The result is all the more interesting as the BMI does not allow us to distinguish this deep fat. The researchers therefore invite us to look beyond the number displayed on the scale: in mid-life, sustainably reducing visceral fat could be an interesting lever for preserving both metabolic and brain health.
It’s not necessarily the weight that matters most
With age, the stomach sometimes changes without the scale moving much. This phenomenon is not trivial: part of the fat can gradually move towards the inside of the abdomen. This is the
visceral fatdifferent from the fat located just under the skin. It particularly surrounds organs such as the liver, intestine or pancreas. And unlike subcutaneous fat, it cannot be identified simply by looking at your figure.
This is precisely what Dr. Dafna Pachter, first author of the study, from Ben-Gurion University of the Negev, points out:
“Weight alone is not a reliable indicator of the profound metabolic changes occurring in the body. We found that even with modest weight loss, sustained reduction in visceral fat – measured over the entire period – is associated with preservation of brain structure and slowing of atrophy.”.
To reach this conclusion, the team led by Professor Iris Shai, from the Harvard TH Chan School of Public Health and Ben-Gurion University of the Negev, used data from participants who took part in diet and lifestyle trials.
In total, 533 adults aged approximately 61mostly overweight, received abdominal and brain MRIs as well as a cognitive test. Some participants were then followed for several years, up to 16 years old. And a signal appears.
Less visceral fat, a brain that seems to resist better
People with the least exposure to visceral fat over the years had larger total brain volume and more gray matter. The researchers also observed a better Hippocampal Occupancy Scorea particularly interesting indicator because the hippocampus plays an essential role in memory.
Conversely, people who retained more visceral fat had more signs of brain atrophy. The brain’s ventricles, chambers that tend to enlarge when the brain loses volume, also grew faster.
The result is all the more striking as neither BMI nor subcutaneous fat showed the same association with these brain markers. In other words, two people of comparable weight may not have the same metabolic profile nor, potentially, the same risk linked to brain aging.
At the house of 295 participants With three measurements of abdominal fat, greater cumulative exposure to visceral fat was associated, years later, with lower scores on standardized cognitive tests (MoCA and MoCA-Memory Index). And in a subgroup of 188 people who received three brain MRIsthose who retained the most visceral fat showed a more rapid decrease in brain volume, particularly in the hippocampus.
A question then remained unanswered: how could this deep abdominal fat act on the brain?
Blood sugar trail could explain part of the story
The researchers analyzed several blood markers to look for mechanisms likely to link visceral fat and brain aging. Two parameters particularly stand out: fasting blood sugar And
HbA1ca marker to assess the balance of blood sugar levels over several weeks.
This observation is consistent with another result from the same research program. In a study published in
Trafficthe researchers found that
every 10% reduction in visceral fat was associated with a 28% lower risk of type 2 diabetes ten years laterincluding in people who have regained all or part of the weight lost.
The two studies therefore tell a similar story: the scale does not necessarily summarize the metabolic benefits obtained when part of the visceral fat disappears sustainably.
In the initial tests, which lasted 18 to 24 monthsthe amount of visceral fat had decreased by an average of 24%. Years later, this reduction was associated with greater brain volume, independent of overall weight loss.
For Professor Iris Shai, these results indicate levers on which it would be possible to act:
“These results show that controlling blood sugar and reducing visceral abdominal fat are measurable, modifiable and achievable goals in our 40s and 50s, with real potential to slow brain degeneration and reduce the risk of cognitive decline.”.
An essential nuance, however: the study shows an association, and not proof that a reduction in visceral fat alone would prevent aging or a neurodegenerative disease.
Can we act on this invisible fat?
Researchers are obviously not proposing a “miracle diet”. Their approach is based on already known levers: regular physical activity and a Mediterranean-style diet, with a reduction in carbohydrates and a diet rich in polyphenolspresent in particular in green tea and nuts.
“This type of diet is particularly effective in targeting and reducing visceral fat reserves.says Iris Shai. “When combined with moderate, regular physical activity, it essentially programs the body to selectively burn internal fat that surrounds the organs rather than superficial tissues.”.
The interest of this work ultimately lies in a change of perspective. Health is not just about the weight displayed on the scale. Two people can have the same BMI and have very different amounts of visceral fat.
The researchers nevertheless recognize several limitations: the cohort was composed of 86% menmainly overweight, and the longest part of the follow-up was observational. These results will therefore need to be confirmed, particularly in women, younger people or those who are not overweight.
But an idea is already emerging: in midlife, taking care of your metabolic health could concern much more than the heart or diabetes. It could also be a way to give our brains a few more years of breathing space.