Hunger

Hunger is a derived statistic in Fallout 4 in Survival mode.

Characteristics
Hunger occurs if the Sole survivor does not eat food after a long enough period of time. It accumulates slowly at all times, and modifies Action points (AP) and SPECIAL stats. Higher hunger levels induces Fatigue. Most types of food will reduce hunger by some amount, though certain foods are more effective than others.

Stages of hunger
This table taken from FNV. Needs to be updated to FO4