Many people focus on body weight when thinking about health. Doctors often encourage people to lose weight to lower the risk of heart disease, diabetes, and other serious illnesses.
However, scientists are now discovering that where fat is stored in the body may be even more important than overall weight itself.
A new long-term study suggests that a specific type of fat called visceral fat may play a major role in how quickly the brain ages.
Visceral fat is the deep fat that surrounds organs inside the abdomen. Unlike fat stored just under the skin, visceral fat is hidden deep inside the body and is strongly linked to metabolic problems such as insulin resistance, diabetes, inflammation, and high blood pressure.
Researchers have long suspected that visceral fat may also affect brain health, but until now there has been limited long-term evidence showing how this process happens over many years.
Now, scientists have completed one of the largest and longest MRI studies ever conducted on this topic. The findings suggest that keeping visceral fat levels lower over time may help slow brain shrinkage and preserve memory and thinking abilities during aging.
The study was published in the journal Nature Communications.
The research was led by Professor Iris Shai from Ben-Gurion University of the Negev, who also works with Reichman University and Harvard University.
The study followed 533 middle-aged women and men for between five and sixteen years. Participants had previously taken part in several large dietary clinical trials, including DIRECT, DIRECT-PLUS, CASCADE, and CENTRAL.
Researchers used advanced MRI scans to repeatedly examine both the abdomen and the brain throughout the study period. The team measured changes in visceral fat, brain structure, and cognitive performance over many years.
Participants also completed cognitive testing using the MoCA test, which measures memory, attention, language, and thinking skills.
The results revealed a strong relationship between lower visceral fat accumulation and healthier brain aging.
People who maintained lower levels of visceral fat over time showed better preservation of total brain volume and gray matter volume. Gray matter is especially important because it contains many of the brain’s nerve cells involved in memory, thinking, and decision-making.
Researchers also found better preservation of a brain region called the hippocampus. The hippocampus plays a critical role in memory and learning and is one of the first areas affected in Alzheimer’s disease and dementia.
At the same time, people with lower visceral fat showed slower enlargement of the brain’s ventricles. Enlarged ventricles are considered a common sign of brain atrophy, which means shrinking or loss of brain tissue during aging.
The researchers discovered that people with persistently high levels of visceral fat experienced faster brain volume loss, especially in the hippocampus.
Importantly, the findings were not linked to body weight alone.
Scientists found that body mass index, commonly called BMI, did not show the same strong relationship with brain aging. Fat stored under the skin also did not appear to have the same harmful effect.
This suggests that visceral fat may be biologically different from other types of body fat and may affect the brain through unique metabolic pathways.
One of the most important discoveries involved glucose control.
The study found that fasting blood sugar levels and HbA1c, a marker of long-term blood sugar control, were the strongest predictors of brain changes over time.
Researchers believe this supports the idea that insulin resistance and poor glucose regulation may damage the brain by reducing blood flow, harming blood vessels, and weakening the protective blood-brain barrier.
These changes may speed up degeneration of brain tissue and increase the risk of memory decline.
Interestingly, cholesterol and inflammation markers did not show the same strong relationship with brain aging in this study.
The researchers also found something encouraging.
Even modest reductions in visceral fat during an 18-month dietary intervention were linked to better brain preservation five and ten years later. This was true even after adjusting for overall weight loss.
In other words, reducing harmful abdominal fat itself appeared more important than simply losing body weight.
Dr. Dafna Pachter, the study’s first author, explained that body weight alone does not fully capture the deep metabolic changes happening inside the body.
The findings suggest that focusing on metabolic health and abdominal fat may be more useful for protecting brain health during aging.
The study is important because it used repeated MRI scans over many years, allowing researchers to track real structural brain changes over time rather than relying on short-term observations.
Still, researchers caution that more work is needed to fully understand how visceral fat damages the brain and whether specific diets, medications, or lifestyle changes may best reduce these risks.
However, the findings provide growing evidence that protecting brain health may begin much earlier in life than many people realize.
The research suggests that controlling blood sugar, improving insulin sensitivity, and reducing deep abdominal fat in midlife could potentially help lower the risk of dementia and cognitive decline later in life.
Overall, the study highlights that healthy aging may depend not only on maintaining a healthy weight but also on reducing the hidden fat deep inside the abdomen that quietly affects metabolism and brain health over many years.
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