A new study has found that adopting a Mediterranean-style diet can help with weight loss and improve diet quality but offers no clear cognitive benefits in older adults with obesity.
The findings, published in Preventive Medicine Reports, come from the Building Research in Diet and Cognition (BRIDGE) trial led by researchers in Chicago.
The randomised controlled trial involved 185 adults aged 55 to 85, 91% of whom identified as African American. All participants had obesity (BMI 30–50) and low baseline adherence to the Mediterranean Diet, which emphasises fruits, vegetables, whole grains, olive oil, and fish.
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The study addressed the lack of high-quality dietary research in African American populations, who face higher rates of dementia and obesity.
Participants were assigned to one of three groups: Mediterranean diet with calorie-restricted weight loss (MedWL), Mediterranean diet without weight loss (MedA), or a control group maintaining their usual diet.
Both intervention groups attended weekly classes for eight months, received extra-virgin olive oil and almonds, and were encouraged to adopt Mediterranean eating patterns.
The MedWL group also aimed for 5–7% weight loss through reduced calorie intake and increased physical activity.
After the eight-month active phase and a six-month maintenance period, both intervention groups showed significant improvements in diet quality compared to controls.
MedWL participants lost an average of 3.8 kg, significantly more than the modest 1.7 kg in the MedA group or 0.5 kg in controls. The MedWL group also saw greater reductions in BMI and harmful visceral fat.
However, despite these physical health gains, the study found no measurable improvements in memory, executive function, or information processing in any group over the 14-month period.
While all groups displayed slight cognitive improvements, likely due to practice effects from repeated testing, no meaningful differences emerged between them.
Secondary measures, including blood pressure, insulin resistance, blood sugar, and cholesterol, showed no significant between-group differences.
Physical activity increased during the active phase but returned to near-baseline levels during maintenance.
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Importantly, adherence to the Mediterranean diet remained higher than baseline across both intervention groups, though slightly reduced after the intensive phase. Weight regain in the MedWL group was minimal.
The study’s authors conclude that while the Mediterranean diet, particularly when combined with weight loss, can safely improve cardiometabolic health, its impact on cognitive function may require longer or more intensive interventions.
They highlight the importance of culturally tailored dietary programmes for diverse communities and call for further research to explore long-term brain health outcomes.
