A recent review has indicated that the weight-loss drug retatrutide, referred to as ‘Godzilla’, may surpass Mounjaro, which is currently the most potent injection available.
Retatrutide is an experimental treatment being developed by Eli Lilly and Company, the same creators of Mounjaro.
This medication functions by targeting three distinct hormone receptors, leading to a significant reduction in appetite and an increase in fat burning, whereas existing drugs like Wegovy and Mounjaro focus on only one or two receptors.
In a prior study involving over 2,300 adults with excess weight, participants who received the highest dosage experienced an average weight loss of 28.3 percent, with some individuals shedding approximately 5 stone.
“It was remarkable to observe that every dosage of retatrutide led to clinically significant weight loss for nearly all participants, and individuals suffering from severe obesity on the highest dosage lost, on average, 30 percent of their body weight over a two-year period,” stated Professor Ania Jastreboff, the principal investigator of the trial at Yale School of Medicine.
Retatrutide is dubbed the ‘Godzilla’ jab because it is a powerful triple-hormone receptor (Getty Stock Images)
Retatrutide > Mounjaro?
The recent review, entitled ‘Efficacy and Safety of Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss Among Adults Without Diabetes’, has determined that Mounjaro ranks among the most effective weight-loss medications, resulting in approximately 19 percent greater weight loss than
placebo
after about 72 weeks.
Retatrutide, however, showed even greater results, at around 22 percent after 48 weeks.
A new review has suggested that ‘Godzilla’ weight-loss drug tirzepatide may outperform Mounjaro (Getty Stock Images)
Semaglutide treatments produced around 14–15 percent more weight loss than placebo, while orforglipron produced around 12 percent.
But because the studies were designed differently, the drugs cannot be directly compared.
The updated study, published in August 2026, reviewed 38 clinical trials involving 25,816 people who were overweight or
obese
but did not have diabetes.
Researchers analyzed 17 GLP-1-based medications, utilizing trials published until March 2026, and assessed their weight-loss outcomes and side effects over follow-up durations of up to two years.
“Researchers affiliated with Jewish General Hospital and McGill University performed an update to their previous systematic review regarding the safety and effectiveness of GLP-1 receptor agonists for weight loss in adults without diabetes, in order to incorporate newly introduced agents and the growing body of evidence surrounding these therapies,” stated the American College of Physicians (ACP).
(Getty Stock Images)
In the various studies, participants who were administered GLP-1 receptor agonists (RAs) experienced a significantly greater weight loss compared to those who received a placebo, with certain new treatments resulting in weight reductions exceeding 20 percent of total body weight.
Although gastrointestinal side effects were commonly reported, instances of serious adverse events and fatalities were infrequent, and no new safety issues were noted.
Limitations of the study
The 38 trials varied in their design, dosages of the drugs, duration of treatment, and characteristics of the participants, which prevented researchers from conducting a formal meta-analysis or directly comparing the drugs against one another.
Additionally, the follow-up period was restricted to a maximum of approximately two years, which means the review is unable to determine the long-term effectiveness or safety of the treatments.
Furthermore, the trials did not specifically evaluate sarcopenia, which refers to the loss of muscle mass and strength. This is significant because some of the weight lost with GLP-1 medications may consist of lean mass rather than fat.
Featured Image Credit: Peter Dazeley via Getty Images