From the article:
It has been shown that deleting the BDNF gene causes significant problems, among them, dramatically increased appetite (hyperphagia) and severe obesity.
The new study shows that deleting the BDNF gene also impairs thermogenesis – the ability of cells to burn fat to produce heat. The study further reveals two distinct types of BDNF neurons – those that control appetite or satiety and those that control thermogenesis. Not only do these two groups play different biological roles, they are located in two separate sections of the paraventricular hypothalamus brain region.