A groundbreaking long-term MRI study at Ben-Gurion University of the Negev (BGU) in Beersheba shows that lower accumulation of abdominal (visceral) fat is linked with a significant slowing of brain atrophy, preservation of key brain structures, and better cognitive performance in late midlife – independent of weight loss.
The findings suggest that the relationship between abdominal fat and brain aging is mediated primarily through glucose control and insulin sensitivity.
The study is the first to link repeated MRI-based measurements of cumulative visceral fat with long-term brain aging and cognition. The study’s findings were published in the respected journal Nature Communications under the title “Sustained visceral fat loss is associated with attenuated brain atrophy and improved cognitive function in late midlife.”
The largest and longest study to date, linking cumulative exposure to visceral fat and brain measures assessed with MRI and the rate of brain aging and cognitive function, was led by BGU Prof. Iris Shai, who is also Dean of the School of Sustainability at Reichman University and an adjunct professor at Harvard University. Leipzig University in Germany and Tulane University in New Orleans also collaborated on the research.
Dr. Dafna Pachter, the study’s first author, said: “Weight alone is not a sensitive marker of the profound metabolic changes occurring in the body. We found that even when weight loss is modest, sustained reductions in visceral fat – as measured across the entire period – are associated with preservation of brain structure and a slower rate of atrophy.”
Body fat not necessarily bad
Body fat often gets a bad reputation, with people regarding it as always being harmful, but this isn’t true. It’s more than just a number on the scale or the calories you consume. There are several types; though often misunderstood, fat carries out functions that are both beneficial and necessary for good health. It’s the location, the types, the amount stored in your body, and the ratio between the various kinds of fat that can be dangerous.
The main types are “brown fat,” “white fat,” and “visceral fat.” The first is composed of iron-rich mitochondria (membrane-bound subunits within a cell that perform specific functions essential for the cell’s survival) that generate most of the chemical energy needed to power the cell’s biochemical reactions. This is what produces its color.
Brown fat stores and burns energy to help regulate body temperature by producing heat without shivering. You can’t directly increase or decrease brown fat in the body, but you can activate the fat cells through exposure to lower temperatures, nutrition, and physical activity. Brown fat is found mostly in the neck, upper back, and shoulders. The exact final amount in adult individuals varies based on genetics, diet, and lifestyle.
Certain healthy fats, like the omega-3 fatty acids found in salmon, tuna, mackerel, sardines, herring, walnuts, flaxseed, and fish oil supplements, have been shown to promote brown fat activity. This can help increase the amount of energy your body burns at rest, which is beneficial for weight loss and long-term weight management, the researchers said.
White fat stores excess calories to be used as energy later. It helps the body absorb and store fat-soluble vitamins A, D, E, and K., and plays a role in hormone regulation by producing and releasing hormones throughout the body, such as leptin and insulin. White fat is located under your skin that you can pinch and feel on your arm.
However, visceral fat surrounds your liver, stomach, and intestines behind the abdominal wall. If you have an excess, Shai explained, it puts pressure on these organs and promotes chronic inflammation in the body. This inflammation can trigger a cycle of metabolic issues, increasing the risk of conditions like type-2 diabetes, cardiovascular disease, stroke, and high cholesterol – even in lean people.
Visceral fat is a type of body fat stored deep within the abdominal cavity, surrounding internal organs like the liver, pancreas, and intestines.
You can identify an excess primarily by measuring waist circumference at the navel – over 90 centimeters for women or 102 cm. for men. You can also estimate if you have excess visceral fat by dividing your waist measurement by your hip measurement. A ratio higher than 0.85 for women or 0.90 for men suggests high visceral fat.
An “Apple” shape – gaining weight primarily in the abdomen/trunk is more closely associated with visceral fat than a “pear” shape. An abdominal ultrasound can hint at the amount of visceral fat inside.
However, the most exact – though expensive – methods for your health fund to measure visceral fat are CT scans or MRIs, which can distinguish it from subcutaneous fat, plus blood tests for elevated triglycerides, high blood sugar, or high liver fat markers.
Fortunately, while visceral fat is dangerous, it is also highly responsive to lifestyle, including avoiding overly processed foods and instead eating more fiber; doing regular aerobic exercise, including walking, and resistance training; managing stress to lower cortisol; and getting seven to nine hours of quality sleep. Improving your lifestyle this way can significantly reduce your visceral fat in six months, but if you don’t persevere, it can return, Shai warned.
The study is based on advanced MRI imaging of the brain and abdomen, including 533 women and men in late midlife who were followed for five to 16 years after participating in four large, long-term, controlled dietary clinical trials: DIRECT, CASCADE, CENTRAL, and DIRECT-PLUS.
During follow-up, repeated MRI measurements of visceral fat and brain structures were conducted, along with cognitive assessment using the Montreal Cognitive Assessment (MoCA) test – a widely used 10-minute, 30-point screening tool designed to detect mild cognitive impairment (MCI) and early Alzheimer’s.
The findings show that lower accumulation of visceral fat over the years was associated with higher MoCA scores, as well as preservation of total brain volume, gray matter volume, and the Hippocampal Occupancy Score – a sensitive marker of brain aging and memory. In parallel, a slowing in the expansion of the brain ventricles was observed, a process that constitutes a well-established marker of brain atrophy.
“The findings point to glucose control and reduction of visceral abdominal fat as measurable, modifiable, and achievable targets in midlife – with real potential to slow brain degeneration and reduce the risk of cognitive decline,” Shai said.
A unique longitudinal follow-up, which included three brain MRI scans over five years in a subgroup of participants, showed that persistently elevated levels of visceral fat over time were associated with a faster rate of brain volume loss, particularly in the hippocampus, and with accelerated enlargement of the brain ventricles.
These associations were not observed for subcutaneous fat, neither superficial nor deep, nor for body mass index (BMI), highlighting the biological specificity of visceral fat.
Moreover, the study found that reductions in visceral fat during an 18-month dietary intervention predicted better preservation of brain structures five and 10 years later, even after adjustment for weight loss and other factors. In other words, the reduction in abdominal fat itself – rather than weight loss per se – was the factor predicting long-term brain outcomes.
“The clinical implications of this work are significant. Given the global burden of obesity, cognitive decline, and dementia, identifying modifiable risk factors for cognitive decline is a critical public health priority,” they concluded.
