loss of energy stores in the form of glycogen, fats, and proteins, due to inadequate intake of nutrients or inability to digest, absorb, or metabolize ingested nutrients
Occurs after a prolonged low calorie intake. Anything below 900 calories a day is termed a starvation diet. The body responds to starvation by shutting down "non-essential" systems (for example, menstruation ceases), and lanugo (see above) is also common. Eventually, starvation can lead to serious long-term medical problems and death.
a state of extreme hunger resulting from lack of essential nutrients over a prolonged period
Starvation is a severe reduction in vitamin, nutrient, and energy intake, and is the most extreme form of malnutrition. In humans, prolonged starvation (in excess of 1-2 months) causes permanent organ damage and will eventually result in death.
In glaciology, starvation is said to occur when a glacier retreats not because of temperature increases, but due to precipitation being so low that ice flow downwards into the zone of ablation exceeds the replenishment from snowfall. Eventually, the ice will move so far down that it either calves into the ocean or melts.