In a groundbreaking study presented at the 2023 annual meeting of The Obesity Society, drugmaker Eli Lilly revealed that their appetite inhibiting drug, Tirzepatide, marketed as Mounjaro, led to a remarkable 26% reduction in body weight among participants who underwent intensive lifestyle interventions. The findings of this research were published in the journal Nature Medicine.
The study, led by Dr. Thomas Wadden, a professor of psychology in psychiatry at the University of Pennsylvania’s Perelman School of Medicine, featured a group of individuals with obesity. Prior to receiving Tirzepatide, these participants had already achieved a 6.9% reduction in their baseline body weight through traditional diet and activity counseling over a 12-week period. Following the introduction of Tirzepatide, they went on to lose an additional 18.4% of their body weight, in stark contrast to a 2.5% weight gain observed in the placebo group. This additional weight loss also led to significant health improvements, including reduced waist circumference, improved blood pressure, cholesterol, triglycerides, blood sugar levels, and enhanced physical functioning.
The impressive weight loss results were achieved over a 72-week period, with a further slight decrease recorded during an additional 12-week period, ultimately totaling a 26% reduction over 84 weeks.
Tirzepatide, sold under the brand name Mounjaro, is primarily FDA-approved for the treatment of type 2 diabetes. However, previous studies have suggested its efficacy for weight loss as well, leading to off-label prescriptions for obesity treatment. Dr. Aleem Kanji, an endocrinologist with Ethos Endocrinology, stated that the FDA’s approval for obesity treatment could enhance access for those in need of such therapy.
Dr. Kristen Williams, the medical director of the weight-loss program MyJourneyMD, emphasized that while Tirzepatide isn’t a traditional diet drug, the results from this study are particularly exciting for the treatment of obesity. Previous FDA-approved drugs for obesity typically aimed for a 10% body weight reduction, making the results achieved with Tirzepatide—exceeding 25%—quite remarkable and possibly addressing the metabolic aspect of obesity.
The success of this treatment hinged on the combination of the drug with a comprehensive lifestyle intervention, as detailed in the SURMOUNT-3 study. This multi-center, randomized, double-blind, placebo-controlled trial involved participants with obesity and those who were overweight with weight-related co-morbidities. Regular counseling sessions with registered dietitians played a vital role in helping participants maintain a balanced diet with a calorie deficit and regular exercise, in addition to receiving the drug.
Nonetheless, the study also underscores the importance of considering side effects and long-term sustainability. Common side effects of Tirzepatide include nausea, vomiting, face swelling, stomach pain, diarrhea, and constipation. Questions regarding weight maintenance after discontinuing the drug and whether the reported weight loss includes muscle mass rather than fat are yet to be answered.
Tirzepatide, administered weekly, activates receptors for the hormones GIP and GLP-1, located in areas of the brain involved in appetite regulation. This mechanism decreases food intake by increasing feelings of fullness and reducing hunger and reward-based eating. Dr. Mir Ali, a bariatric surgeon and medical director, emphasized the importance of surgical intervention for eligible patients, while acknowledging the potential benefits of Tirzepatide for diabetic individuals who do not meet surgical criteria. It appears that this drug represents a significant advancement in the ongoing effort to combat obesity and its related health issues, though further research is required to establish long-term safety and efficacy, as well as its impact on cardiovascular outcomes and mortality. It is crucial to recognize that, despite these promising results, a holistic approach that includes diet, exercise, and professional guidance remains essential in the journey towards effective weight loss.