Maturation is the increase in the state of maturity. The dynamic energy budget theory uses this concept to quantify changes in the life history of individuals. If the investment into maturation exceeds a threshold value, an life history event is triggered. This investment of reserve into maturation technically represents an accumulation of information, but not of mass or energy.So the material products of this investment leave the organism, mostly in the form of carbon dioxide, nitrogen-waste and water.

Examples of life history events are

• Birth: food acquisition is initiated. Individuals leave the embryonic stage and enter the juvenile stage.
• Puberty: allocation to reproduction is initiated, while that to maturation is ceased. Individuals leave the juvenile stage and enter the adult stage
• Division of unicellular organisms. Cells divide into two (or more) daughter cells. This frequently follows after an early trigger to duplicate DNA (yet another life history event).

In practice these events take some time, but for simplicity's sake they are represented as point events in the DEB theory.

Birth typically preceeds puberty, but not so in aphids, which have (formally) a negative juvenile period. In Oikopleura birth and puberty coincide, so they have a juvenile period of length zero.

Some organisms (most mammals, some sharks, peripatus) don't producs eggs but have foetuses that recieve reserve from the mother via a placenta.This does not count as feeding in the context of the DEB theory; because the gut system is not active and no transformation from food to reserve takes place, only a tranfer of reserve from the mother to the foetus.