Exercise appears to exert similar effects on brain function by boosting insulin sensitivity and fighting inflammation.

CNN: Cutting calories may boost your memory

Norman Pollock, a researcher at Georgia Health Sciences University and a co-author of the study, says one explanation may be that fiber is associated with higher levels of a protein hormone that improves insulin sensitivity, which in turn lowers levels of inflammation.

WSJ: The New Science Behind America's Deadliest Diseases

Experts believe that, as Floel's study suggests, increased inflammation and a drop in insulin sensitivity (which is known as insulin resistance) may help explain why obesity and type 2 diabetes have been linked to worse mental performance and a greater risk of Alzheimer's disease.

CNN: Cutting calories may boost your memory

Some patients will be effectively treated with medications such as metformin that increase peripheral sensitivity of organs to insulin.

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