatric surgery and a predictive equation using preoperative data.

RESULTS

Among 20 patients (15 girls), the mean age and body mass index at surgery were 17.2 ± 0.8 years and 48.7 ± 7.4 kg/m2, respectively. REE had decreased by 548.3 kcal/d at 12M postoperatively (P < 0.001). Metabolic adaptation, determined by two procedures, was negative and significantly different from baseline (P < 0.05). When stratified by surgery type, REE change at 12M was not significantly different (RYGB, -494.0 ± 260.9 kcal/d, n = 11; SG, -614.6 ± 344.4 kcal/d, n = 9; P = 0.384). Among 13 patients with REE data at 6 and 12M, no statistically significant difference was found (P = 0.368).

CONCLUSIONS

Predicted and measured REE was 19% and 25% lower at 12M, respectively, irrespective of bariatric surgery type. Metabolic adaptation might predispose adolescents to weight regain after bariatric surgery and warrants careful nutritional management and counseling.

Changes in Energy Expenditure of Patients with Obesity Following Bariatric Surgery: a Systematic Review of Prospective Studies and Meta-analysis

We herein summarize the available literature on the effects of bariatric surgery (BS) on energy expenditure in individuals with obesity. We conducted a systematic literature review, and 35 prospective studies met our inclusion criteria. The findings indicate that BS contributes to increased diet-induced thermogenesis (DIT) and decreased total energy expenditure (TEE) and resting energy expenditure (REE) in patients with obesity. The meta-analysis demonstrated a significant decrease in TEE and REE within 6 months following BS. With the sustained decrease in REE, there was no further decrease in TEE between the 6- and 12-month follow-up. Increased DIT might explain the variance between the patterns of REE and TEE change. The postoperative decrease in REE/FFM and increase in REE/BW were observed. The changes in substrate utilization might be consistent with the change in the respiration quotient postoperatively.