Mazdutide and tirzepatide are both injectable, once-weekly weight-loss drugs built on the incretin hormone system, but they pull different metabolic levers. Tirzepatide activates receptors for GIP and GLP-1, while mazdutide targets GLP-1 and glucagon receptors. That distinction shapes how each drug affects appetite, energy expenditure, and liver fat, and it may ultimately determine which patients benefit most from each one. The clinical evidence so far is deeper for tirzepatide, which has large phase 3 trials in diverse populations and regulatory approval in several countries, while mazdutide’s strongest data come from Chinese trial populations and are still accumulating.
Two Different Receptor Combinations
Both drugs belong to the broader family of incretin-based therapies, meaning they mimic gut hormones that help regulate blood sugar, appetite, and metabolism. But they are not twins. Tirzepatide is a dual GIP and GLP-1 receptor agonist. Research characterizes it as “imbalanced,” leaning more heavily on GIP receptor activity while also producing distinct signaling at the GLP-1 receptor, a combination thought to explain its strong effects on both insulin secretion and weight.1JCI Insight. Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonist GIP has been linked to fat tissue metabolism and nutrient sensing, which may contribute to tirzepatide’s ability to produce substantial fat-mass loss beyond what GLP-1 drugs achieve alone.
Mazdutide takes a different approach. It is an analogue of oxyntomodulin, a naturally occurring gut hormone that activates both GLP-1 and glucagon receptors.2PubMed Central. Safety and efficacy of a GLP-1 and glucagon receptor dual agonist mazdutide (IBI362) 9 mg and 10 mg in Chinese adults with overweight or obesity While GLP-1 receptor activation suppresses appetite and slows gastric emptying (the same mechanism behind semaglutide), the glucagon receptor side of mazdutide adds something GLP-1-only drugs lack. Glucagon boosts resting metabolic rate, stimulates the liver to burn fatty acids, and reduces the liver’s production of new fat.3PubMed Central. Oxyntomodulin physiology and its therapeutic development in obesity and associated complications In theory, this means mazdutide attacks excess weight from two directions: reduced calorie intake through GLP-1 and increased calorie burning through glucagon.
The clinical question is whether that theoretical advantage translates into better real-world outcomes, or whether tirzepatide’s GIP-driven mechanism achieves comparable or even greater results through a different route. The trial data available so far give a partial answer.
Weight Loss in Head-to-Head Context
No published trial has directly compared mazdutide and tirzepatide in the same patient population. That makes any comparison indirect and approximate, requiring caution about differences in trial design, dosing schedules, participant demographics, and treatment duration. Still, the numbers from each drug’s phase 3 trials paint a useful picture.
Tirzepatide’s landmark SURMOUNT-1 trial enrolled over 2,500 adults with obesity or overweight (without diabetes) and ran for 72 weeks. At the highest dose of 15 mg weekly, participants lost an average of about 21% of their body weight, while the 10 mg dose produced roughly a 20% loss and the 5 mg dose about 15%. More than half of participants on the two higher doses lost at least 20% of their starting weight.4PubMed. Tirzepatide Once Weekly for the Treatment of Obesity Those are striking numbers. Before tirzepatide, no approved medication had reliably produced average weight losses exceeding 15% in large trials.
Mazdutide’s data are still building. A phase 3 trial of 4 mg and 6 mg doses in Chinese adults with overweight or obesity showed average weight losses of about 11% and 14%, respectively, over 48 weeks.5PubMed. Once-Weekly Mazdutide in Chinese Adults with Obesity or Overweight The more recent GLORY-2 trial tested a higher 9 mg dose for 60 weeks and found an average loss of roughly 17% of body weight, with about 84% of participants losing at least 5%.6JAMA. Treatment With 9-mg Mazdutide for Weight Reduction in Chinese Adults With Obesity
On the surface, tirzepatide’s top-dose numbers look larger. But there are reasons to be cautious about reading that as a definitive verdict. The mazdutide trials were conducted exclusively in Chinese populations, where baseline body weight and metabolic profiles differ from the predominantly Western populations in SURMOUNT-1. Trial durations also differ: 72 weeks for tirzepatide versus 48 to 60 weeks for mazdutide’s strongest data. Weight loss with these drugs tends to continue deepening out to about 60 to 72 weeks before plateauing, so mazdutide at its shorter time points may not have reached its full effect. A systematic review and meta-analysis pooling data from tirzepatide, mazdutide, and other incretin-based agonists found that, as a class, these multi-receptor drugs reduced body weight by about 11.5% more than placebo, confirming the general potency of the approach without declaring a clear winner between individual agents.7Cardiovascular Research. Comparative analysis of monthly weight-regain dynamics after discontinuation of semaglutide vs tirzepatide
What Kind of Weight Gets Lost
Raw weight loss in kilograms matters, but the composition of that loss matters too. Losing a large proportion of muscle (lean mass) along with fat can weaken bones, reduce metabolic rate, and impair physical function, especially in older adults. Both drugs appear to preserve lean mass reasonably well compared to calorie restriction alone, though neither is perfect on this front.
In the SURMOUNT-1 substudy that measured body composition with imaging, tirzepatide at the maximum tolerated dose produced a roughly 34% reduction in fat mass and an 11% reduction in lean mass over 72 weeks, compared to about 8% and 3% with placebo. That means roughly two-thirds of the weight lost was fat.8PubMed Central. Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study of adults with obesity or overweight Lean mass losses were proportionally smaller than fat losses, but they were not trivial, especially in people who lost 20% or more of their body weight.
Mazdutide’s early body composition data come from a smaller phase 2 trial in Chinese adults. Participants on mazdutide lost more total fat mass than lean mass in absolute terms, and the proportion of body fat relative to total mass decreased in a dose-dependent way. Visceral fat, the deep abdominal fat most strongly linked to metabolic disease, also dropped with increasing doses.9PubMed Central. A phase 2 randomised controlled trial of mazdutide in Chinese overweight adults or adults with obesity These results are encouraging, but the sample was small (only 22 participants had complete imaging data), so the precision of these estimates is limited. Whether mazdutide’s glucagon receptor activation gives it a meaningful edge in preserving lean mass or preferentially targeting visceral fat remains an open question that larger imaging studies will need to answer.
Effects on Blood Sugar and Metabolic Health
Both drugs were originally developed with type 2 diabetes in mind, and their metabolic effects extend well beyond the scale. Tirzepatide has the most extensive evidence here. A large network meta-analysis comparing it with other GLP-1-based therapies found that tirzepatide produced the largest reduction in hemoglobin A1c (a marker of average blood sugar over several months), lowering it by about 2.1 percentage points more than placebo, and also had the greatest effect on fasting blood sugar.10BMJ. Comparative effectiveness of GLP-1 receptor agonists on glycaemic control, body weight, and lipid profile for type 2 diabetes For context, a drop of that size can take someone from poorly controlled diabetes well into the normal range.
Mazdutide has shown strong glucose-lowering effects in its trials as well. In preclinical studies, it improved glucose control through both its GLP-1 and glucagon receptor pathways, maintaining effectiveness even when one of those receptors was experimentally knocked out in mice, suggesting the two pathways work somewhat independently.2PubMed Central. Safety and efficacy of a GLP-1 and glucagon receptor dual agonist mazdutide (IBI362) 9 mg and 10 mg in Chinese adults with overweight or obesity Clinical glycemic data from mazdutide’s phase 3 weight-loss trials have not yet been published with the same depth as tirzepatide’s, so a definitive comparison on blood sugar control is premature.
Liver Fat and Fatty Liver Disease
One of the most medically significant effects of these newer obesity drugs is their impact on fatty liver, now formally called metabolic dysfunction-associated steatotic liver disease. Excess fat in the liver drives inflammation, scarring (fibrosis), and eventually cirrhosis in a subset of patients, and it is now the most common chronic liver condition worldwide. Traditional weight-loss drugs did little for liver fat specifically, but both tirzepatide and mazdutide show promising signals.
Tirzepatide reduces liver fat through multiple routes. In laboratory and animal studies, it decreased liver weight, reduced the accumulation of triglycerides and cholesterol in liver cells, and blunted markers of inflammation and fibrosis.11PubMed Central. Tirzepatide alleviates non-alcoholic fatty liver disease by regulating lipid metabolism through activation of the AMPK/NF-κB signaling pathway Separate research suggests it also reduces the liver’s uptake of fats from the bloodstream by lowering the expression of specific transport proteins.12Genes & Diseases. Tirzepatide, a dual GIP/GLP-1 receptor agonist, alleviates metabolic dysfunction-associated steatotic liver disease by reducing the expression of CD36 and OBP2A In clinical reviews, tirzepatide has shown potential antifibrotic effects, though semaglutide currently holds the strongest evidence for fibrosis improvement and is one of only two drugs specifically approved for this liver condition.13PubMed Central. Pharmacologic Treatment of Metabolic Dysfunction-Associated Steatotic Liver Disease in the Context of Type 2 Diabetes
Mazdutide may have a particular advantage here because of its glucagon receptor activation. Glucagon directly stimulates the liver to oxidize fatty acids and suppresses new fat production, effects that go beyond what GLP-1 alone achieves. Preclinical evidence and early clinical signals suggest that dual GLP-1/glucagon agonists produce marked reductions in liver fat.13PubMed Central. Pharmacologic Treatment of Metabolic Dysfunction-Associated Steatotic Liver Disease in the Context of Type 2 Diabetes Whether mazdutide’s hepatic benefits will prove clinically superior to tirzepatide’s remains to be tested in head-to-head trials, but mechanistically it has a plausible edge.
Side Effects and Tolerability
Both drugs share a similar side-effect profile rooted in their shared GLP-1 receptor activity. Nausea, bloating, early fullness, and mild constipation are the most common complaints, especially during the first weeks and when doses are being increased. These effects stem from the way GLP-1 slows gastric emptying, and they tend to improve over time as the body adjusts.14The Lancet. The expanding role of GLP-1 receptor agonists Gradual dose titration (starting low and increasing over several weeks) is the standard strategy for managing these symptoms, and most participants in the major trials tolerated both drugs well enough to continue treatment.
There are some theoretical reasons to expect differences. Mazdutide’s glucagon component could, in principle, raise blood sugar in some individuals, since glucagon’s primary historical role is to push glucose out of the liver. In practice, the GLP-1 side of the molecule appears to counterbalance that effect, and the clinical trials have not flagged hyperglycemia as a significant concern. The GLORY-2 trial did note that gastrointestinal adverse reactions were more common with mazdutide 9 mg than with placebo, consistent with the general pattern seen across this drug class.6JAMA. Treatment With 9-mg Mazdutide for Weight Reduction in Chinese Adults With Obesity For tirzepatide, the SURMOUNT trials recorded broadly similar GI complaint rates, with nausea and diarrhea being the most common reasons for discontinuation at higher doses.
Severe side effects have been uncommon with both drugs in published trials. Persistent vomiting or severe intolerance usually reflects dose escalation that was too fast, and stepping back to a lower dose typically resolves it. Neither drug has raised major safety red flags in the data published so far, though long-term post-marketing surveillance will be needed for both.
What Happens When You Stop
One of the least-discussed realities of incretin-based weight-loss therapy is what happens after discontinuation. The answer, based on the available evidence, is sobering. A review of randomized studies examining weight trajectories after stopping GLP-1 and GIP/GLP-1 receptor agonists found rapid weight regain regardless of how long the person had been on the drug.15PubMed Central. Weight Regain After Liraglutide, Semaglutide or Tirzepatide Interruption That rebound substantially erodes the metabolic benefits the treatment had provided.
A comparative analysis of post-discontinuation weight dynamics found that roughly two-thirds of the weight lost on either semaglutide or tirzepatide was regained within a year of stopping. The monthly rebound was steeper for tirzepatide, which makes intuitive sense given that tirzepatide produces greater initial weight loss and there is simply more to regain. In relative terms, though, the patterns were similar between the two drugs.7Cardiovascular Research. Comparative analysis of monthly weight-regain dynamics after discontinuation of semaglutide vs tirzepatide No comparable discontinuation data have been published for mazdutide yet, but given its shared GLP-1 mechanism, a similar rebound pattern is widely expected.
This dynamic has major implications for how these drugs are prescribed and perceived. For many patients, effective treatment will mean indefinite use, much like medications for blood pressure or cholesterol. That shifts the conversation toward cost, supply, and long-term tolerability rather than short-term efficacy alone.
Cost and Accessibility
Both drugs are expensive, and their economic profiles are a genuine barrier to widespread use. In the United States, a lifetime cost-effectiveness analysis found that tirzepatide and semaglutide both fell far above the commonly used value threshold. Tirzepatide came in at roughly $197,000 per quality-adjusted life year gained, and semaglutide at about $468,000 per QALY. To reach a $100,000 per QALY threshold typically considered acceptable in U.S. health economics, tirzepatide’s price would need to drop by about 31% and semaglutide’s by about 82%.16JAMA Health Forum. Lifetime Health Effects and Cost-Effectiveness of Tirzepatide and Semaglutide in US Adults
When compared head-to-head against semaglutide rather than against no treatment, tirzepatide looks more favorable. One analysis using data from the SURMOUNT-5 trial estimated that tirzepatide at its maximum tolerated dose was actually less costly and more effective than semaglutide at maximum dose, saving about $42,000 per patient over the modeled time horizon while producing an additional half a quality-adjusted life year. The model also projected fewer cases of type 2 diabetes and cardiovascular disease with tirzepatide.17PubMed. Cost-effectiveness of tirzepatide versus semaglutide for patients with obesity or overweight in the US A separate short-term analysis similarly found tirzepatide cost-effective against semaglutide and liraglutide, with a 98% probability of remaining so at a willingness-to-pay threshold of $150,000 per QALY.18PubMed Central. Tirzepatide vs semaglutide and liraglutide for weight loss in patients with overweight or obesity without diabetes
Mazdutide’s cost picture is less studied but potentially transformative. Developed by Innovent Biologics in partnership with Eli Lilly, it is being positioned primarily for the Chinese and broader Asian markets, where pricing dynamics differ from the U.S. If mazdutide launches at a substantially lower price point than tirzepatide or semaglutide, it could become the first highly effective incretin-based obesity drug accessible to large middle-income populations. No formal cost-effectiveness analyses for mazdutide have been published yet, so this remains speculative.
Quality of Life Beyond the Scale
Weight loss of 15% or more changes daily life in ways that go well beyond metabolic lab values. Tirzepatide’s SURMOUNT trials systematically measured these changes using standardized questionnaires covering physical function, pain, vitality, social activity, and emotional health. The results showed clear, dose-dependent improvements in quality of life scores compared to placebo, and participants who lost 20% or more of their body weight experienced the largest gains. Those with physical limitations at baseline, such as difficulty walking or climbing stairs, saw the most dramatic improvements.19PubMed Central. Association between weight reduction achieved with tirzepatide and quality of life in adults with obesity
The pattern held in people with both obesity and type 2 diabetes. In the SURMOUNT-2 trial, tirzepatide-treated participants reported better physical functioning, less bodily pain, and improved vitality and social functioning relative to placebo at 72 weeks. Again, the improvements were largest in those who lost the most weight and in those who started with the greatest functional limitations.20PubMed Central. Tirzepatide Was Associated with Improved Health-Related Quality of Life in Adults with Obesity or Overweight and Type 2 Diabetes Participants on tirzepatide who had already completed a lifestyle intervention beforehand and then added the drug reported additional quality-of-life gains on top of what diet and exercise alone had achieved.21Diabetes, Obesity and Metabolism. Tirzepatide and health-related quality of life in adults with obesity or overweight
Mazdutide’s trials have not yet reported quality-of-life outcomes in comparable detail. As the drug moves into larger and longer studies, this data gap should narrow. For now, tirzepatide is the only one of the two with published evidence that the weight it removes translates into the kinds of improvements patients actually feel in their daily lives.
The Expanding Pipeline Around Both Drugs
Mazdutide and tirzepatide do not exist in a vacuum. The broader trend in obesity pharmacotherapy is moving toward multi-receptor agonists that combine two or three hormone signals in a single molecule. Retatrutide, a triple agonist targeting GIP, GLP-1, and glucagon receptors simultaneously, has shown marked reductions in liver fat and early signs of even greater weight loss than tirzepatide in preliminary trials.13PubMed Central. Pharmacologic Treatment of Metabolic Dysfunction-Associated Steatotic Liver Disease in the Context of Type 2 Diabetes Orforglipron, an oral GLP-1 agonist, is being developed as a pill-based alternative that avoids injections entirely. CagriSema combines semaglutide with a long-acting amylin analogue. Each of these takes a somewhat different approach to the same underlying insight: that obesity is driven by multiple hormonal pathways, and targeting more than one at a time tends to produce better results.
Where mazdutide fits in this landscape is as a GLP-1/glucagon dual agonist occupying distinct mechanistic territory from tirzepatide’s GIP/GLP-1 combination. The two drugs are not competitors in the way that two GLP-1-only drugs would be. They test fundamentally different hypotheses about which receptor combinations matter most. If both prove safe and effective at scale, the field may eventually stratify patients based on metabolic phenotype: people with prominent liver fat might benefit more from glucagon receptor activation (favoring mazdutide), while those with insulin resistance or high fasting glucose might respond better to GIP/GLP-1 co-agonism (favoring tirzepatide). That kind of precision prescribing is years away from clinical reality, but the mechanistic groundwork is already being laid.