A surprising brain discovery could help explain why we overeat fatty foods

Obesity is a widespread health issue across the globe, increasing the risk of diabetes, cardiovascular disease, and other metabolic disorders. Researchers are now focusing on the impact of high-fat foods, which are commonly found in grocery stores, on our eating behavior. Overeating typically begins in the brain, as appetite is primarily controlled by neural systems. However, the exact way dietary fat interacts with these systems remains unclear.

Professor Shigenobu Matsumura of Osaka Metropolitan University's Graduate School of Human Life and Ecology led a research team to study this link, focusing on optic atrophy 1 (OPA1), a mitochondrial fusion protein found in hypothalamic MC4R neurons. OPA1 contributes to maintaining mitochondrial function and energy metabolism. The team compared wild-type mice with those lacking OPA1 in MC4R neurons and provided them with unlimited access to soybean oil, a source of dietary fat.

The study found that soybean oil increased OPA1 expression in male wild-type mice but not in females. Mice without OPA1 consumed more food, gained more weight as they aged, and ultimately developed obesity. When given the choice between standard chow and soybean oil, OPA1-deficient mice increased their fat intake and gained more weight, particularly females.

The researchers also tested setmelanotide, an anti-obesity MC4R agonist, which successfully reduced appetite in both male and female mice with normal OPA1 levels. However, it was less effective in OPA1-deficient females.

Professor Matsumura concluded that these findings offer valuable insights into the mechanisms of obesity from a neuronal energy metabolism perspective. The sex differences observed in OPA1 responses and obesity susceptibility could help in designing obesity treatments tailored to sex-specific factors and promote personalized medicine approaches. The research was published in the FASEB Journal.