The Body Mass Index (BMI) has long been used as a primary tool to measure weight and general health, but a recent study published in Nature Mental Health has radically changed this concept.

Researchers from The Hong Kong Polytechnic University (PolyU) analyzed data from over 18,000 individuals in the UK Biobank database, using advanced body and brain imaging techniques. They revealed that the location of fat accumulation is far more important than just body size or weight. These findings represent a turning point that calls for redefining the concept of health “fitness.”

Visceral Fat and Its Impact on the Brain

Not all fat carries the same risks. Fat that accumulates under the skin in limbs or thighs is less harmful, while deep visceral fat surrounding the liver, intestines, and pancreas is directly linked to declines in cognitive functions such as memory, processing speed, and logical thinking.

More dangerously, this fat alters brain structure and neural connections, affecting control and concentration abilities.

The reason lies in the nature of visceral fat, which is not a dormant energy store but an active hormonal tissue that continuously secretes inflammatory molecules.

These molecules, such as cytokines, can cross the blood-brain barrier, causing chronic low-grade inflammation that damages neurons and accelerates brain aging.

Why BMI Is Not Enough

The study clarifies that BMI is insufficient for assessing health risks, as a person may appear to have a “normal” weight but carry dangerous internal fat accumulation, known as TOFI (Thin Outside, Fat Inside). This means health evaluation requires looking at fat distribution, not just the number on the scale.

More Accurate Measurement Methods

• Waist circumference: An easy and quick method. Exceeding 102 cm in men and 88 cm in women indicates increased visceral fat.
• Magnetic Resonance Imaging (MRI): The most accurate method but expensive, mostly used in research or special cases.

Steps to Reduce Deep Fat

• Balanced nutrition: Adopting a Mediterranean diet rich in fiber and antioxidants, increasing light proteins, and reducing sugars and trans fats. Soluble fibers (oats and legumes) effectively help reduce internal fat.
• Physical activity: Aerobic exercises like walking, running, and cycling efficiently burn visceral fat, while resistance training increases muscle mass and improves insulin sensitivity.
• Sleep and stress management: Lack of sleep raises cortisol, which promotes fat storage around organs. Good sleep of 7 to 9 hours daily and relaxation practices reduce these risks.

In short, maintaining brain health is not only about losing weight but controlling where fat accumulates, especially visceral fat, which is the hidden enemy to both body and mind health.