What this means
Researchers randomly assigned older adults with obesity to lifestyle changes, with or without metformin, or diet education with metformin. Adding metformin to intensive lifestyle changes did not improve physical function beyond lifestyle changes alone.
Plain-English summary written by an AI model from the abstract. The original is below.
- Who it was tested in
- 114 older adults with obesity
- Kind of research
- A clinical trial in people
The science
- Original title
- Metformin added to lifestyle intervention for physical function in older adults with obesity (DEMFOS trial): a randomised controlled trial.
- Authors
- Nava MLD, Viola V, Aguilar M et al.
- Journal
- The lancet. Healthy longevity
- Published
- Jul 30, 2026
- Study type
- Clinical trial · in humans
- PMID
- 42532077 ↗
Abstract
Background
Obesity in older adults is associated with functional decline and increased risk of disability. Lifestyle interventions improve physical function, but the role of metformin as an adjunct to lifestyle intervention in this population remains unclear. In this randomised clinical trial, we evaluated whether metformin enhances the effects of an intensive lifestyle intervention on physical function in older adults with obesity.
What they did
The Diet and Exercise plus Metformin to Treat Frailty in Obese Seniors (DEMFOS) trial (ClinicalTrials.gov: NCT04221750 [completed]) was a randomised, placebo-controlled trial conducted at the Michael E DeBakey Veterans Affairs Medical Center and Baylor College of Medicine (Houston, TX, USA). Older adults (aged 65-85 years) with obesity (BMI ≥30 kg/m2) were randomly assigned to intensive lifestyle intervention (weight-management and exercise training) plus placebo, intensive lifestyle intervention plus metformin, or healthy lifestyle (diet education) plus metformin groups. The primary outcome was change in the modified physical performance test score at 6 months. The primary analysis was by intention-to-treat.
What they found
Of 221 participants assessed for eligibility between March 30, 2021, and Dec 12, 2024, 114 were included in this study (mean age 72·8 years [SD 5·2]; 101 [89%] men and 13 [11%] women). 64 (56%) participants were White, 50 (44%) were Black, and 15 (13%) were Hispanic or Latino. Changes in physical performance test differed between groups (group-by-time interaction p<0·0001). At 6 months, physical performance test improvement was greater in the intensive lifestyle plus metformin group than in the healthy lifestyle plus metformin group (mean difference 2·5 points, 95% CI 1·2-3·8; p=0·0002), whereas there was no difference between the intensive lifestyle plus metformin and intensive lifestyle plus placebo groups (0·1 points, -1·2 to 1·4; p=0·92). Serious adverse events were infrequent and not attributed to the study interventions. Our findings suggest that in older adults with obesity undergoing intensive lifestyle intervention, metformin does not provide additional improvement in physical function. These results support prioritising lifestyle-based strategies to improve functional outcomes in this population.
Other details
US Department of Veterans Affairs.
The authors' abstract, grouped under plain headings from its own section labels.
Nava MLD, Viola V, Aguilar M et al. Metformin added to lifestyle intervention for physical function in older adults with obesity (DEMFOS trial): a randomised controlled trial. The lancet. Healthy longevity. 2026. doi:10.1016/j.lanhl.2026.100883. PMID: 42532077. https://pubmed.ncbi.nlm.nih.gov/42532077/
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