In a just released study showing the result of a clinical trial of participants with obesity, tirzepatide—a promising new drug—provided substantial and sustained reductions in body weight. This is important for longevity because obesity is the number-one cause of preventable shortened life expectancy due to a higher incidence of diabetes, cancer, cardiovascular disease, and kidney disease. Over 40% of Americans are currently categorized as obese.

In this phase 3 double-blind, randomized, controlled trial, they assigned 2539 adults with a body-mass index (BMI) of 30 or more, or 27 or more and at least one weight-related complication, excluding diabetes, to receive once-weekly, subcutaneous tirzepatide (5 mg, 10 mg, or 15 mg) or placebo for 72 weeks

At baseline, the mean body weight was 230 pounds, the mean BMI was 38.0, and 94.5% of participants had a BMI of 30 or higher. The average percentage change in weight at week 72 was down 15.0% with 5-mg weekly doses of tirzepatide, down 19.5% with 10-mg doses, and down 20.9% with 15-mg doses versus down only 3.1% with the placebo. It is remarkable that the magnitude of weight loss with tirzepatide was similar to that with gastric bypass, which raises the potential for alternative medical approaches to the treatment of obesity.

The percentage of participants who had weight reduction of 5% or more was 85%-91% with tirzepatide, compared to just 35% with the placebo. 50% and 57% of participants in the 10-mg and 15-mg groups had a reduction in body weight of 20% or more—which would be over 45 pounds of weight loss in under a year and a half—as compared with only 3% in the placebo group. Improvements in all cardiometabolic measures were observed with tirzepatide. Treatment also reduced waist circumference and lowered blood pressure, lipids, and fasting insulin. The most common adverse events with tirzepatide were gastrointestinal—such as nausea, diarrhea, and constipation—and most were mild to moderate in severity. Adverse events caused treatment discontinuation in only 4%-7% of participants.

This drug, if and when approved by the FDA, could be a major game changer. In the past, we have seen promising weight-loss drugs develop harmful and unexpected side effects. But, if proven safe, this could be life changing for millions of people.