Association between gastrointestinal phenotypes and weight gain in younger adults: a prospective 4-year cohort study

Reduced Liver Mitochondrial Energy Metabolism Impairs Food Intake Regulation Following Gastric Preloads and Fasting

Objective

The capacity of the liver to serve as a peripheral sensor in the regulation of food intake has been debated for over half a century. The anatomical position and physiological roles of the liver suggest it is a prime candidate to serve as an interoceptive sensor of peripheral tissue and systemic energy state. Importantly, maintenance of liver ATP levels and within-meal food intake inhibition is impaired in human subjects with obesity and obese pre-clinical models. Previously, we have shown decreased hepatic mitochondrial energy metabolism (i.e., oxidative metabolism & ADP-dependent respiration) in male liver-specific, heterozygous PGC1a mice results in increased short-term diet-induced weight gain with increased within meal food intake. Herein, we tested the hypothesis that decreased liver mitochondrial energy metabolism impairs meal termination following nutrient oral pre-loads.

Methods

Liver mitochondrial respiratory response to changes in ΔG ATP and adenine nucleotide concentration following fasting were examined in male liver-specific, heterozygous PGC1a mice. Further, food intake and feeding behavior during basal conditions, following nutrient oral pre-loads, and following fasting were investigated.

Results

We observed male liver-specific, heterozygous PGC1a mice have reduced mitochondrial response to changes in ΔG ATP and tissue ATP following fasting. These impairments in liver energy state are associated with larger and longer meals during chow feeding, impaired dose-dependent food intake inhibition in response to mixed and individual nutrient oral pre-loads, and greater acute fasting-induced food intake.

Conclusion

These data support previous work proposing liver-mediated food intake regulation through modulation of peripheral satiation signals.

Precision medicine for obesity: current evidence and insights for personalization of obesity pharmacotherapy

Obesity is a chronic and complex disease associated with increased morbidity, mortality, and financial burden. It is expected that by 2030 one of two people in the United States will have obesity. The backbone for obesity management continues to be lifestyle interventions, consisting of calorie deficit diets and increased physical activity levels, however, these interventions are often insufficient to achieve sufficient and maintained weight loss. As a result, multiple patients require additional interventions such as antiobesity medications or bariatric interventions in order to achieve clinically significant weight loss and improvement or resolution of obesity-associated comorbidities. Despite the recent advances in the field of obesity pharmacotherapy that have resulted in never-before-seen weight loss outcomes, comorbidity improvement, and even reduction in cardiovascular mortality, there is still a significant interindividual variability in terms of response to antiobesity medications, with a subset of patients not achieving a clinically significant weight loss. Currently, the trial-and-error paradigm for the selection of antiobesity medications results in increased costs and risks for developing side effects, while also reduces engagement in weight management programs for patients with obesity. The implementation of a precision medicine framework to the selection of antiobesity medications might help reduce heterogeneity and optimize weight loss outcomes by identifying unique subsets of patients, or phenotypes, that have a better response to a specific intervention. The detailed study of energy balance regulation holds promise, as actionable behavioral and physiologic traits could help guide antiobesity medication selection based on previous mechanistic studies. Moreover, the rapid advances in genotyping, multi-omics, and big data analysis might hold the key to discover additional signatures or phenotypes that might respond better to a certain intervention and might permit the widespread adoption of a precision medicine approach for obesity management.

Cumulative effect of obesity phenotypes on body weight and body mass index

BACKGROUND

Obesity originates from an imbalance between energy intake and expenditure. Changes in energy intake components (satiation, postprandial satiety, emotional eating) and energy expenditure have been linked to obesity and are referred to as obesity phenotypes. We aim to study if these obesity phenotypes have a cumulative effect on body weight and body mass index (BMI).

SUBJECT/METHODS

This is a cross-sectional study of adult patients with obesity (BMI > 30 kg/m2) who completed the validated tests to measure the obesity phenotypes. A total of 464 were included in this study.

INTERVENTIONS/METHODS

We defined higher calories to fullness during an ad libitum meal as abnormal satiation, accelerated time to half gastric emptying with scintigraphy as abnormal postprandial satiety, higher anxiety score on the Hospital Anxiety and Depression Scale as hedonic eating behavior, and decreased percentage of measured resting energy expenditure as abnormal energy expenditure. The primary analysis was done on the number of phenotypes ( ≤ 1 and ≥ 2) with body weight and BMI using an independent t-test.

RESULTS

Our cohort included 464 patients (mean [SD] age 42.0 [10.9] years, 79% females, weight 111.2 [22.9] kg, BMI 38.9 [7.0] kg/m2). There were 294 patients who had ≤ 1 phenotype, and 170 patients with ≥ 2 phenotypes with no baseline demographical differences (i.e., age and sex). Having ≥ 2 phenotypes was associated with higher body weight (115 [25] kg vs. 109 [21] kg; p = 0.004), BMI (40 [8] kg/m2 vs. 38 [7] kg/m2; p = 0.02) and waist (118 [15] cm vs. 115 [13] cm; p = 0.04) and hip (129 [14] cm vs. 125 [13] cm; p = 0.01) circumferences compared to ≤ 1 phenotype.

CONCLUSION

Obesity phenotypes are associated with an additive effect on the body weight and BMI. Patients who have multiple obesity phenotypes may require a more aggressive approach to enhance 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.

Gastroparesis might not be uncommon in patients with diabetes mellitus in a real-world clinical setting: a cohort study

BACKGROUND

This study investigated the frequency of diabetic gastroparesis and associated risk factors in a real-world clinical setting.

METHODS

This retrospective cross-sectional study included patients who underwent assessments of solid gastric emptying time (GET) by technetium-99 m scintigraphy between May 2019 and December 2020. We categorized patients into three groups according to gastric retention of technetium-99 m: rapid (< 65% at 1 h or < 20% at 2 h), normal (≤60% at 2 h and/or ≤ 10% at 4 h), and delayed (> 60% at 2 h and/or > 10% at 4 h).

RESULTS

Patients with diabetes mellitus (DM) were more likely to show abnormal GET than those without DM (119 [70.8%] vs. 16 [44.4%]). The mean glycated A1c was 10.3% in DM patients. DM patients with normal GET were significantly younger (57.2 years, P = 0.044) than those with delayed (65.0 years) or rapid GET (60.2 years). Fasting glucose levels were the lowest in the normal GET group and the highest in the rapid GET group (delayed: 176.3 mg/dL, normal: 151.2 mg/dL, rapid: 181.0 mg/dL, P = 0.030). However, glycated A1c was not significantly different among the delayed, normal, and rapid GET groups in patients with DM. Patients with delayed and rapid GET showed a higher frequency of retinopathy (6.0 vs. 15.5%, P = 0.001) and peripheral neuropathy (11.3 vs. 24.4%, P = 0.001) than those with normal GET. In the multinomial logistic regression analysis, retinopathy demonstrated a positive association with delayed GET, while nephropathy showed a significant negative correlation.

CONCLUSION

DM gastroparesis in the clinical setting was not uncommon. Abnormal GET, including delayed and rapid GET, was associated with DM retinopathy or peripheral neuropathy.

Obesity: A Review of Pathophysiology and Classification

Obesity is a chronic, multifactorial, and morbid disease. In the United States, 69% of adults are overweight or have obesity, and the global prevalence of obesity is increasing. Obesity is influenced by genetic, neurologic, metabolic, enteric, and behavioral processes. It remains a key modifiable risk factor for many comorbid diseases, including cardiovascular disease, diabetes mellitus, and cancer. Whereas there are recent and significant advances in obesity therapy, including diets, lifestyle modifications, pharmacotherapies, endoscopic procedures, and bariatric surgeries, there is an immense need for a better understanding of the heterogeneity in the pathophysiologic process of obesity and outcomes. Here we review salient pathophysiologic mechanisms underlying the development and morbidity of obesity as well as pathophysiologically based classification systems that inform current obesity management and may inform improved and individualized management in the future.

Effect of endoscopic sleeve gastroplasty on gastric emptying, motility and hormones: a comparative prospective study

OBJECTIVE

Endoscopic sleeve gastroplasty (ESG) has gained global adoption but our understanding of its mechanism(s) of action and durability of efficacy is limited. We sought to determine changes in gastric emptying (GE), gastric motility (GM), hormones and eating behaviours after ESG.

DESIGN

A priori-designed single-centre substudy of a large US randomised clinical trial, adults with obesity were randomised to ESG or lifestyle interventions (LS) alone. We measured GE, hormones and weight loss and assessed eating behaviours. In a subset of ESG patients, we assessed GM. The primary outcome was the change in T1/2 (min) at 3 months, and secondary outcomes were changes in weight, GE, GM, hormones and eating behaviours. We used t-test analyses and regression to determine the association between GE and weight loss.

RESULTS

36 (ESG=18; LS=18) participated in this substudy. Baseline characteristics were similar between the two groups. At 3 months, T1/2 was delayed in the ESG group (n=17) compared with the LS group (n=17) (152.3±47.3 vs 89.1±27.9; p<0.001). At 12 months, T1/2 remained delayed in the ESG group (n=16) vs control group (n=14) (137±37.4 vs 90.1±23.4; p<0.001). Greater delays in GE at 3 months were associated with greater weight loss. GM was preserved and fasting ghrelin, glucagon-like peptide 1 and polypeptide YY significantly increased 18 months after ESG.

CONCLUSION

ESG promotes weight loss through several key mechanistic pathways involving GE and hormones while preserving GM. These findings further support clinical adoption of this technique for the management of obesity.

TRIAL REGISTRATION NUMBER

NCT03406975.

Clinical review: Guide to pharmacological management in pediatric obesity medicine

Introduction

Newer pharmacotherapy agents (anti-obesity medication [AOM]) are revolutionizing the management of children and adolescents with obesity. Previously, treatment based on intensive behavioral therapy involved many patient and family contact hours and yielded improvements in obesity status of 1-3 percent of the 95th percentile of the body mass index (BMI). Newer AOMs are yielding more clinically significant improvement of 5-18 percent. This review provides guidance for practitioners in the care of children and adolescents with obesity who frequently have complex medical and behavioral health care needs. Specifically, we discuss the use of newer AOMs in these complex patients.

Methods

This review details an approach to the care of the child and adolescent with obesity using AOMs. A shared decision-making process is presented in which the provider and the patient and family collaborate on care. Management of medical and behavioral components of the disease of obesity in the child are discussed.

Results

Early aggressive treatment is recommended, starting with an assessment of associated medical and behavioral complications, weight promoting medications, use of AOMs and ongoing care. Intensive behavioral therapy is foundational to treatment, but not a specific treatment. Patients and families deserve education on expected outcomes with each therapeutic option.

Conclusions

The use of new AOMs in children and adolescents has changed expected clinical outcomes in the field of pediatric obesity management. Clinically significant improvement in obesity status occurs when AOMs are used early and aggressively. Ongoing, chronic care is the model for optimizing outcomes using a shared decision-making between provider and patient/family. Depending on the experience and comfort level of the primary care practitioner, referral to an obesity medicine specialist may be appropriate, particularly when obesity related co-morbidities are present and pharmacotherapy and metabolic and bariatric surgery are considerations.

Pharmacogenetic interactions of medications administered for weight loss in adults: a systematic review and meta-analysis

Aim: To analyze roles of single nucleotide variants (SNVs) on weight loss with US FDA-approved medications. Materials & methods: We searched the literature up until November 2022. Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines were followed. Results: 14 studies were included in qualitative analysis and seven in meta-analysis. SNVs in CNR1, GLP-1R, MC4R, TCF7L2, CTRB1/2, ADIPOQ, SORCS1 and ANKK1 were evaluated relative to weight loss with glucagon-like peptide-1 agonists (13 studies) or naltrexone-bupropion (one study). CNR1 gene (rs1049353), GLP-1R gene (rs6923761, rs10305420), TCF7L2 gene (rs7903146) were associated with weight loss in at least one study involving glucagon-like peptide-1 agonist(s). The meta-analysis did not identify any consistent effect of SNVs. Conclusion: Pharmacogenetic interactions for exenatide, liraglutide, naltrexone-bupropion and weight loss were identified, but the directionality was inconsistent.

Association Between Food Intake and Gastrointestinal Symptoms in Patients With Obesity

BACKGROUND AND AIMS

Hunger, satiation, postprandial satiety, and hedonic eating constitute key food intake parameters. We aim to study whether these symptoms are associated with gastrointestinal symptoms (GIS) in patients with obesity.

METHODS

This is a cross-sectional study of patients with obesity. Patients completed the following validated biomarkers and questionnaires: hunger was measured via visual analog scale (100 mm) following a standard meal, satiation was measured via ad libitum meal (calories to fullness; kcal), postprandial satiety was measured via gastric emptying scintigraphy (T1/2; mins), and hedonic eating was measured via the Hospital Anxiety and Depression Scale questionnaire. Participants completed the abridged Bowel Disease Questionnaire to evaluate their GIS. We calculated the odds ratios (ORs) adjusted for sex, weight, and age between food intake parameters <25th or >75th percentile observed in a prior cohort of 450 participants with obesity and GIS.

RESULTS

A total of 274 participants (41 ± 10 [SD] years, 75% females, body mass index 39 ± 8 kg/m2) were included in the analysis. Increased hunger was associated with a lower prevalence of lumpy stools (OR = 0.18, P = .02). Satiation was associated with abdominal pain/discomfort (relieved by defecation [OR = 2.4, P = .02] or associated with change in stool consistency [OR = 2.92, P < .01]), loose/watery stools (OR = 2.09, P = .02), and bloating (OR = 2.49, P < .01). Abnormal postprandial satiety was associated with bloating (OR = 2.26, P < .01) and loose/watery stools (OR = 1.84, P = .04). Hedonic eating was associated with abdominal pain/discomfort with stool frequency change (OR = 2.4, P = .02), >3 bowel movements per day (OR = 1.93, P = .048), bloating (OR = 2.49, P = .01), abdominal pain after meals >1 per month (OR = 4.24, P < .01), and nausea >1 per week (OR = 4.51, P < .01).

CONCLUSION

Alterations in hunger, satiation, postprandial satiety, and hedonic eating are associated with GIS in patients with obesity.

Precision Medicine and Obesity

Obesity is a chronic, relapsing, and multifactorial disease, with a rising prevalence and an associated high economic burden. Achieving successful and sustained weight loss outcomes with current interventions is challenging. This is due, at least in part, to the disease's heterogenous pathophysiology that is yet to be completely understood. Technological advances and greater capabilities for the extraction and storage of information have facilitated the application of precision medicine. Several precision medicine initiatives have been proposed to improve obesity outcomes. Most of these initiatives are based on -omics technologies. Although the data generated from these technologies have led to developing hypotheses that may explain the underpinnings of obesity, their applicability to the clinical practice is yet to be determined. There are other initiatives that have identified quantitative or qualitative physiologic traits that can be targeted and that could have a more immediate clinical impact. This review aims to provide a perspective of current initiatives for precision medicine for obesity.

Key Causes and Contributors of Obesity: A Perspective

Obesity is a disease with several potential causes and contributors. This article provides a focused overview of key known causes of obesity and factors that contribute to obesity. Obesity ultimately results from impaired energy storage mechanisms, such as dysregulation of hunger, satiety, digestion, fat storage, and metabolic rate. In addition, myriad contributors promote its expression, including dietary factors, sleep quality and duration, psychological health and well-being, and tobacco cessation, among others. This article concludes with a discussion of the clinical relevance of causes and contributors in obesity prevention and treatment, which is paramount to providing effective, individualized clinical management.

MD, Eckel-Passow J, Acosta A. Precision Medicine for Obesity

Obesity is a multifactorial disease with a variable and underwhelming weight loss response to current treatment approaches. Precision medicine proposes a new paradigm to improve disease classification based on the premise of human heterogeneity, with the ultimate goal of maximizing treatment effectiveness, tolerability, and safety. Recent advances in high-throughput biochemical assays have contributed to the partial characterization of obesity's pathophysiology, as well as to the understanding of the role that intrinsic and environmental factors, and their interaction, play in its development and progression. These data have led to the development of biological markers that either are being or will be incorporated into strategies to develop personalized lines of treatment for obesity. There are currently many ongoing initiatives aimed at this; however, much needs to be resolved before precision obesity medicine becomes common practice. This review aims to provide a perspective on the currently available data of high-throughput technologies to treat obesity.

Association of gastric emptying with postprandial appetite and satiety sensations in obesity

OBJECTIVE

Satiety, defined as the duration of the sensation of fullness, is usually measured by validated visual analog scales (VAS) for appetite. Gastric function plays a key role in food intake regulation. However, the association between gastric emptying (GE) and VAS appetite is unknown.

METHODS

In this cross-sectional study, 134 participants (mean [SEM] age = 39 [0.8] years, mean [SEM] BMI = 38 [0.5] kg/m² , 67% females) completed simultaneous measurements of GE and VAS appetite. After a 320-kcal meal, GE was measured by scintigraphy and appetite by validated 100-mm VAS for 240 minutes. Satiation was defined as calories consumed to terminate meal and was measured by an ad libitum meal. GE, VAS, and ad libitum meal tests were measured on the same day. Percent of meal retention in the stomach, VAS area under curve (AUC_{0-240 min} ), and overall appetite score (OAS) were calculated. Pearson correlation (ρ) determined the association of GE with VAS appetite and satiation. Appetite components were also analyzed by quartiles based on GE_{120 min} .

RESULTS

GE_{120 min} was correlated with sensation of VAS hunger_{AUC(0-240 min)} (ρ = 0.24, p = 0.004), fullness_{AUC(0-240 min)} (ρ = 0.16, p = 0.05), and OAS_{AUC(0-240 min)} (ρ = 0.20, p = 0.02). Patients with rapid GE_{120 min} had a mean increase in VAS hunger_{AUC(0-240 min)} by 32 mm/min (15.62%, p = 0.03) compared with normal/slow GE_{120 min} .

CONCLUSIONS

GE is associated with the sensations of appetite, and rapid GE is associated with increased appetite, which may contribute to weight gain.

Gastric Sensory and Motor Functions and Energy Intake in Health and Obesity-Therapeutic Implications

Sensory and motor functions of the stomach, including gastric emptying and accommodation, have significant effects on energy consumption and appetite. Obesity is characterized by energy imbalance; altered gastric functions, such as rapid gastric emptying and large fasting gastric volume in obesity, may result in increased food intake prior to reaching usual fullness and increased appetite. Thus, many different interventions for obesity, including different diets, anti-obesity medications, bariatric endoscopy, and surgery, alter gastric functions and gastrointestinal motility. In this review, we focus on the role of the gastric and intestinal functions in food intake, pathophysiology of obesity, and obesity management.

Selection of Antiobesity Medications Based on Phenotypes Enhances Weight Loss: A Pragmatic Trial in an Obesity Clinic

OBJECTIVE

Little is known about the predictors of response to obesity interventions.

METHODS

In 450 participants with obesity, body composition, resting energy expenditure, satiety, satiation, eating behavior, affect, and physical activity were measured by validated studies and questionnaires. These variables were used to classify obesity phenotypes. Subsequently, in a 12-month, pragmatic, real-world trial performed in a weight management center, 312 patients were randomly assigned to phenotype-guided treatment or non-phenotype-guided treatment with antiobesity medications: phentermine, phentermine/topiramate, bupropion/naltrexone, lorcaserin, and liraglutide. The primary outcome was weight loss at 12 months.

RESULTS

Four phenotypes of obesity were identified in 383 of 450 participants (85%): hungry brain (abnormal satiation), emotional hunger (hedonic eating), hungry gut (abnormal satiety), and slow burn (decreased metabolic rate). In 15% of participants, no phenotype was identified. Two or more phenotypes were identified in 27% of patients. In the pragmatic clinical trial, the phenotype-guided approach was associated with 1.75-fold greater weight loss after 12 months with mean weight loss of 15.9% compared with 9.0% in the non-phenotype-guided group (difference -6.9% [95% CI -9.4% to -4.5%], P < 0.001), and the proportion of patients who lost >10% at 12 months was 79% in the phenotype-guided group compared with 34% with non-phenotype-guided treatment group.

CONCLUSIONS

Biological and behavioral phenotypes elucidate human obesity heterogeneity and can be targeted pharmacologically to enhance weight loss.

Associations of gastric volumes, ingestive behavior, calorie and volume intake, and fullness in obesity

Whereas gastric emptying significantly predicts calorie intake, the association between gastric capacity and satiation and satiety is unclear. To study the associations between gastric volumes and ingestive behaviors with satiation and satiety in obesity, 62 healthy adult obese patients (57 female) with no eating disorders underwent measurements of satiety, as determined by kilocalories of ingestion at a buffet meal, and satiation by volume to comfortable fullness (VTF) and maximum tolerated volume (MTV), while drinking Ensure (30 mL/min). Fasting and postprandial gastric volumes were measured by validated single-photon emission computed tomography. We also measured eating [Weight Efficacy Life-Style Questionnaire score (WEL)] and exercise behaviors associated with obesity. Spearman correlation-assessed relationships of measured traits and linear regression analysis to identify predictors of satiation or satiety. The participants were aged 38 ± 10.1 yr and the body mass index (BMI) 36.8 ± 4.8 kg/m². Fasting gastric volume was significantly correlated with VTF (r_s = 0.3, P = 0.03), but not with MTV or buffet meal kilocalorie ingestion. Regression analysis identified sex (P = 0.02, with males having significantly higher fasting gastric volume) and fasting gastric volume (0.04) as predictors of higher VTF. An increase in fasting gastric volume of 50 mL resulted in a 6-mL increase in VTF. Buffet meal intake was inversely related to the ability to resist the urge to eat; factors associated with ingestive behavior (increase in total WEL score) significantly correlated with satiety and gastric accommodation (P < 0.05). Gastric capacity during fasting is associated with calorie intake to the point of comfortable fullness; factors associated with ingestive behavior are associated with satiety and gastric accommodation.NEW & NOTEWORTHY Buffet meal intake was inversely related to the ability to resist the urge to overeat. Factors associated with ingestive behavior significantly correlated with satiety and gastric accommodation. Gastric capacity during fasting is associated with calorie intake to the point of comfortable fullness; factors associated with ingestive behavior are associated with satiety and gastric accommodation.