This article originally appeared on Medical News Today
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According to a new study, a once-weekly dose of tirzepatide can lead to significant, sustained weight loss for up to 3 years in adults with overweight or obesity who do not have diabetes.
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The findings build on earlier results from the SURMOUNT-1 trial and suggest that treatment responses may vary based on factors such as sex and the presence of obesity-related conditions.
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Researchers also identified patterns in how participants lost weight over time.
A new study, presented at this year’s European Congress on Obesity (ECO) in Malaga, Spain (11–14 May) found that a once-weekly dose of tirzepatide can lead to significant and consistent weight loss for up to 3 years in adults with overweight or obesity who do not have diabetes.
The study also suggests that women and individuals without obesity-related health issues may respond more effectively to tirzepatide (Mounjaro) therapy.
Researchers from the University of Padova in Italy, in collaboration with Eli Lilly and Company, have extended findings from the SURMOUNT-1 phase 3 trial of tirzepatide. This secondary analysis is yet to appear in a peer-reviewed journal.
The medication works by imitating the actions of two gut hormones which are released after eating and help stimulate insulin production: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).
It also aids weight management by decreasing appetite, achieved through delaying stomach emptying and activating brain regions with GLP-1 receptors that signal satiety.
In 2022, the SURMOUNT-1 trial showed that adults taking tirzepatide for 72 weeks lost, on average, between 15% and 21% of their starting body weight, depending on the dose.
Updated analysis shows lasting weight loss on tirzepatide
This updated analysis looks more closely at 700 of those participants (most of whom were women), with an average age of 48, who consistently took their medication (receiving at least 75% of their doses).
All participants in this group were either living with obesity (a body mass index, or BMI, over 30) or were overweight (BMI of 27 or higher) and had prediabetes.
The researchers analysed the average percentage of body weight lost from the start of the trial to week 176 (three years) and also measured how long it took participants to achieve a 20% reduction in weight.
Based on this information, they divided participants into three groups.
They then looked at how each group’s starting characteristics related to their weight loss patterns and whether they reached a plateau.
A weight loss plateau was defined as a period with less than a 5% change in body weight over three months following the initial weight loss, and during all later three-month periods.
The groups were similar in terms of average age, how long they had been living with obesity, whether they smoked and their starting BMI.
Analysis reveals 3 distinct weight loss patterns
Group 1 (248 people) showed a steady rate of weight loss, averaging about a 10% reduction, and reached a plateau earlier in the study.
Group 2 (226 people) lost weight more quickly at the start (around 20% of their body weight) before hitting a plateau later on.
Group 3 (also 226 people) saw the most rapid and substantial weight loss, averaging around 30%, and took the longest time to reach a plateau.
Researchers explained that those in the first group maintained an average weight loss of nearly 10% from their starting body weight after 3 years.
In contrast, the third group, characterised by a higher proportion of females and individuals without obesity-related health conditions, achieved an additional 20% reduction. This resulted in an overall average weight loss of approximately 31%.
Researchers found clear differences in how long it took each group to reach a weight loss plateau by the end of the three-year treatment.
Most participants in Groups 1 and 2 (about 88%) had hit a plateau by the end of the study, compared to just over 81% in Group 3.
Among those who did reach a plateau, the timing varied.
The majority in Groups 1 and 2 stopped losing weight at around 24 weeks into treatment. In Group 1, about three-quarters had plateaued by this point, and in Group 2, nearly half had.
In contrast, most of those in Group 3 took longer to reach a plateau, with over 80% of them doing so between weeks 36 and 48, showing a more extended period of weight loss before levelling off.
Weight loss plateaus are normal, but benefits remain
Researchers explained that hitting a weight loss plateau is a natural part of any weight management approach, as the body eventually activates mechanisms to prevent further weight loss.
This is due to the complex interplay of multiple hormones that regulate appetite and body weight and GLP-1 and GIP are only two among several involved in this process.
Despite identifying three distinct patterns in weight loss over time, researchers noted that the majority of participants were able to maintain clinically significant weight reduction over the three-year period, regardless of factors such as age, how long they had been living with obesity, or their starting BMI.
They emphasized that even modest weight loss, around 5% of initial body weight, can significantly reduce the risk of developing diabetes and improve heart health by lowering blood pressure and cholesterol.
Greater weight loss, around 15%, is linked with the most substantial health improvements.
The findings, according to researchers, could help improve understanding of how tirzepatide works across different patient groups and support more personalised treatment strategies and goals.
The trial did not reveal any new safety concerns, with the most frequently reported side effects being nausea, diarrhoea and constipation.
Three experts, not involved in this research, spoke to Medical News Today.
Mir Ali, MD, a board-certified general surgeon, bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, said that he “thought this was a good study showing that these medications are very effective for substantial weight loss.”
“Also, it showed that individuals respond differently and there can be periods of weight loss plateaus. We also see weight loss plateaus in surgical weight loss patients,” Ali added.
However, he noted that “patients need to be counseled thoroughly on expectations and results.”
“Each person responds differently, and it is important to continue these medications long term. There is a tendency for patients to get discouraged when they encounter weight loss plateaus.”
– Mir Ali, MD
Jordan Hill, MCD, RD, CSSD at Live it Up, pointed out that “the SURMOUNT-1 3-year study is among the first longitudinal study to highlight the effect of tirzepatide treatment on long-term weight loss in people with prediabetes.”
“Based on the results, it presents as a promising treatment solution for meaningful weight loss that is sustained over years at a time,” Hill added.
“While people responded to the treatment differently, there appears to be meaningful weight loss regardless of pace. Further research is warranted to understand any confounding factors that lead to the differences in pace of weight loss as well as what maintenance of the weight loss may look like if subjects discontinue treatment.”
– Jordan Hill, MCD, RD, CSSD
Ongoing support and education needed to achieve benefits
Destini Moody, RD, CSSD, LD, a registered dietitian specializing in sports performance, body composition changes and injury recovery, highlighted the importance of proper education.
Moody suggested that: “People [with] overweight and obesity got where they are likely due to a lack of nutritional knowledge. Thus, these medications will do little for long term health when patients come off the medication of a prescription is not accompanied with proper education.”
In summary, Hill noted that “this research supports the idea of medical intervention and therapeutic approaches to managing weight in those with prediabetes.”
“It reinforces that meaningful, sustained weight loss may be possible with the right treatment and creates opportunities for more personalized weight loss and care strategies,” Hill concluded.
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