A new study by researchers from Oxford University, University College London, and several institutions in Germany, France, and the Netherlands has found that diet quality and body fat distribution during midlife can influence brain health and cognitive function later in life.
The study, published in JAMA Network Open, examined data from the Whitehall II Study, a long-term research project following British civil service workers since 1985.
As global diets have changed, obesity, heart disease, and diabetes have become more common. These health problems also increase the risk of dementia.
Most past research has focused on how specific nutrients affect brain function, but fewer studies have looked at overall diet quality and body fat distribution over many years.
This study aimed to fill that gap by analyzing how midlife diet and waist-to-hip ratio (a measure of body fat distribution) relate to brain connectivity and memory in old age.
The researchers studied 512 participants for diet quality and 664 participants for waist-to-hip ratio. These individuals, part of the Whitehall II Imaging Study, underwent brain scans and cognitive tests between 2012 and 2016, at an average age of 70.
To measure diet quality, researchers used the Alternative Healthy Eating Index-2010 (AHEI-2010), which evaluates overall dietary habits. Waist-to-hip ratio was tracked over 21 years at five different time points.
Brain health was assessed using two advanced imaging techniques: diffusion tensor imaging (DTI) and resting-state functional magnetic resonance imaging (fMRI).
These methods helped researchers examine brain connectivity and white matter integrity. Cognitive abilities such as memory, problem-solving, and language fluency were also tested.
The results showed that people with healthier diets in midlife had better brain connectivity later in life. Specifically, a higher AHEI-2010 score was linked to stronger connections between the hippocampus (a key memory region) and parts of the brain responsible for vision and coordination.
Brain scans also revealed that these individuals had healthier white matter, which helps brain regions communicate efficiently. This was associated with better memory and thinking skills.
On the other hand, a higher waist-to-hip ratio in midlife was linked to poorer brain health. People with more abdominal fat had weaker white matter structure, particularly in brain areas involved in memory and decision-making. This structural decline was also associated with lower cognitive performance.
These findings suggest that both diet and body fat distribution in midlife can predict brain health in older age.
The study highlights the importance of adopting a healthy diet and maintaining a balanced body weight early in life to help protect against cognitive decline.
Dr. Sharmili Edwin Thanarajah from Goethe University Frankfurt, who wrote a commentary on the study, pointed out some limitations. One concern is that most of the participants were male, with only 20% being female.
Since men and women store body fat differently and have different metabolic responses, more research is needed to understand how these findings apply to women.
Another factor is alcohol consumption. The study found that people with lower diet quality tended to drink more alcohol, but it is unclear whether alcohol itself plays a separate role in brain aging. Alcohol affects white matter integrity and vascular health, so future studies should examine this more closely.
Thanarajah also emphasized that improving public health requires more than just individual choices. With 43% of adults and 20% of children worldwide being overweight, the modern food environment makes it difficult for people to consistently eat healthy. Efforts to promote better diets need to go beyond personal responsibility and include policies that encourage healthier food options.
This study strengthens the idea that what we eat in midlife—and how our body fat is distributed—can shape our brain health decades later.
While the results suggest that a better diet and a lower waist-to-hip ratio may help preserve cognitive function, more research is needed to prove direct cause-and-effect relationships. Future intervention studies could help confirm whether changing diet and body composition in midlife can actively slow brain aging.
For now, the message is clear: eating a healthy diet and maintaining a balanced body shape during midlife may be key steps toward keeping the brain sharp in later years.
If you care about weight loss, please read studies about orange that could help obesity, and a berry that can prevent cancer, diabetes and obesity.
For more health information, please see a recent study that whole grains are key to managing waist size, blood pressure, and blood sugar.
The research findings can be found in JAMA Network Open.
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