Walnuts had little effect on body fat and weight in older adults
In a two-year randomized controlled trial of 326 healthy older adults, daily walnuts had little effect on body composition compared with avoiding walnuts.
Our read
Interventions- Studied:
- Randomized trial in 326 healthy older adults, against adults following usual diets without walnuts (Blinded, sample size calculated, registered NCT01634841)
- What changed:
- Body weight and body fat did not differ between older adults eating walnuts and those avoiding walnuts
- The catch:
- The California Walnut Commission sponsored the trial and supplied the walnuts
- In the record:
- The 9th paper on walnuts with results in people; 16 on record in all.
Editor of record: Boris Djordjevic · AgingResearch.News
The analysis included 326 healthy adults aged 63–79, including 220 women, in Barcelona, Spain, who completed a two-year randomized controlled trial. Participants added 30–60 grams of walnuts daily to their usual diet, or avoided walnuts. The walnut group received no advice to replace other foods or restrict calories. Scans measured body fat and fat-free tissue before and after the intervention.
Walnuts had little effect on body composition compared with the control diet, including no differences in weight, total fat or fat-free tissue. Women eating walnuts had a small increase in the ratio of abdominal to hip-and-thigh fat percentages. An exploratory analysis found adverse body composition changes in men with one version of FTO, an obesity-linked gene, compared with men carrying another version on the walnut diet. That subgroup was small.
Why it matters
For older adults, the trial addressed whether adding fat-rich walnuts to the usual diet contributes to the body fat changes that accompany aging.
Caveats
The authors note that this analysis covered only healthy older adults at the Barcelona site; results might differ in younger people or with other regional diets.
Where the evidence stands
Walnuts
- 6 independent labs in 4 countries
- 7 trials
- Funders: California Walnut Commission and others
- 3 of 17 findings with company ties
From the paper
- Participants
As pre-specified in the design of the WAHA trial [15], changes in body weight and BMI were the primary outcome, and changes in body composition by DXA were a secondary outcome at the Barcelona node, where 352 subjects were randomized.
- Limitation
This was a secondary, pre-specified outcome limited to the Barcelona node of the WAHA trial, involving healthy elderly participants.
Quoted word for word from the full text on mdpi.com.
The paper
Hospital Clínic de Barcelona; Instituto de Salud Carlos III (ISCIII)
Nutrients, Nov 13, 2026, Open access, CC BY
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