Retatrutide Fat-Jab Study Shows Significant Weight Loss, Outperforming Mounjaro

An experimental weight-loss drug, codenamed 'Godzilla' and known as Retatrutide, has demonstrated the potential to help obese patients with type 2 diabetes lose up to a quarter of their body weight, according to new research. The drug, which targets three hormone pathways involved in appetite control, also showed improvements in blood pressure and cholesterol levels, potentially rivaling current leading treatments like Mounjaro.

Results from the phase 3 TRIUMPH-2 clinical trial, involving 1,152 overweight and obese adults with type 2 diabetes, were presented at the Annual Meeting of The European Association for the Study of Diabetes (EASD) in Milan. Participants received weekly injections of Retatrutide at doses of 4mg, 9mg, or 12mg, or a placebo, in conjunction with diet and exercise advice. After 80 weeks, those on the highest 12mg dose lost nearly a fifth of their body weight on average. Nearly half of participants on this dose lost at least 20% of their body weight, and almost a third shed at least 25%.

In comparison, the most potent currently approved weight-loss drug, Mounjaro, helps users lose approximately 20.9% of their body weight over 16.5 months. In the Retatrutide trial, participants taking a placebo lost only 5% of their weight through diet and exercise alone.

Retatrutide, also referred to as 'triple G,' is a triple agonist, meaning it activates three hormone pathways: GLP-1, GIP, and glucagon. This multifaceted approach is believed to aid the body in burning fat more effectively than drugs targeting fewer pathways. For instance, Wegovy targets one pathway (GLP-1), while Mounjaro targets two (GLP-1 and GIP).

Beyond weight loss, Retatrutide significantly improved blood sugar control. Nearly 75% of patients on the highest dose achieved blood sugar levels at or below the diagnostic threshold for diabetes, compared to 29% in the placebo group. Participants also showed marked improvements in other cardiovascular risk factors, including reductions in 'bad' cholesterol and inflammation.

However, like other GLP-1-based medications, Retatrutide was associated with side effects. Nausea and diarrhea were reported, and seven percent of participants on the highest dose experienced abnormal skin sensations like burning and discomfort. Seven deaths occurred during the study, but investigators deemed them unrelated to the treatment.

Researchers concluded that Retatrutide could significantly advance the treatment of obesity and type 2 diabetes, particularly for individuals for whom weight reduction has been challenging. The drug's safety profile appears similar to other weight-loss injectables. Further research is planned to assess its impact on obesity-related conditions such as sleep apnea, stroke, and heart disease.

Eli Lilly, the pharmaceutical company developing Retatrutide, has issued warnings against obtaining the drug through unauthorized social media channels, citing serious health risks. Reports of suspected side effects linked to Retatrutide have been recorded by the UK's Medicines and Healthcare products Regulatory Agency (MHRA) since 2025.

While Retatrutide is not yet approved or available on the NHS, experts suggest it could be accessible within three years if regulatory approval is granted. In parallel, separate research presented at EASD highlighted an experimental drug called petrelintide, which mimics the hormone amylin to promote a longer-lasting feeling of fullness, potentially offering similar weight loss to Mounjaro with fewer gastrointestinal side effects.