The process by which the body responds to stresses in order to regain homeostasis or the ability of a bodily system of a living organism to adjust its internal environment to maintain a state of dynamic constancy; such as, the ability of warm-blooded animals to maintain a stable temperature: Allostasis is the process of achieving and maintaining stability with physiological or behavioral changes which organisms actively adjust to both predictable and unpredictable events; for example, if a person walking in the desert is hot, the body will sweat and it will quickly become dehydrated.

With allostasis during dehydration, sweat occurs as only a small part of the process with many other systems also adapting their functioning, both to reduce water use and to support the variety of other systems that are changing to aid this and so in this case, kidneys may reduce urine output, mucous membrane in the mouth, nose and eyes may dry out and sweat output will decrease