It can feel hard to stop eating pizza; after all, it is delicious. But according to new research, eating high fat foods like pizza might actually trigger a biological mechanism that blocks the brain from letting its body know when it is time to stop.
In a study published this week in the journal Science Translational Medicine, researchers found that when they fed mice a high-fat diet, the animal’s brains produced an enzyme (named MMP-2) which clips receptors for the hormone that regulates hunger, leptin. When leptin cannot bind to the receptors in your brain, it can’t fire the neurons to your stomach to tell it it is full, and that it is time to stop eating.
Rafi Mazor, a research scientist in the Department of Bioengineering at the University of California San Diego and the lead researcher said it was the first time this kind of destructive molecular mechanism has been observed and described, adding that the research could lead to a “new field of study for metabolic disease." (Leptin resistance is a known process associated with obesity, but the way it functions is not fully understood.)
In the early stages of being overweight, the neural pathways are still intact, added Geert Schmid-Schonbein, a bioengineering professor from UC San Diego. Eventually, the receptors get destroyed, he said, but they can regenerate to an extent. Mazor and his colleagues also found, however, that it was also possible to block the destructive enzyme — which would enable leptin to bind to the appropriate receptors, and let the brain tell the body when it is sated.
In the future, the researchers hope that doctors might be able to treat “leptin resistance” in humans by blocking the enzyme, and are calling for a clinical trial to test whether MMP-2 inhibitors could help people lose weight. Further research may explore which other pathways — in addition to leptin and its receptors — might undergo a similar destructive process, and what the consequences might be, according to the authors. But, Mazor added, "there is still a lot of work to do to better understand receptor cleaving and the loss of cell function while on a high-fat diet."