GLP-1 in diabetes care: Can glycemic control be achieved without nausea and vomiting?

Subthreshold activation of the melanocortin system causes generalized sensitization to anorectic agents in mice

The melanocortin-3 receptor (MC3R) regulates GABA release from agouti-related protein (AgRP) nerve terminals and thus tonically suppresses multiple circuits involved in feeding behavior and energy homeostasis. Here, we examined the role of the MC3R and the melanocortin system in regulating the response to various anorexigenic agents. The genetic deletion or pharmacological inhibition of the MC3R, or subthreshold doses of an MC4R agonist, improved the dose responsiveness to glucagon-like peptide 1 (GLP1) agonists, as assayed by inhibition of food intake and weight loss. An enhanced anorectic response to the acute satiety factors peptide YY (PYY3-36) and cholecystokinin (CCK) and the long-term adipostatic factor leptin demonstrated that increased sensitivity to anorectic agents was a generalized result of MC3R antagonism. We observed enhanced neuronal activation in multiple hypothalamic nuclei using Fos IHC following low-dose liraglutide in MC3R-KO mice (Mc3r-/-), supporting the hypothesis that the MC3R is a negative regulator of circuits that control multiple aspects of feeding behavior. The enhanced anorectic response in Mc3r-/- mice after administration of GLP1 analogs was also independent of the incretin effects and malaise induced by GLP1 receptor (GLP1R) analogs, suggesting that MC3R antagonists or MC4R agonists may have value in enhancing the dose-response range of obesity therapeutics.

Reductions of food intake and body weight in diet-induced obese rats following chronic treatment with a monomeric peptide multiagonist

INTRODUCTION

While therapies based on endogenous gut peptides such as glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) have been compelling therapeutic agents for obesity and type 2 diabetes (T2D), only a few have achieved long-term weight loss and all have shown significant side-effects, including nausea/malaise and gastrointestinal ailments.

OBJECTIVE

As the pathophysiology of obesity is driven by dysregulation of multiple, inter-related, pathways, we tested a novel peptide targeting multiple receptors of complementary neurocircuits regulating the controls of energy balance.

METHODS

Response to daily injections of GEP44, a GLP-1R and neuropeptide Y1R and Y2R receptor (Y1R/Y2R) triple agonist was tested vs. the GLP-1R agonist liraglutide (LIRA) in diet-induced obese (DIO) male and female rats. Glucose tolerance tests after intraperitoneal injection of glucose (IPGTT) were performed at baseline and after 14-d of treatment in GEP44 treated rats. Other metabolic parameters were assessed in blood at the end of a 28-d intervention.

RESULTS

Upon conclusion at 28-d, body weight reduction compared to vehicle was -15.6%/-11.9% in response to GEP44, vs. -9.7%/-5.1% after LIRA, males, and females, respectively. Significant reductions of cumulative food intake occurred over 28-d in female rats treated with GEP44 (-30%; p < 0.0001), vs. LIRA (-10%), and in male rats GEP44 (-39%; p < 0.0001), vs. LIRA (-20%; p = 0.003). In IPGTTs, a similar stimulation glucose induced insulin secretion was noted in rats treated with GEP44 and LIRA.

CONCLUSION

The strong reductions of body weight in response to long-term applications of the triple agonist GEP44 confirms the therapeutic potential of targeting multiple receptors for achieving more robust and potentially more sustained improvement of energy balance.

Sustained metabolic benefits of ΔTRTX-Ac1, a tarantula venom-derived peptide, when administered together with exenatide in high-fat fed mice

AIM

The aim of the present study was to assess the long-term therapeutic efficacy of a recently discovered 28 amino acid peptide, Δ-theraphotoxin-Ac1 (Δ-TRTX-Ac1), originally isolated from venom of the Aphonopelma chalcodes tarantula. Δ-TRTX-Ac has previously been shown to improve pancreatic beta-cell function and suppress appetite.

MATERIALS AND METHODS

Δ-TRTX-Ac1 was administered twice daily in high-fat fed (HFF) mice with streptozotocin (STZ)-induced insulin deficiency, namely HFF/STZ mice, for 28 days both alone and in combination with the venom-derived glucagon-like peptide-1 (GLP-1) mimetic, exenatide.

RESULTS

Initial pharmacokinetic profiling of ΔTRTX-Ac1 revealed a plasma half-life of 2 h in mice, with ΔTRTX-Ac1 also evidenced in the pancreas 12 h post-injection. Accordingly, HFF-STZ mice received twice-daily injections of Δ-TRTX-Ac1, exenatide or a combination of both peptides for 28 days. As anticipated, HFF/STZ mice presented with hyperglycaemia, impaired glucose tolerance, decreased plasma and pancreatic insulin and disturbed pancreatic islet morphology. Administration of ΔTRTX-Ac1 reduced body weight, improved glucose tolerance and augmented pancreatic insulin content while decreasing glucagon content. Exenatide had similar benefits on body weight and pancreatic hormone content while also reducing circulating glucose. ΔTRTX-Ac1 decreased energy expenditure on day 28 whereas exenatide had no impact. All treatment regimens restored pancreatic islet and beta-cell area towards lean control levels, which was linked to significantly elevated beta-cell proliferation rates. In terms of benefits of combined ΔTRTX-Ac1 and exenatide treatment over individual agents, there was augmentation of glucose tolerance and ambulatory activity with combination therapy, and these mice presented with increased pancreatic glucagon.

CONCLUSION

These data highlight the therapeutic promise of ΔTRTX-Ac1 for diabetes, with suggestion that benefits could be enhanced through combined administration with exenatide.

Inhibition of the melanocortin-3 receptor (MC3R) causes generalized sensitization to anorectic agents

The melanocortin-3 receptor (MC3R) acts presynaptically to regulate GABA release from agouti-related protein (AgRP) nerve terminals and thus may be a negative regulator of multiple circuits involved in feeding behavior and energy homeostasis. Here, we examined the role of MC3R in regulating the response to various anorexigenic agents. Our findings reveal that genetic deletion or pharmacological inhibition of MC3R improves the dose responsiveness to Glucagon-like peptide 1 (GLP1) agonists, as assayed by inhibition of food intake and weight loss. An enhanced anorectic response to other agents, including the acute satiety factors peptide YY (PYY3-36) and cholecystokinin (CCK) and the long-term adipostatic factor, leptin, demonstrated that increased sensitivity to anorectic agents is a generalized result of MC3R antagonism. Enhanced neuronal activation in multiple nuclei, including ARH, VMH, and DMH, was observed using Fos immunohistochemistry following low-dose liraglutide in MC3R knockout mice (Mc3r-/-), supporting the hypothesis that the MC3R is a negative regulator of circuits regulating multiple aspects of feeding behavior. The enhanced anorectic response in Mc3r -/- mice after administration of GLP1 analogs was also independent of the incretin effects and malaise induced by GLP1R analogs, suggesting that MC3R antagonists may have value in enhancing the dose-response range of obesity therapeutics.

NASH Drug Development: Seeing the Light at the End of the Tunnel?

Nonalcoholic steatohepatitis (NASH) is a chronic liver disease affecting a large population worldwide. No clinically approved drugs are available. In this minireview, we discuss the heterogeneous nature of NASH and lack of consensus in outcome measures among clinical trials. We summarize NASH therapeutic targets and candidate drugs. We compare the efficacy of 33 published clinical trials that evaluated noninvasive biomarkers and liver biopsy. Currently, phase II trial results of fibroblast growth factor 21 (FGF21) and phase III trial results of resmetirom and pioglitazone are encouraging.

The locus coeruleus contributes to the anorectic, nausea, and autonomic physiological effects of glucagon-like peptide-1

Increasing the therapeutic potential and reducing the side effects of U.S. Food and Drug Administration-approved glucagon-like peptide-1 receptor (GLP-1R) agonists used to treat obesity require complete characterization of the central mechanisms that mediate both the food intake-suppressive and illness-like effects of GLP-1R signaling. Our studies, in the rat, demonstrate that GLP-1Rs in the locus coeruleus (LC) are pharmacologically and physiologically relevant for food intake control. Furthermore, agonism of LC GLP-1Rs induces illness-like behaviors, and antagonism of LC GLP-1Rs can attenuate GLP-1R-mediated nausea. Electrophysiological and behavioral pharmacology data support a role for LC GLP-1Rs expressed on presynaptic glutamatergic terminals in the control of feeding and malaise. Collectively, our work establishes the LC as a site of action for GLP-1 signaling and extends our understanding of the GLP-1 signaling mechanism necessary for the development of improved obesity pharmacotherapies.

Tirzepatide-Induced Gastrointestinal Manifestations: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis determine how frequently and how seriously gastrointestinal manifestations affect people with type 2 diabetes mellitus on tirzepatide. Tirzepatide is a recently developed drug that attempts to enhance type 2 diabetics' ability to regulate their blood sugar levels and promote weight reduction. Despite its potential benefits, clinical trials have revealed that the medication may lead to gastrointestinal side effects, including nausea, vomiting, decreased appetite, dyspepsia, constipation, and diarrhea. These side effects may negatively affect the drug's efficacy and patient tolerance. A comprehensive search of electronic databases such as PubMed, Web of Science, and Cochrane Library, was conducted to find pertinent studies reporting on the frequency and severity of gastrointestinal symptoms in type 2 diabetes patients receiving tirzepatide. This systematic review follows the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Study selection, data extraction, and quality assessment were performed. Six randomized controlled trials with a total of 4,586 patients were included. Most patients received tirzepatide to regulate their blood sugar levels and promote weight reduction, and the comparators were placebo, glucagon-like peptide one receptor agonists drugs, and insulin degludec. The dose of tirzepatide was 5mg, 10mg, and 15mg weekly. The incidence rate of nausea in patients who receive tirzepatide was 20.43%, while the incidence rate in the comparators was 10.47%, and it was significantly higher in the tirzepatide arm than in the comparators (RR, 2.90; 95% CI, 1.89 to 4.44; P ≤ 0.00001). The incidence rate of vomiting in patients who receive tirzepatide was 9.05%, while the rate in the comparators was 4.86%, and it was significantly higher in the tirzepatide arm than in the comparators (RR, 2.69; 95% CI, 1.67 to 4.36; P ≤ 0.0001). The incidence rate of constipation in patients who receive tirzepatide was 2.54%, while the rate in the comparators was 0.856%, and it was significantly higher in the tirzepatide arm than in the comparators (RR, 3.08; 95% CI, 1.83 to 5.20; P ≤ 0.0001). The incidence rate of decreased appetite in patients who receive tirzepatide was 9.64%, while the rate in the comparators was 2.88%, and it was significantly higher in the tirzepatide arm than in the comparators (RR, 5.04; 95% CI, 3.01 to 8.45; P ≤ 0.00001). The incidence rate of diarrhea in patients who receive tirzepatide was 16.24%, while the rate in the comparators was 8.63%, and it was significantly higher in the tirzepatide arm than in the comparators (RR, 2.07; 95% CI, 1.60 to 2.68; P ≤ 0.00001). The incidence rate of dyspepsia in patients who receive tirzepatide was 7.13%, while the rate in the comparators was 3.31%, and it was significantly higher in the tirzepatide arm than in the comparators (RR, 2.52; 95% CI, 1.58 to 4.01; P ≤ 0.0001). Tirzepatide usage is linked to a significant prevalence of gastrointestinal symptoms, including nausea, constipation, decreased appetite, dyspepsia, diarrhea, and vomiting, in people with type 2 diabetes. These findings may influence clinical decision-making and patient counseling on the use of tirzepatide and have significant implications for the medication's tolerance and efficacy. To find ways to reduce these negative effects and improve therapy for type 2 diabetes patients, more research is required.

A peptide triple agonist of GLP-1, neuropeptide Y1, and neuropeptide Y2 receptors promotes glycemic control and weight loss

Mechanisms underlying long-term sustained weight loss and glycemic normalization after obesity surgery include changes in gut hormone levels, including glucagon-like peptide 1 (GLP-1) and peptide YY (PYY). We demonstrate that two peptide biased agonists (GEP44 and GEP12) of the GLP-1, neuropeptide Y1, and neuropeptide Y2 receptors (GLP-1R, Y1-R, and Y2-R, respectively) elicit Y1-R antagonist-controlled, GLP-1R-dependent stimulation of insulin secretion in both rat and human pancreatic islets, thus revealing the counteracting effects of Y1-R and GLP-1R agonism. These agonists also promote insulin-independent Y1-R-mediated glucose uptake in muscle tissue ex vivo and more profound reductions in food intake and body weight than liraglutide when administered to diet-induced obese rats. Our findings support a role for Y1-R signaling in glucoregulation and highlight the therapeutic potential of simultaneous receptor targeting to achieve long-term benefits for millions of patients.

Does glucose lowering restore GIP effects on insulin secretion?

AIMS

Some studies have shown that in type 2 diabetic patients the potentiation of insulin secretion by glucose-dependent insulinotropic polypeptide (GIP) is compromised but can be partially restored if glucose is lowered. Renewed interest for this phenomenon has been expressed in the context of the new dual GIP-GLP-1 (glucagon-like peptide-1) receptor agonists, which have shown greater efficacy of this drug class compared with single GLP-1 receptor agonists, including on insulin secretion. However, contrasting evidence has been reported on the recovery of GIP action with glucose lowering. In our study, we reconsider all publications relevant for the problem and analyze the results using a uniform methodology.

DATA SYNTHESIS

We show that, while some contradictions might be explained by heterogeneous analysis methods, it is possible to interpret all the available data coherently and conclude that the effect of glucose lowering is relevant only when glucose concentration is virtually normalized.

CONCLUSIONS

While a significant restoration of GIP action may not occur with some traditional diabetes treatments, GIP action improvement might become relevant when glucose is virtually normalized and could explain part of the success of the double GIP-GLP-1 receptor agonists.

Weight loss efficiency and safety of tirzepatide: A Systematic review

OBJECTIVE

Tirzeptide is a novel glucagon-like peptide-1 receptor (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) drug, which shows good efficiency for weight loss. Therefore, we aim to investigate the efficacy and safety of tirzepatide for weight loss in type 2 diabetes mellitus (T2DM) and obesity patients in this meta-analysis study.

METHODS

Cochrane Library, PubMed, Embase, Clinical Trials, and Web of Science were searched from inception to October 5, 2022. All randomized controlled trials (RCTs) were included. The odds ratio (OR) was calculated using fixed-effects or random-effects models by Review Manager 5.3 software.

RESULTS

In total, ten studies (12 reports) involving 9,873 patients were identified. A significant loss body weight in the tirzepatide group versus the placebo by -9.81 kg (95% CI (-12.09, -7.52), GLP-1 RAs by -1.05 kg (95% CI (-1.48, -0.63), and insulin by -1.93 kg (95% CI (-2.81, -1.05), respectively. In sub-analysis, the body weight of patients was significantly reduced in three tirzepatide doses (5 mg, 10 mg, and 15 mg) when compared with those of the placebo/GLP-1 RA/insulin. In terms of safety, the incidence of any adverse events and adverse events leading to study drug discontinuation was higher in the tirzepatide group, but the incidence of serious adverse events and hypoglycaemia was lower. Additionally, the gastrointestinal adverse events (including diarrhea, nausea, vomiting and decreased appetite) of tirzepatide were higher than those of placebo/basal insulin, but similar to GLP-1 RAs.

CONCLUSION

In conclusion, tirzeptide can significantly reduce the weight of T2DM and patient with obesity, and it is a potential therapeutic regimen for weight-loss, but we need to be vigilant about its gastrointestinal reaction.

The efficacy of GLP-1RAs for the management of postprandial hypoglycemia following bariatric surgery: a systematic review

OBJECTIVE

Postprandial hyperinsulinemic hypoglycemia with neuroglycopenia is an increasingly recognized complication of Roux-en-Y gastric bypass and gastric sleeve surgery that may detrimentally affect patient quality of life. One likely causal factor is glucagon-like peptide-1 (GLP-1), which has an exaggerated rise following ingestion of carbohydrates after bariatric surgery. This paper sought to assess the role of GLP-1 receptor agonists (GLP-1RAs) in managing postprandial hypoglycemia following bariatric surgery.

METHODS

MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and Scopus were systematically and critically appraised for all peer-reviewed publications that suitably fulfilled the inclusion criteria established a priori. This systematic review was developed according to the Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols (PRISMA-P). It followed methods outlined in the Cochrane Handbook for Systematic Reviews of Interventions and is registered with PROSPERO (International Prospective Register of Systematic Reviews; identifier CRD420212716429).

RESULTS AND CONCLUSIONS

Postprandial hyperinsulinemic hypoglycemia remains a notoriously difficult to manage metabolic complication of bariatric surgery. This first, to the authors' knowledge, systematic review presents evidence suggesting that use of GLP-1RAs does not lead to an increase of hypoglycemic episodes, and, although this approach may appear counterintuitive, the findings suggest that GLP-1RAs could reduce the number of postprandial hypoglycemic episodes and improve glycemic variability.

The past, present, and future physiology and pharmacology of glucagon

The evolution of glucagon has seen the transition from an impurity in the preparation of insulin to the development of glucagon receptor agonists for use in type 1 diabetes. In type 2 diabetes, glucagon receptor antagonists have been explored to reduce glycemia thought to be induced by hyperglucagonemia. However, the catabolic actions of glucagon are currently being leveraged to target the rise in obesity that paralleled that of diabetes, bringing the pharmacology of glucagon full circle. During this evolution, the physiological importance of glucagon advanced beyond the control of hepatic glucose production, incorporating critical roles for glucagon to regulate both lipid and amino acid metabolism. Thus, it is unsurprising that the study of glucagon has left several paradoxes that make it difficult to distill this hormone down to a simplified action. Here, we describe the history of glucagon from the past to the present and suggest some direction to the future of this field.

Knocking on GDF15's door for the treatment of type 2 diabetes mellitus

Although a large number of drugs are available for the treatment of type 2 diabetes mellitus (T2DM), many patients do not achieve adequate disease control despite adhering to medication. Recent findings indicate that the pharmacological modulation of the stress-induced cytokine growth differentiation factor 15 (GDF15) shows promise for the treatment of T2DM. GDF15 suppresses appetite and reduces inflammation, increases thermogenesis and lipid catabolism, sustains AMP-activated protein kinase (AMPK) activity, and ameliorates insulin resistance and hepatic steatosis. In addition, circulating GDF15 levels are elevated in response to several antidiabetic drugs, including metformin, with GDF15 mediating some of their effects. Here, we review the mechanistic insights into the beneficial effects of recently explored therapeutic approaches that target GDF15 for the treatment of T2DM.

Optimal dose of tirzepatide for type 2 diabetes mellitus: A meta-analysis and trial sequential analysis

Objective

The purpose of this study is to evaluate the optimal dose of tirzepatide (TZP) for the treatment of type 2 diabetes mellitus (T2DM) by meta-analysis and trial sequential analysis (TSA).

Methods

Clinical trials of TZP for T2DM were obtained by searching 8 databases with a time limit from database creation to May 2022. Mean differences (MD) and 95% confidence intervals (95%CI) were used for continuous variables, and relative risk (RR) and 95%CI were used for dichotomous variables.

Results

Compared with TZP 5 mg, meta-analysis showed that TZP 10 mg significantly reduced glycosylated hemoglobin type A1c (HbA1c) (MD −0.24, 95%CI −0.31~-0.17, P &lt; 0.00001), fasting serum glucose (FSG) (MD −5.82, 95%CI −8.35~-3.28, P &lt; 0.00001) and weight (MD −2.47, 95%CI −2.95~-1.98, P &lt; 0.00001), and TZP 15 mg significantly reduced HbA1c (MD −0.37, 95%CI −0.44~-0.29, P &lt; 0.00001), FSG (MD −8.52, 95%CI −11.07~-5.98, P &lt; 0.00001) and weight (MD −4.63, 95%CI −5.45~-3.81, P &lt; 0.00001). Compared with TZP 10 mg, TZP 15 mg dramatically reduced HbA1c (MD −0.12, 95%CI −0.19~-0.05, P = 0.001), FSG (MD −2.73, 95%CI −5.29~-0.17, P = 0.04) and weight (MD −2.18, 95%CI −2.67~-1.70, P &lt; 0.00001). The TSA indicated that the benefits observed in the current information set were conclusive, except for the FSG of “TZP 15 mg vs. TZP 10 mg”. In terms of safety endpoints, meta-analysis revealed that there was no significant difference in the serious adverse events (AEs), major adverse cardiovascular events-4 (MACE-4), cardiovascular death, hypertension, cancer and hypoglycemic of the three dose groups of TZP. Compared with TZP 5 mg, TZP 10 mg increased total adverse events (RR 1.06, 95%CI 1.01~1.11, P = 0.03) and gastrointestinal (GI) AEs (RR 1.17, 95%CI 1.03~1.33, P = 0.02), and TZP 15 mg increased total AEs (RR 1.10, 95%CI 1.05~1.15, P = 0.0001). There were no significant differences in total AEs and GI AEs for TZP 15 mg compared to TZP 10 mg. The TSA demonstrated that the total AEs of “TZP 15 mg vs. TZP 5 mg” were conclusive.

Conclusions

TZP 15 mg &gt;TZP 10 mg &gt; TZP 5 mg in terms of lowering glycemia and reducing weight. TZP 5 mg &gt; TZP 10 mg = TZP 15 mg in terms of safety. On this basis, we recommend TZP 5 mg as the first-choice dose for patients with T2DM to minimize AEs while reducing glycemia and weight. If patients cannot effectively control their glycemia after taking TZP 5 mg, it is recommended to take TZP 15 mg directly to achieve the best effect of glycemic reduction. However, most of the included studies have the background of basic medication, the independent efficacy and safety of different doses of TZP still need to be tested.

Systematic review registration

Unique Identifier: CRD42022341966.

Emetic Response to T-2 Toxin Correspond to Secretion of Glucagon-like Peptide-17–36 Amide and Glucose-Dependent Insulinotropic Polypeptide

The T-2 toxin, a major secondary metabolite of Fusarium Gramineae, is considered a great risk to humans and animals due to its toxicity, such as inducing emesis. The mechanism of emesis is a complex signal involving an imbalance of hormones and neurotransmitters, as well as activity of visceral afferent neurons. The T-2 toxin has been proven to induce emesis and possess the capacity to elevate expressions of intestinal hormones glucagon-like peptide-_17–36 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), both of which are important emetic factors. In addition, the activation of calcium-sensitive receptor (CaSR) and transient receptor potential (TRP) channels are engaged in intestinal hormone release. However, it is unknown whether hormones GLP-1 and GIP mediate T-2 toxin-induced emetic response through activating CaSR and TRP channels. To further assess the mechanism of T-2 toxin-induced emesis, we studied the hypothesis that T-2 toxin-caused emetic response and intestinal hormones GLP-1 and GIP released in mink are associated with activating calcium transduction. Following oral gavage and intraperitoneal injection T-2 toxin, emetic responses were observed in a dose-dependent manner, which notably corresponded to the secretion of GLP-1 and GIP, and were suppressed by pretreatment with respective antagonist Exending_9–39 and Pro3GIP. Additional research found that NPS-2143 (NPS) and ruthenium red (RR), respective antagonists of CaSR and TRP channels, dramatically inhibited both T-2 toxin-induced emesis response and the expression of plasma GLP-1 and GIP. According to these data, we observed that T-2 toxin-induced emetic response corresponds to secretion of GLP-1 and GIP via calcium transduction.

GDF15 in Appetite and Exercise: Essential Player or Coincidental Bystander?

Growth differentiation factor 15 (GDF15) has recently moved to the forefront of metabolism research. When administered pharmacologically, GDF15 reduces food intake and lowers body weight via the hindbrain-situated receptor GFRAL (glial cell-derived neurotrophic factor family receptor alpha-like). Endogenous GDF15 is a ubiquitous cellular stress signal that can be produced and secreted by a variety of cell types. Circulating levels are elevated in a series of disease states, but also in response to exogenous agents such as metformin, colchicine, AICAR, and cisplatin. Recently, exercise has emerged as a relevant intervention to interrogate GDF15 physiology. Prolonged endurance exercise increases circulating GDF15 to levels otherwise associated with certain pathological states and in response to metformin treatment. The jury is still out on whether GDF15 is a functional "exerkine" mediating organ-to-brain crosstalk or whether it is a coincidental bystander. In this review, we discuss the putative physiological implication of exercise-induced GDF15, focusing on the potential impact on appetite and metabolism.