The study, published in Obesity, was selected for the Obesity Journal Symposium at ObesityWeek 2026.

NATIONAL HARBOR, Md., Nov. 14, 2026 /PRNewswire-PRWeb/ -- Adults in Key to Health's metabolic health program lost an average of 9.6% of their body weight over two years without medication, according to a study of 11,365 people published today in Obesity, the journal of The Obesity Society.

The weight loss held through the second year, when regain typically sets in. An earlier 155-person randomized controlled trial of the program found 9.5% weight loss at 48 weeks, compared with 2.6% for the WW app. The new real-world study shows similar results in a population more than 70 times larger. In the study, participants used the program's breath sensor and companion app on their own. The app provided the guidance, with no medication, human coaching, or physician oversight, which other programs with similar results have typically included.

Most published results from digital weight-loss programs end at one year or sooner. To the authors' knowledge, this is the largest published study of a non-drug digital weight-loss program to report percentage weight loss at two years.

The paper was selected by the journal's editors for the 14th Annual Obesity Journal Symposium, which showcases top research published in Obesity. First author Ray H. Wu, MD, MBA, Key to Health's founder and CEO, presents the findings Sunday at ObesityWeek 2026. Co-authors are from Miguel Servet University Hospital in Spain, the University of British Columbia's Okanagan campus and Pennington Biomedical Research Center at Louisiana State University.

How it works

Key to Health replaces calorie counting with real-time feedback. Members use a noninvasive, handheld breath sensor that measures acetone, a natural byproduct of the body burning fat for energy. A quick breath test shows whether their body is burning fat, so they can see how their choices affect them and adjust day by day. Rather than a restrictive diet, the app guides a Mediterranean-style approach with fewer ultra-processed foods, in line with USDA dietary guidelines, that members adapt to their own lifestyle.

Key findings

• Nearly 10% at two years. Average weight loss was 9.6% at two years (95% CI, 8.8%–10.4%), up from 9.3% at one year.
• Clinically meaningful for most. Of participants weighed at two years, 77% had kept off at least 5% of their body weight and 45% at least 10%.
• More use, more loss. Participants who used the breath sensor most often in their first 12 weeks lost 10.8% at two years, compared with 7.4% for the least frequent users.
• Broad results. Every age, sex and starting-weight group lost more than 5% at two years. Participants 65 and older lost the most (11.3%), and women lost more than men (10.5% vs. 9.0%).
• Robust to dropout. Results were nearly identical in prespecified analyses designed to account for participants who stopped logging their weight (9.5%), and consistent across five enrollment years, 2018 to 2023.

"To lose weight and keep it off, you have to make lasting changes that fit your lifestyle," said Dr. Wu. "Key to Health gives people real-time feedback on how their bodies respond to the food and exercise they enjoy. When you can see what's working, new habits form naturally."

"Long-term results have been the missing piece for digital weight-loss programs," said Dr. Jonathan Little, professor in the School of Health and Exercise Sciences and Principal's Research Chair in Metabolism at the University of British Columbia's Okanagan campus, and the study's senior author. "Seeing the results of our randomized trial essentially reproduced in more than 11,000 people in everyday use, and sustained for two years, is a meaningful addition to the evidence."

Presentation: Sunday, Nov. 15, 6:20 p.m. ET, 14th Annual Obesity Journal Symposium, ObesityWeek 2026, Gaylord National Resort & Convention Center, National Harbor, Md., Potomac D456.

Publication: Wu R, Rodrigo Carbó C, Falkenhain K, Little JP. Two-Year Weight Loss With a Breath Biofeedback mHealth Program: A Real-World Evidence Study. Obesity. 2026. https://doi.org/10.1002/oby.70309. Analysis plan registered in advance (ClinicalTrials.gov NCT07430618).

Randomized trial: Falkenhain K, et al. Obesity. 2021;29(10):1606–1614. One-year follow-up: Falkenhain K, et al. Obesity Science & Practice. 2025;11(6):e70106.

Funding and disclosures: Keyto, Inc. (dba Key to Health) sponsored the study. Dr. Wu is Key to Health's CEO and a shareholder. Ms. Rodrigo Carbó received consulting fees from Key to Health. Drs. Falkenhain and Little received no compensation for this work. Full disclosures appear in the paper.

About Key to Health

Key to Health (Keyto, Inc.) is a metabolic health program that helps people lose weight and keep it off, combining app-guided nutrition with a handheld breath sensor. It is supported by a randomized controlled trial and two years of real-world results. Key to Health works with employers and health plans to support members, including people using GLP-1 medications. The company is based in San Francisco. https://www.keytohealth.ai

Media Contact

Key to Health Media Team, Keyto, Inc. (dba Key to Health), 1 415-323-3686, hello@keytohealth.ai, https://www.keytohealth.ai

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SOURCE Keyto, Inc. (dba Key to Health)