Intermittent fasting boosts memory and attention in obese people

Beyond being an effective weight-loss strategy, alternate-day intermittent fasting (ADA) could become a key tool for protecting brain health. This is demonstrated by a study led by researchers from the Biomedical Research Institute of Malaga (IBIMA BIONAND Platform).

The research, published in ' Gut ', shows that a dietary pattern that alternates days of normal eating with days of severe calorie restriction not only reduces body fat, but also significantly improves cognitive functions such as memory, sustained attention, and inhibitory control in people with obesity.

Obesity is one of the world's leading public health concerns. In addition to its known association with diseases such as type 2 diabetes and hypertension, several studies have shown its impact on brain function, including earlier cognitive decline.

Until now, many dietary strategies have focused on weight management, but few have simultaneously addressed metabolic and neurological effects. This new study provides solid evidence of how a specific dietary pattern can target the gut-brain axis to achieve both goals.

The three-month clinical trial included 96 obese adults , randomly divided into three groups: one on a low-calorie Mediterranean diet, another on a ketogenic diet, and a third on intermittent fasting on alternate days.

All participants were evaluated using neuropsychological tests before and after the intervention, and blood inflammatory markers and the composition of their gut microbiota were also analyzed. In the ADA group, in vitro studies were also conducted with microglial cells derived from their blood, as well as transplants of their microbiota into animal models.

Although all three groups achieved similar weight loss (around 7%), the greatest cognitive benefits were seen in the intermittent fasting group. This group showed greater improvement on tests of working memory, processing speed, and executive control.

In parallel, a significant reduction in proinflammatory markers such as ferritin and MCP-1 was detected, as well as a profound remodeling of the intestinal microbiota: microorganisms that produce beneficial fatty acids such as butyrate increased, and those associated with chronic inflammation and neurotoxicity decreased.

Furthermore, experiments in mice confirmed that the microbiota of participants who performed ADA improved brain immune function, activating "cleaning" microglia and reducing obesity-associated neuroinflammation.

"These findings change the paradigm: it's not just what we eat that matters, but when we eat it. Two diets can achieve the same weight loss, but with very different effects on the brain," highlights Francisco J. Tinahones , co-leader of the research.

" ADA generates chemical signals from the gut that act directly on the brain's immune system ," adds Virginia Mela, co-lead author of the study. "And it does so in an accessible way, without supplements, drugs, or exotic foods," concludes Isabel Moreno-Indias, who is also the study's leader.

This study lays the groundwork for future clinical research focused on populations at high risk for cognitive decline, such as people with prediabetes, metabolic syndrome, or older adults. The IBIMA BIONAND Platform team is already working on developing precision nutrition programs for the brain, integrating the ADA with personalized recommendations based on each individual's microbiota.

In addition to its therapeutic applications, researchers suggest that alternate-day intermittent fasting could be incorporated, always under medical supervision , as a strategy to improve daily cognitive performance.