A new wave of weight-loss therapies aims to be better than today’s GLP-1s
The modern era of anti-obesity medicine has been defined by GLP-1 receptor agonists. Drugs such as semaglutide and tirzepatide have normalized double‑digit percentage weight loss for many people with obesity, and they are beginning to show benefits that matter clinically—fewer cardiovascular events, improvements in sleep apnea, and relief of symptoms in heart failure with preserved ejection fraction. Yet this first wave is not the endpoint. Across pharma and biotech, a second generation of therapies is being engineered to deliver greater weight loss, better tolerability, simpler dosing, broader health benefits, and—eventually—lower cost and easier access.
Where today’s GLP-1s stand
– What they do well:
– Efficacy: Weekly injectable GLP-1s (for example, semaglutide) commonly yield average weight losses around the mid-teens percent over a year or more. Dual-agonists that add GIP activity (tirzepatide) push into the 20% range in some studies.
– Hard outcomes: Semaglutide has demonstrated cardiovascular risk reduction in people with established heart disease. Tirzepatide has improved apnea–hypopnea index in sleep apnea, supporting label expansion.
– Metabolic health: These agents reduce liver fat, lower A1C and blood pressure, and improve lipid profiles.
– What holds them back:
– Side effects and dropouts: Nausea, vomiting, diarrhea, and constipation are common, particularly during dose escalation. A minority stop therapy because of symptoms.
– Lean mass loss: A meaningful share of weight lost is lean tissue without deliberate resistance training and adequate protein intake.
– Plateaus and persistence: Weight loss often plateaus. Stopping the drug typically leads to weight regain.
– Access frictions: High cost, supply constraints, and insurance hurdles limit uptake. Injections deter some patients.
– Safety questions that need long follow-up: Gallbladder disease, rare pancreatitis, potential retinopathy worsening in rapidly improving diabetes, and the class boxed warning related to C‑cell tumors in rodents.
What “better than GLP‑1s” looks like
Companies are targeting several dimensions of improvement:
– Greater potency, approaching bariatric‑surgery‑like weight loss for more patients (25–30% and beyond)
– Fewer gastrointestinal side effects with gentler titration or receptor “balancing”
– Preservation of lean mass and functional capacity
– Oral, once‑daily pills or even longer‑interval injectables (for example, monthly)
– Stronger effects on comorbidities: fatty liver disease, sleep apnea, heart and kidney disease
– Faster onset and more durable maintenance
– Lower manufacturing complexity and cost to expand access globally
The next wave: key scientific strategies
1) Multi-agonists that recruit more than GLP‑1
– GLP‑1/GIP/Glucagon triple agonists: By engaging receptors that suppress appetite (GLP‑1, GIP) and increase energy expenditure and fat oxidation (glucagon), triple agonists have delivered some of the largest weight-loss signals seen in mid‑stage trials, with average losses pushing into the mid‑20% range over roughly a year. The glucagon “dial” also appears to deepen liver fat reduction, potentially benefiting metabolic dysfunction–associated steatohepatitis (MASH).
– GLP‑1/Glucagon duals: Co‑agonists in this class have produced high‑teens average weight loss and notable reductions in liver fat in Phase 2 studies. Several are being advanced explicitly for obesity with fatty liver disease.
– Next‑gen GLP‑1/GIP modulators: Tirzepatide proved that combining GIP signaling with GLP‑1 can lift efficacy and, in some patients, improve GI tolerability. New entrants vary the balance between agonism and antagonism at the GIP receptor and aim for less nausea, longer dosing intervals, or both. Some candidates are designed for once‑monthly injections.
2) Targeting the amylin pathway—alone and in combinations
– Amylin analogs: Amylin is a pancreatic hormone that complements GLP‑1 by promoting satiety and slowing gastric emptying. Modern amylin analogs with long half‑lives are in mid‑to‑late development, both as monotherapy and in fixed‑dose combinations with GLP‑1s.
– GLP‑1 plus amylin combinations: Pairing a GLP‑1 with an amylin analog has shown additive effects—greater average weight loss than either alone in early trials. A co‑formulated GLP‑1/amylin product is now in Phase 3, and single‑molecule GLP‑1–amylin co‑agonists (engineered peptides that hit both receptors) have posted striking early signals, with unusually rapid reductions in body weight over just a few months.
3) Oral small‑molecule incretin mimetics
– Non‑peptide GLP‑1 receptor agonists: Unlike oral semaglutide, which is still a peptide that needs an absorption enhancer, these are true small molecules that can be manufactured at scale as conventional pills. Mid‑stage data for the leading program showed double‑digit average weight loss with once‑daily oral dosing, and large Phase 3 programs are underway.
– Other oral programs: Several companies are advancing alternative oral GLP‑1 designs or entirely different small‑molecule approaches to the same pathway. While some early compounds have struggled with tolerability, reformulations and next‑gen structures continue to progress.
4) Making treatment easier to live with
– Gentler dose escalation and receptor “bias”: Molecules that minimize the GI discomfort associated with GLP‑1 while preserving appetite suppression are in development. Balancing co‑agonist activity appears to help.
– Longer‑acting depots: Beyond weekly injections, some programs are aiming for once‑monthly dosing with comparable efficacy.
– Smarter maintenance: Trials are testing lower “maintenance” doses or intermittent schedules after initial weight loss, as well as digital tools and nutrition/exercise support designed alongside the drug to preserve lean mass and reduce relapse.
5) Beyond weight: directly targeting comorbidities
– Fatty liver disease (MASH): Because glucagon activity reduces liver fat and GLP‑1 improves insulin resistance, multi‑agonists are being evaluated for histologic endpoints in MASH. Early signals include fibrosis improvement alongside weight loss.
– Cardiovascular and renal outcomes: Next‑gen agents will be run through large outcomes trials, following the template set by diabetes and the first GLP‑1 obesity CVOT. Some programs are also exploring heart failure symptoms, blood pressure, kidney function, and sleep apnea as primary endpoints.
Open questions and trade‑offs
– Tolerability versus potency: Adding receptors tends to increase efficacy but can bring new side effects (for example, more pronounced heart rate increases or GI symptoms). Getting the “balance” right is central to drug design.
– Lean mass preservation: Lifestyle measures remain the proven lever. Drug combinations that spare or build muscle—such as pairing weight‑loss agents with myostatin/activin pathway inhibitors—are scientifically appealing, but clinical evidence is still early.
– Durability and discontinuation: Most agents still require ongoing use to maintain weight loss. Research into maintenance strategies and relapse‑prevention dosing is active.
– Safety over years, not months: As with first‑wave GLP‑1s, rare risks (gallbladder events, pancreatitis) and class warnings will be tracked in larger, longer studies. Reassuring long‑term safety is essential for chronic use.
– Equity and access: Small‑molecule orals could cut costs and ease manufacturing bottlenecks. Until then, prices, coverage policies, and supply constraints will shape who benefits.
Who’s advancing what
– Eli Lilly: Building beyond tirzepatide with an oral non‑peptide GLP‑1 in Phase 3 and a triple agonist in late development that has shown some of the largest weight‑loss signals to date.
– Novo Nordisk: Advancing an amylin analog and a fixed‑dose GLP‑1/amylin combo in Phase 3, and a single‑molecule GLP‑1–amylin co‑agonist with potent early data. Higher‑potency and longer‑acting GLP‑1s are also in the works.
– Amgen: A long‑acting incretin modulator designed for monthly dosing has demonstrated substantial weight loss in early studies, alongside an oral GLP‑1 program.
– Boehringer Ingelheim/Zealand: A GLP‑1/glucagon co‑agonist has produced high‑teens weight loss and strong liver fat reductions and is being developed for both obesity and MASH.
– Altimmune, Viking and others: Multiple GLP‑1/glucagon or GLP‑1/GIP programs—both injectables and orals—are advancing through mid‑stage trials with competitive efficacy.
Timelines and what to watch next
– 2025–2027 is the likely window for the first approvals among the next wave, starting with GLP‑1/amylin combinations and possibly the first oral non‑peptide GLP‑1s.
– Triple agonists could follow if Phase 3 confirms their impressive Phase 2 efficacy while keeping side effects manageable.
– Expect more data tying weight‑loss drugs to disease modification—resolution of MASH, fewer hospitalizations for heart failure, sustained improvements in sleep apnea—and health‑economic evidence that supports broader reimbursement.
– Manufacturing scale‑up and the arrival of true small‑molecule orals will influence pricing, availability, and global access.
Bottom line
GLP‑1s changed what’s possible in medical weight loss, but they also exposed the field’s remaining gaps: tolerability, maintenance, muscle preservation, convenience, cost, and comprehensive disease control. The next generation of therapies is being designed to close those gaps. Multi‑agonists that combine GLP‑1 with GIP, glucagon, or amylin aim to push average weight loss into the range once associated only with surgery, while amplifying benefits in the liver, heart, and lungs. Oral small molecules could democratize access. Success will depend not just on more pounds lost, but on safer, more livable treatment over years, and on delivering broad metabolic health gains that matter to patients, clinicians, and payers alike.
