Apparently so - if you have the fat gene, FTO, that exists in 50 percent of the world's population. Researchers from the University of California at Los Angeles, (UCLA) found this gene not only increases your propensity to be obese but also eats at your brain tissue.

On April 19, the UCLA study was published in the online edition of Proceedings of the National Academy of Science ( PNAS), a renowned American scientific journal.

The researchers used 3D "regional brain volume" maps to see the difference of brain tissue deterioration amongst "206 healthy elderly subjects."

The results showed that those with the gene variant had around 8 percent less brain tissue in the frontal lobes and 12 percent in the occipital lobes causing brain atrophy linked to dementia and Alzheimer's.

Paul Thompson, neurology professor at UCLA, led the study and said, "The results are curious. If you have the bad FTO gene, your weight affects your brain adversely in terms of tissue loss," and "if you don't carry FTO, higher body weight doesn't translate into brain deficits; in fact, it has nothing to do with it. This is a very mysterious, widespread gene."

Individuals with this "specific DNA sequence are heavier on average, and their waist circumference is half an inch bigger. This is a shocking finding. Any loss of brain tissue puts you at greater risk for functional decline," Thompson continued,  "the risk gene divides the world into two camps - those who have the FTO allele and those who don't."

The good news is that "carriers of the risk gene can exercise and eat healthily to resist both obesity and brain decline."

With "half of the world carrying this dangerous gene," the bright side is that individuals can counteract their risk by maintaining "a healthy lifestyle." Thompson added, "it's vital to boost your brain health by being physically active and eating a balanced diet."

This study could impact the way "anti-dementia drugs being developed to combat brain aging." In the interim, get fit.

Full study,  "A commonly carried allele of the obesity-related FTO gene is associated with reduced brain volume in the healthy elderly":