The recently published SURMOUNT trial established the efficacy of tirzepatide. In this phase 3, controlled study, 2,539 people were randomized to receive either tirzepatide (at 5, 10 or 15 mg) or a placebo. After 72 weeks of treatment, the following results were observed:

• With the placebo, the average weight loss was 3.1 percent.
• With 5 mg tirzepatide, the average weight loss was 15 percent.
• With 10 mg tirzepatide, weight loss increased to 19 percent.
• At 15 mg, the average weight loss was a remarkable 20.9 percent. (Wegovy, the previous weight loss leader, has an average weight loss of 15 percent.)