What happens to patients in the Surmount trial when switched to a placebo, comparing outcomes at week 88 to week 36?

Weight Regain After Switching from Tirzepatide to Placebo in the SURMOUNT Trial

In the SURMOUNT trial, patients who were switched from tirzepatide to placebo at week 36 experienced significant weight regain by week 88, losing approximately half of the weight loss benefits they had achieved during active treatment.

Weight Outcomes After Switching to Placebo

• When patients in the SURMOUNT trial were switched from active tirzepatide treatment to placebo at week 36, they experienced substantial weight regain by week 88 1
• The placebo effect initially seen during active treatment diminished over time after switching to placebo, with weight regain becoming evident as the trial progressed 1
• This pattern of weight regain after discontinuation of active therapy aligns with what has been observed in other clinical trials where patients are switched from active treatment to placebo 1

Magnitude of Weight Regain

• By week 88 (approximately one year after switching to placebo), patients had regained approximately half of the weight they had lost during the active treatment phase 1
• This weight regain pattern demonstrates that the metabolic benefits of tirzepatide are dependent on continued treatment, similar to what has been observed with other anti-obesity medications 1
• The weight regain phenomenon follows a predictable pattern where benefits gradually diminish after discontinuation of the active medication 1

Comparison to Continued Treatment

• Patients who remained on tirzepatide throughout the entire study period maintained their weight loss, in stark contrast to those switched to placebo 1
• This difference highlights the importance of continued therapy for maintaining the metabolic benefits achieved with tirzepatide 1
• The divergence in outcomes between those continuing active treatment versus those switched to placebo became increasingly pronounced over time between weeks 36 and 88 1

Clinical Implications

• The significant weight regain observed after switching to placebo suggests that tirzepatide therapy needs to be continued long-term to maintain weight loss benefits 1
• This pattern is consistent with the understanding that obesity is a chronic disease requiring ongoing management rather than a condition that can be "cured" with short-term intervention 1
• The weight regain observed in the SURMOUNT trial is similar to what has been observed in other weight loss medication trials when active treatment is discontinued 1

Physiological Mechanisms

• The weight regain likely reflects the reversal of tirzepatide's effects on appetite regulation, energy expenditure, and metabolic processes once the medication is discontinued 1
• This pattern demonstrates that the biological drivers of obesity return when pharmacological intervention is removed 1
• The gradual nature of the weight regain (occurring over approximately 52 weeks after switching to placebo) suggests a complex physiological adaptation rather than an immediate rebound effect 1