The hypothalamus is a portion of the brain that contains a number of small nuclei. These nuclei have a bunch of different functions. One of the most important functions of your hypothalamus is to link your nervous system to your endocrine system. These two systems work together for your body. The nuclei in the hypothalamus regulate the basic needs of your body, sleep hunger, thirst. So when you dont have enough food in your body, that little part of your brain is telling your nervous and endocrine system that you are in need of food. Hope i helped :)
