 The melanocaution system has been known to be involved in both weight gain and weight loss, however it was unclear how this system could be manipulated to treat obesity. This study found that chronic inhibition of certain neurons in the brain caused obesity, while chronic activation did not have any effect. Additionally, overexpression of the melanocaution system did not help prevent or reverse obesity. This suggests that the melanocaution system may protect against weight loss, which explains why it is difficult to manipulate the system to treat obesity. This article was authored by Hong Li Li, Yuan Zhongxu, Yang Yang Jiang, and others.