New findings help explain how brain pathways control body weight

A study led by a scientific team at Beth Israel Deaconess Medical Center provides another important step in our understanding of the critical role that the brain's molecular pathways play in the development of obesity and related disorders.

The findings, reported in the Nov. 4, 2005 issue of the journal Cell, demonstrate for the first time that the neuronal pathways that help to keep body weight stable diverge at the melanocortin-4 receptor (MC4R) to regulate either food intake or energy expenditure.

This unexpected discovery helps to extend the understanding of the complex neurocircuitry behind body weight control, an endeavor that began more than a decade ago with the identification of the leptin hormone and which has been growing steadily ever since.

"Maintaining a stable body weight is a delicate balancing act between the amount of food eaten versus the number of calories burned," says Bradford B. Lowell, MD, PhD, of BIDMC's department of endocrinology, diabetes and metabolism who, together with Joel K. Elmquist, DVM, PhD, served as co-senior author of the study."The brain controls both food intake and calories expended with the purpose of keeping body weight stable. When something goes wrong with this process, obesity results. The findings of this new research provide us with more precise information about the neuronal pathways regulating this balance."

Lowell and Elmquist are associate professors of medicine at Harvard Medical School.