Neural explanations for obesity assume that obesity is the result of physical differences in the brain. In obesity, problems with neural circuits and imbalances in brain chemistry have been implicated. For example, the arcuate nucleus (a collection of neurons in the hypothalamus) is responsible for monitoring sugar levels in the blood. The arcuate nucleus is activated when energy levels become low, sending messages that produce the desire to eat. This means that if there is any malfunction in this area, overeating and obesity can occur.