Your body needs to remain in a state of balance. Constantly. Almost everything your body does is to bring your body to its desired state of balance. This need for your body to be in balance is also known as homoeostasis. The notion of homoeostasis goes back to ancient Greek concepts of harmony, equilibrium and balance in all aspects of life and health. Empedocles conceived of the concept that all matter consisted of elements that were opposites and that harmony or balance was a necessary condition for survival.
For example, when you eat a meal full of fat and sugar, your sugar levels rise. Insulin is then secreted to flush the sugar and bring your sugar levels back into balance. The same thing happens when your temperature rises. Your body will work to bring it back to its desired state by making you perspire if the temperature is high or keep it warm by shivering. Occasionally the ability of the body to self-regulate is affected and requires external intervention – taking medicines to lower your temperature for example.
Your body has sensors which are similar to the concept of a thermostat. It is this sensor that detects minor changes in body conditions and kicks-starts the process of regaining balance. For example, your body temperature is regulated by sensors in your hypothalamus among other places.
Some of the key aspects of your body that are controlled are body temperature, blood pressure, blood flow, sugar levels, plasma ionised calcium levels, oxygen and carbon dioxide levels, blood oxygen levels, sodium levels, potassium levels and finally the amount of water in your body. You may oddly be familiar with many of them because when they are unbalanced, they create cravings. Salt, sugar, water are things you might have experienced cravings for in the past. The alarm bells ringing was your homoeostasis saving your life.