Recently, I wrote a blog about a study showing that being fat makes you stupid and lazy. Now come reports that overweight and obese people have less brain tissue than lean people.

Scientists used brain scans to determine the amount of brain tissue in 94 people over the age of 70. Their findings appear online in the journal Human Brain Mapping. They found that obese individuals had 8 percent less brain tissue and their brains looked 16 years older than the brains of people at normal weights. Overweight people had 4 percent less brain tissue and their brains appeared eight years older.

The loss of tissue occurred in several important areas of the brain. In obese people, losses affected the following areas:

• Frontal lobes: Critical for planning, follow-through, and impulse control. Losing brain tissue here makes it harder for people to stick with a diet, which may explain why some people just keep getting fatter.

• Anterior cingulate gyrus: The brain’s gear shifter, allowing you to go from thought to thought. When this area is out of whack, it can cause you to get stuck on certain thoughts or compulsive behaviors, such as bingeing on chocolate chip cookies or double-decker burgers.

• Hippocampus: This is where long-term memories are processed.

• Temporal lobes: One of the brain’s memory centers.

• Basal ganglia: Sets anxiety level and is involved with movement.

In the overweight crowd, brain loss occurred in the following areas:

• Basal ganglia: See above.

• Corona radiata: White matter that speeds communication between different areas of the brain.

• Parietal lobe: Involved with sense of touch and direction.

Overall, the loss of brain tissue puts people at increased risk for Alzheimer’s disease, dementia, and other brain disorders. This doesn’t bode well for the 66 percent of Americans who are considered overweight or obese. About one-third of Americans fall tip the scales in the obese category.

The good news is that you can do something to improve brain function and help prevent Alzheimer’s disease and other types of brain problems. Getting your weight under control with a brain healthy diet and regular exercise can greatly reduce your risk. Don’t lose your brain!