Research by a group at Nagoya University has revealed that the so-called "middle-age weight gain" is thought to be caused by aging and overeating. The antennae of nerve cells in the brain that promote metabolism to shrink.
This makes it difficult to issue commands to stimulate metabolism. It is hoped that this will lead to the development of treatments for obesity. The research was carried out on rats at the Graduate School of Medicine in Nagoya, Japan. The study was published in the Journal of the Japanese Medical Association.