Gastrointestinal hormones and appetite ratings after weight loss induced by diet or bariatric surgery

Changes in insulin sensitivity and gut peptides 8 and 52 weeks after bariatric surgery or low-calorie diet

The endocrine consequences of weight loss by bariatric surgery (BS) and caloric restriction are not fully understood but contribute to variable improvements in insulin sensitivity and cardiometabolic health. This study compared changes in insulin sensitivity and plasma concentrations of gut peptides 8 weeks and 1 year after BS and a low-calorie diet (LCD). Nineteen female patients with obesity self-selected BS (gastric bypass [n = 5] or sleeve gastrectomy [n = 7]) or LCD (n = 7) in this parallel-arm, prospective observational study. We assessed insulin sensitivity via a two-step hyperinsulinemic-euglycemic clamp (20 and 80 mU/min/m2 insulin). Plasma glucose, insulin, and gut peptides were measured around a mixed meal tolerance test (400 kcal). Visual analogue scales (VAS) were used to rate subjective appetite sensations. All assessments were conducted at baseline and after 8 weeks and 1 year of intervention. Whole-body insulin sensitivity was unchanged 8 weeks after the intervention. One year after surgery, insulin sensitivity at both 20 and 80 mU/m2/min insulin infusion doses increased with BS weight loss (-33.8% ± 1.4% body weight) but was unchanged in LCD with small weight loss (-3.7% ± 2.0% body weight). Postprandial total PYY increased more following BS while total and acylated ghrelin decreased more following BS compared to LCD. Hunger decreased and fullness increased with BS compared to LCD (p = .037; p = .010, respectively). Insulin sensitivity was improved only 1 year after BS, despite significant weight loss after 8 weeks. Changes in gut peptides after BS paralleled reduced hunger and increased fullness. Most improvements in cardiometabolic health were related to weight loss.

Plasma concentration of gastrointestinal hormones and subjective appetite ratings after diet or bariatric surgery: 1-year results from the DISGAP study

OBJECTIVE

Long-term weight loss outcomes are contrasting between bariatric surgery and dietary restriction alone. This is the first study to investigate changes in gastrointestinal (GI) hormones involved in appetite regulation, and subjective appetite feelings, at 1-year follow-up, after initial weight loss induced by a very-low energy (VLED) alone (controls), or with bariatric surgery.

METHODS

Patients scheduled for Sleeve Gastrectomy (SG) (n = 19) or Roux-en-Y gastric Bypass (RYGB) (n = 19), and controls (n = 16) were recruited. All groups underwent 10 weeks of a VLED (initial phase), followed by a 9-month maintenance phase. Body weight/composition, plasma concentrations of ghrelin, glucagon-like peptide 1 (GLP-1), peptide YY (PYY), cholecystokinin (CCK), and appetite ratings were measured before and after a meal, at baseline, week 11(W11), and 1Y follow-up.

RESULTS

Participants who completed all three follow ups were included in the analysis. Initial changes in body weight/composition were comparable across groups. SG (n = 11) and RYGB (n = 12) continued to lose weight from W11 to 1Y, whereas controls (n = 12) had regained weight. Postprandial GLP-1 increased over time post bariatric surgery and remained unchanged and lower in controls. Postprandial PYY increased in all groups, but greatest post-RYGB. Basal ghrelin decreased over time post-SG, while a small or marked increase was seen after RYGB and diet, respectively, with the control group exhibiting the greatest basal and postprandial concentrations at 1Y. A reduction in basal and postprandial CCK was seen in controls at 1Y, while no changes were observed post-bariatric surgery. Overall, small changes in subjective appetite ratings were seen over time.

CONCLUSION

Weight change at 1Y follow up after SG and RYGB is followed by a GI hormone profile favoring a lower drive to eat and increased satiety. The opposite is seen 1Y after WL induced by dietary restriction alone.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov NCT04051190.

Incretin impact on gastric function in obesity: physiology, and pharmacological, surgical and endoscopic treatments

The aims of this review are to appraise the role of the stomach in satiation, the effects of incretin and other hormone agonists on weight loss and the role of altered gastric functions in their effects on obesity or glycaemic control. In addition to the gut in its role in enzymatic digestion and hormonal responses to nutrient ingestion, gastric motor functions include accommodation, trituration and emptying [gastric emptying (GE)] of food and elicitation of postprandial satiation and satiety. The postprandially released hormones most extensively studied and utilized therapeutically are glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). Their mechanisms of action include stimulation of pancreatic β cells to produce insulin. However, GLP-1 reduces glucagon and slows GE, whereas GIP increases glucagon and does not alter GE. Molecular modifications of GLP-1 (which has a T1/2 of 3 min) led to the development of long-acting subcutaneous or oral pharmacological agents that have been approved for the treatment of obesity, and their effects on gastric function are documented. Other medications in development target other molecular mechanisms, including glucagon and amylin. Small-molecule GLP-1 receptor agonists are promising for the treatment of obesity and may also slow GE. Bariatric surgery and endoscopy increase satiation by restricting gastric size; in addition Roux-en-Y gastric bypass and to a lesser extent sleeve gastrectomy (but not endoscopic gastroplasty) increase postprandial circulating incretins, reducing appetite. In conclusion the stomach's function is integral to the impact of the most effective pharmacological and procedural reversal of obesity related to the incretin revolution.

Is severe carbohydrate restriction necessary for appetite suppression? The ASKED randomized controlled trial

OBJECTIVE

This trial aimed to compare three low-energy diets (LEDs) with different amounts of carbohydrates (CHO) on ketosis and changes in hunger feelings in adults with obesity.

METHODS

A total of 101 adults (51 female) with obesity (BMI, mean [SEM], 34.7 [0.4] kg/m2) were randomized to follow three isocaloric LEDs (1000 kcal/day) for 8 weeks, containing either low, medium, or high CHO (70, 100, and 130 g/day, respectively), and 4 weeks of refeeding and weight stabilization. Body weight (BW) and composition, hunger and other appetite ratings, concentrations of β-hydroxybutyrate (βHB), and appetite-related hormones were measured at baseline and at the end of weeks 8 and 12.

RESULTS

At week 8, weight loss and βHB concentrations were significantly different among groups: Low CHO group versus Medium CHO group (BW: 2.32 [0.95] kg, 95% CI: 0.44 to 4.21, p = 0.016; βHB: -0.40 [0.09] mM, 95% CI: -0.67 to -0.09, p < 0.001); Low CHO group versus High CHO group (BW: 2.29 [0.96] kg, 95% CI: 0.39 to 4.19, p = 0.016; βHB: -0.644 [0.10] mM, 95% CI: -0.84 to -0.44, p < 0.001); and Medium CHO group versus High CHO group (BW: -0.03 [0.94] kg, 95% CI: -1.89 to 1.84, p = 0.977; βHB: -0.15 [0.08] mM, 95% CI: -0.30 to 0.002, p = 0.054). No significant differences in hunger were found among groups: Low CHO group versus Medium CHO group (-10.87 [5.92] mm, 95% CI: -0.82 to 22.57, p = 0.068); Low CHO group versus Medium CHO group (7.74 [7.36] mm, 95% CI: -6.77 to 22.26, p = 0.294); and Medium CHO group versus High CHO group (-3.13 [7.48] mm, 95% CI: -17.89 to 11.63, p = 0.676).

CONCLUSIONS

Although the findings of this trial are not definitive, changes in hunger ratings with weight loss did not differ among groups. Additional studies with CHO intake of up to 130 g in 1000-kcal/day LEDs are warranted to replicate these findings.

A Systematic Review and Meta-Analysis of the Effect of Caloric Restriction on Skeletal Muscle Mass in Individuals with, and without, Type 2 Diabetes

BACKGROUND

Severe caloric restriction interventions (such as very-low-calorie diets) are effective for inducing significant weight loss and remission of type 2 diabetes (T2DM). However, suggestions of associated significant muscle mass (MM) loss create apprehension regarding their widespread use. We conducted a systematic review and meta-analysis to provide a quantitative assessment of their effect on measures of MM in individuals with, or without, T2DM.

METHODS

EMBASE, Medline, Pubmed, CINAHL, CENTRAL and Google Scholar were systematically searched for studies involving caloric restriction interventions up to 900 kilocalories per day reporting any measure of MM, in addition to fat mass (FM) or body weight (BW).

RESULTS

Forty-nine studies were eligible for inclusion, involving 4785 participants. Individuals with T2DM experienced significant reductions in MM (WMD -2.88 kg, 95% CI: -3.54, -2.22; p < 0.0001), although this was significantly less than the reduction in FM (WMD -7.62 kg, 95% CI: -10.87, -4.37; p < 0.0001). A similar pattern was observed across studies involving individuals without T2DM. MM constituted approximately 25.5% of overall weight loss in individuals with T2DM, and 27.5% in individuals without T2DM. Subgroup analysis paradoxically revealed greater BW and FM reductions with less restrictive interventions.

CONCLUSIONS

Our review suggests that caloric restriction interventions up to 900 kilocalories per day are associated with a significant reduction in MM, albeit in the context of a significantly greater reduction in FM. Furthermore, MM constituted approximately a quarter of the total weight loss. Finally, our data support the use of less restrictive interventions, which appear to be more beneficial for BW and FM loss.

Molecular Mechanisms Affecting Statin Pharmacokinetics after Bariatric Surgery

According to recent data, one in eight people in the world struggle with obesity. Obesity management is increasingly dependent on bariatric surgical interventions, as the combination of lifestyle modifications and pharmacotherapy could have a modest long-term effect. Surgery is recommended only for individuals whose body mass index (BMI) ≥ 40 kg/m2 and ≥ 35 kg/m2 in the presence of weight-related comorbidities. The most commonly performed procedures are sleeve gastrectomy and roux-en-Y gastric bypass. Pharmacokinetic and pharmacodynamic alterations occur as a result of the anatomical and physiological changes caused by surgery, which further differ depending on physicochemical drug factors and factors related to the dosage form. The following modifications are distinguished based on the type of bariatric surgery performed. Most bariatric patients have accompanying comorbidities, including dyslipidemia treated with hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors or statins. Significant improvements in the lipid profile are observed early in the postoperative period. The data reported in this review on statin pharmacokinetic alterations have demonstrated substantial inter- and intravariability, making it difficult to adopt clear guidelines. Based on the current literature review, reducing the statin dose to the lowest effective with continuous monitoring is considered an optimal approach in clinical practice.

The Potential Mechanism of Remission in Type 2 Diabetes Mellitus After Vertical Sleeve Gastrectomy

In recent years, there has been a gradual increase in the prevalence of obesity and type 2 diabetes mellitus (T2DM), with bariatric surgery remaining the most effective treatment strategy for these conditions. Vertical sleeve gastrectomy (VSG) has emerged as the most popular surgical procedure for bariatric/metabolic surgeries, effectively promoting weight loss and improving or curing T2DM. The alterations in the gastrointestinal tract following VSG may improve insulin secretion and resistance by increasing incretin secretion (especially GLP-1), modifying the gut microbiota composition, and through mechanisms dependent on weight loss. This review focuses on the potential mechanisms through which the enhanced action of incretin and metabolic changes in the digestive system after VSG may contribute to the remission of T2DM.

Lower levels of plasma syndecan-4 are associated with loss of body weight and fat-free mass after bariatric surgery

OBJECTIVE

Bariatric surgery induces a significant loss of both fat mass (FM) and fat-free mass (FFM). The proteoglycan receptor syndecan-4 (SDC4) plays a crucial role in adipose tissue and skeletal muscle functions. Thus, this study was performed (i) to assess plasma SDC4 levels after both Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB) surgeries, and (ii) to explore potential associations with changes in body composition variables.

RESULTS

Twenty-six patients (17 females) with severe obesity underwent SG (n = 13) or RYGB (n = 13) and were followed up to 1 year (1Y). Body weight, FM, FFM, and SCD4 were measured at baseline (BL), and at week 11 (W11) and 1Y after surgery. Independently of procedure, there was a significant body weight loss at W11, with an average FM and FFM reduction of 13.7 ± 0.6 kg and 5.3 ± 0.5 kg, respectively. Participants continued to lose weight afterwards, with a total weigth loss of 38.2 ± 1.5 kg at 1Y. No associations were found at BL between SDC4 levels and any anthropometric variable; however, SDC4 levels were lower than BL at both W11 and 1Y, independently of type of surgery. Additionally, changes in SDC4 between BL and 1Y were positively correlated with weight and FFM loss during the same period.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04051190 on 09/08/2019.

Adaptive thermogenesis, at the level of resting energy expenditure, after diet alone or diet plus bariatric surgery

OBJECTIVE

The objective of this study was to compare the magnitude of adaptive thermogenesis (AT), at the level of resting energy expenditure (REE), after a very low-energy diet alone or combined with Roux-en-Y gastric bypass or sleeve gastrectomy, as well as to investigate the association between AT and changes in appetite.

METHODS

A total of 44 participants with severe obesity underwent 10 weeks of a very low-energy diet alone or combined with Roux-en-Y gastric bypass or sleeve gastrectomy. Body weight and composition, REE, subjective appetite feelings, and plasma concentrations of gastrointestinal hormones were measured at baseline and week 11. AT, at the level of REE, was defined as a significantly lower measured versus predicted (using a regression model with baseline data) REE.

RESULTS

Participants lost 18.4 ± 3.9 kg of body weight and experienced AT, at the level of REE (-121 ± 188 kcal/day; p < 0.001), with no differences among groups. The larger the AT, at the level of REE, the greater the reduction in fasting ghrelin concentrations and the smaller the reduction in feelings of hunger and desire to eat in the postprandial state.

CONCLUSIONS

Weight-loss modality does not seem to modulate the magnitude of AT, at the level of REE. The greater the AT, at the level of REE, the greater the drive to eat following weight loss.

Control of Eating Attributes and Weight Loss Outcomes over One Year After Sleeve Gastrectomy

PURPOSE

Sleeve gastrectomy (SG) is a commonly performed metabolic-bariatric surgery, but its effectiveness is variable and difficult to predict. Our study aimed to compare control of eating (CoE) attributes pre- and post-SG depending on the achievement of optimal weight loss target at 1 year post-SG.

MATERIALS AND METHODS

A prospective longitudinal cohort study using the CoE Questionnaire, pre-SG, and postoperatively at 3, 6, and 12 months was conducted. Total weight loss (TWL) ≥ 25% at 12 months post-SG was set as an optimal weight loss target.

RESULTS

Forty-one patients (80.5% females, mean age 41.7 ± 10.6) were included. Sex, age, baseline weight, BMI, and smoking status were all comparable. At 3 months post-SG, "difficulty to control eating" score became significantly different between ≥ 25%TWL and < 25%TWL groups (7 [0-50] vs. 17 [5-63], p = 0.042). At 6 months, it was followed by "feeling of fullness," "frequency of food cravings," and "difficulty to resist cravings" demonstrating significant differences between ≥ 25%TWL and < 25%TWL groups. At 12 months, significant differences between groups were observed in "feeling hungry," "difficulty to resist cravings," "eating in response to cravings," and difficulty to control eating scores.

CONCLUSION

Individuals with obesity who achieved a target of ≥ 25%TWL at 1 year post-SG have an early improvement in overall eating control at 3 months that steadily persists at 6 and 12 months. Improvements in other aspects tend to follow later, at 6 and 12 months. These findings may assist in identifying individuals with inadequate response to help attain optimal weight loss targets and developing a prognostic model to identify predictors of successful weight loss.

The role of gastric function in control of food intake (and body weight) in relation to obesity, as well as pharmacological and surgical interventions

PURPOSE

The objectives of this review are to summarize the role of gastric motor functions in the development of satiation (defined broadly as postprandial fullness) and satiety (reduced appetite or postponing desire to eat after a meal) and their impact on weight change. The specific topics are the methods of measurement of gastric emptying and accommodation and their impact on food intake, satiation, and satiety. A second focus contrasts bariatric surgery to endoscopic gastroplasty that alter gastric emptying and incretin responses in markedly divergent manners.

BACKGROUND

The hormone, GLP-1, retards gastric emptying and increases gastric accommodation through vagally-mediated effects. Indeed, these effects provide the basis for the association of altered gastric emptying in the appetite and weight loss responses to pharmacological interventions particularly by those acting on receptors of incretin agonists such as liraglutide and the dual agonists, tirzepatide and cotadutide, all of which retard gastric emptying. In fact, retardation of gastric emptying and gastrointestinal adverse effects have been shown to contribute in part to the weight loss in response to this class of pharmacological agents.

SUMMARY

The motor functions of the stomach are relevant to postprandial fullness and to interventions aimed at weight loss in people with obesity.

Suboptimal Weight Loss 13 Years After Roux-en-Y Gastric Bypass Is Associated with Blunted Appetite Response

PURPOSE

Bariatric surgery remains the most efficient treatment to achieve a sustained weight loss. However, a large proportion of patients experience suboptimal weight loss (SWL). The exact mechanisms involved remain to be fully elucidated, but the homeostatic appetite control system seems to be involved. The aim of this study was, therefore, to compare the plasma concentration of gastrointestinal hormones, and appetite ratings, between those experiencing SWL and optimal weight loss (OWL) after Roux-en-Y gastric bypass (RYGB).

MATERIALS AND METHODS

Fifty participants from the Bariatric Surgery Observation Study (BAROBS) experiencing either SWL or OWL (< or ≥ 50% of excess weight loss (EWL), respectively) > 13 years post-RYGB were compared to 25 non-surgical controls. Plasma concentrations of acylated ghrelin (AG), total glucagon-like peptide-1 (GLP-1), total peptide YY (PYY), cholecystokinin (CCK), and subjective ratings of hunger, fullness, desire to eat (DTE), and prospective food consumption (PFC) were assessed in the fasting and postprandial (area under the curve (AUC)) states.

RESULTS

Those experiencing OWL presented with higher basal AG and GLP-1 iAUC, and lower AG iAUC compared with SWL and controls. Additionally, both bariatric groups presented with higher PYY and CCK iAUC compared to controls. PFC tAUC was also lower in OWL compared to the SWL group. Total weight loss was positively correlated with GLP-1 tAUC and negatively correlated with fasting and tAUC DTE and PFC tAUC.

CONCLUSIONS

SWL > 13 years post-RYGB is associated with lower basal ghrelin, as well as a weaker satiety response to a meal. Future studies should investigate the causality of these associations.

Our biology working against us in obesity: A narrative review on implications for management of osteoarthritis

Obesity is the major modifiable risk factor for osteoarthritis (OA). A major focus of management in OA is weight loss. Although we live in an obesogenic environment, obesity has a predominantly genetic and epigenetic basis. This explains a person's weight set point which is defended by biological mechanisms making weight loss difficult to achieve and maintain long term, regardless of the methods used. Significant weight regain occurs after weight loss, with weight tending to return to pre-treatment levels after cessation of interventions including the glucagon-like peptide-1 (GLP-1) agonists. An area that has received little attention is the slow, insidious weight creep of 0.5-1 kg/year over adulthood that sees individuals relentlessly increase weight. There is evidence that low intensity, personalised lifestyle interventions can prevent this weight creep, providing patients with achievable goals. In this narrative review, we examine the evidence for weight loss in OA, the biological mechanisms that make weight loss difficult to achieve and maintain and the potential negative impacts on patients. We review the evidence for preventing weight gain, the improvement in patient outcomes and the potential for significant healthcare savings through reduced knee replacements. We propose a combined approach of weight loss when indicated, together with targeting weight creep across adult years and the potential role of metformin. Implementing these combined approaches is likely to be more effective in improving patient related outcomes, reducing joint damage and healthcare costs, than our current focus on achieving weight loss in OA.

Association between ß-Hydroxybutyrate Plasma Concentrations after Hypocaloric Ketogenic Diets and Changes in Body Composition

BACKGROUND

Early studies show that ketogenic diets (KDs) lead to preferential loss of fat mass (FM), whereas preserving fat-free mass (FFM). Additionally, animal data support the anticatabolic effects of DL-3-hydroxybutyrate. From our knowledge, a potential association between ß-hydroxybutyrate (ßHB) plasma concentrations and changes in body composition has never been explored.

OBJECTIVES

The main aim of this analysis was to determine if ßHB plasma concentrations, following hypocaloric KDs, were associated with FM and FFM changes in men and women with obesity.

METHODS

Data from 199 individuals (BMI = 36.6 ± 4.3 kg/m2; age = 43.6 ± 9.8 y; 82 men) were collated from 3 weight loss studies employing common measures of body composition (air displacement plethysmography) and ßHB plasma concentration (ELISA). The association between ßHB and weight, FM and FFM loss (kg), and %FFM loss (%FFML) was investigated with Spearman correlation. Multivariable linear regression was used to determine if ßHB was a significant predictor of the changes in anthropometric variables, after adjusting for confounding factors.

RESULTS

ßHB was not associated with FFML (% or kg), but a weak positive association was seen with FM loss (r = 0.182, P = 0.01, n = 199) and a trend with weight loss (r = 0.128, P = 0.072, n = 199). ßHB was a significant predictor of both weight and FM loss (kg), after adjusting for age, sex, baseline BMI, and intervention study.

CONCLUSIONS

The magnitude of ketosis is not associated with FFM preservation. However, the higher the level of ketosis, the greater the weight and FM loss. Further studies are needed to confirm these findings and to explore the mechanisms involved. This trial was registered at clinicaltrials.gov identifier as NCT01834859, NCT04051190, NCT02944253.