Saturation is the game mechanic that controls Characters' needs for Food, and is directly tied to Eating, the game mechanic which fills that need. A character with a higher saturation value has eaten recently, and is more full than another character with a low saturation level. You can view saturation of all humans and tamed animals by viewing the "Food" bar and the corresponding mouseover text in the Needs tab.
Saturation is measured in units of nutrition. There are 2 distinct measures of saturation.
- Maximum nutrition, or how much nutrition a pawn can store at any one time. It is dependent on the body size of the species as well as the body size factor and food max factor according to the pawns life stage. The function is
species_body_size × body_size_factor × food_max_factor. For adult specimens body size factor and food max factor are both 1. An adult human (with a body size of 1) can therefore hold up to 1 nutrition.
- For young humans the formula results in:
- Baby (0-2 years): 1 × 0.2 × 0.625 = 0.125 maximum nutrition
- Child (3-12 years): 1 × 0.35 × 2.286 = 0.8001 maximum nutrition
- Teenager (13-17 years): 1 × 0.8 × 1.25 = 1 maximum nutrition (therefore same as adults)
- For young insects:
- Larva: species_body_size × 0.2 × 2 = species_body_size × 0.4
- Imature: species_body_size × 0.5 × 1.5 = species_body_size × 0.75
- For other young animals:
- Baby (birds): species_body_size × 0.1 × 6 = species_body_size × 0.6
- Baby (other): species_body_size × 0.2 × 3 = species_body_size × 0.6
- Juvenile: species_body_size × 0.5 × 1.5 = species_body_size × 0.75
- For young humans the formula results in:
- Hunger Rate, or how much nutrition a pawn loses per day. Adult baseline humans hunger at a rate of 1.6 nutrition per day. This is determined by species and the Hunger Rate Factor explained below.
In general, humans hunger more than similar animals. An alpaca has the same body size as a human, but only hungers at a rate of 0.44 nutrition per day. A megasloth is four times larger than a human, but hungers at the same rate. Generally, predators hunger slowly - a cougar eats less than half as much as a husky, for instance.
Levels of saturation
Characters' saturation level is grouped into four thresholds: Fed, Hungry, Ravenously Hungry, and Malnourished. Each threshold exhibits different effects on a character, especially their Thoughts.
The saturation level boundaries are indicated by small notches on the "Food" bar in the tab of eating pawns.
|Fed||Greater than 25%||(none)||×100%|
|Hungry||12.5% to 25%||-6||×50%|
|Ravenously Hungry||>0% to 12.5%||-12||×25%|
Speed of animals' production (wool, milk, eggs or chemfuel) is also dependent on the saturation level, as seen above. Note that production is completely stopped only when 0% saturation; the "malnutrition" ailment does not have a direct impact on animal products.
Once a pawn reaches 0% saturation, they will start becoming malnourished.
When malnourished, pawns gain severity in "malnutrition". Malnutrition is an ailment, with an entirely separate progression to hunger or saturation. When malnourished, malnutrition severity rises by 2% every hour, and once it reaches 100%, the pawn will die. When a pawn is fed, their malnutrition does not immediately go away, though a pawn will no longer gain malnutrition (as Saturation is no longer at 0%).
For as long as the malnutrition ailment is active, pawns will gain increased hunger. This does not increase the rate of malnutrition severity, just the amount of food eaten after a pawn has been fed.
Saturation goes down every tick (1/2500 of a game hour), depending on the character's current saturation and modifiers on their hunger rate.
The following table describes saturation changes of an adult baseline human (100% hunger rate, 1.6 nutrition/day, 1.0 max nutrition):
|Saturation||Threshold range||Change per hour||Change per day||Game time in state||Game time since 100% food|
|Fed||100% - 25%||-6.67%||-160%||11.25 hours||0 hours|
|Hungry||25% - 12.5%||-3.33%||-80%||3.75 hours||11.25 hours|
|Ravenously Hungry||25% - >0%||-1.67%||-40%||7.5 hours||15 hours|
|Malnourished||0%||N/A ||N/A||50 hours||22.5 hours|
- ↑ Game time spent in the state from the upper threshold before crossing the lower threshold, assuming nothing is eaten
- ↑ Game time spent before entering the state, assuming nothing is eaten and the starting saturation is 100%
- ↑ Malnourished does not impact saturation directly. Rather, it increases the "Malnutrition" ailment by 2% per hour, and when this reaches 100%, a pawn dies. This ailment will increase hunger rate of a pawn, but only when they have access to food again.
From 100% saturation, a human can survive up to 72.5 hours before dying from malnutrition.
Saturation is increased by eating food. For reference, 1 unit of raw food (rice, meat, etc.) gives 0.05 nutrition, or 5% of a human's saturation meter. A simple meal, fine meal, or nutrient paste meal gives 0.9 nutrition, or 90% of a human's meter.
Hunger Rate Factor
|This section is a stub. You can help RimWorld Wiki by expanding it. Reason: Verify (and add?) modifiers from biotech. Verify in which order the modifiers are applied..|
The following things will modify hunger rate:
All hunger rate factor offset modifiers stack additively. Once added up, they stack multiplicatively with other modifiers to hunger.
- Stoned on smokeleaf: +30%
- Go-juice withdrawal: +50%
- Gut worms: +100%
- Hypothermic slowdown:
- Moderate: −10%
- Serious: −40%
- Extreme: −95%
- Trivial: +50%
- Minor, Moderate, Severe and Extreme: +60%
- Hunger pangs persona trait: +50%
- Neural supercharger: +20%
- Bio-starvation (outside of vat): +50%
- Genetic metabolic efficiency :
- Positive sum of metabolic efficiency: −10% per point. Max. −50%
- Negative sum of metabolic efficiency: +25% per point. Max. +225%
All of these modifiers stack multiplicatively with each other and with the hunger rate factor offsets listed above.
- Psychic hangover: ×150%
- Gourmand trait: ×150%
- Stomach implants:
- Reprocessor stomach: ×75%
- Nuclear stomach: ×25%
- Life stages:
Despite its name and description, the Metabolism stat has no impact on hunger rate.
Bed Hunger Rate Multiplier
This value has a base value of 100% and only applies when sleeping in an affected bed. It it currently unknown exactly how this value applies.
- Sleep accelerator: +20%
Pawns will attempt to eat as their next action once their saturation level reaches 30% to avoid being hungry. Pawns make no effort to avoid "overeating", so any excess nutrition in the food is lost. A default pawn that eats a simple meal (0.9 nutrition) as soon as it is hungry (0.30 saturation) will go to 1.0 saturation and waste up to 0.20 nutrition of food (22% of the meal). In practice, the process of eating takes some time, so not all the food is wasted.
This effect is stronger in animals with lower body sizes - a Labrador retriever with 0.75 body size will get hungry at .1875 saturation and waste .3375 nutrition from the same simple meal. Smaller, more fungible food sources like berries or haygrass (0.05 nutrition) have less of this waste, as the waste will never exceed a single item's worth of nutrition.
This makes kibble and pemmican particularly useful as feed for smaller sized animals. These foods provide more nutrition than raw food, but won't be overeaten like a regular meal would.
An adult baseline human will eat roughly 2 simple meals, 32 units of pemmican, or 32 units of raw food per day.
Cooking food effectively "creates" nutrition. A simple meal is worth 0.9 nutrition, but only costs 0.5 nutrition of food to make. This gives simple meals a 180% nutrition efficiency, before the overeating described above.
Due to the low food consumption of animals, as well as the efficiency of meals, it is possible to violate the laws of thermodynamics. For example, a female cow produces 14 per day, or 0.7 nutrition in milk per day. A cow consumes 0.86 nutrition per day. While cows cannot consume milk, almost all animals can consume meals, no matter what the meal is made out of. So when a cow's milk is turned into nutrient paste meals or even simple meals, it can feed itself with plenty of food to spare. This gets even sillier with chickens, which produce more nutrition in eggs than it consumes per day, even before the eggs are cooked. (Note that chickens cannot eat their own eggs, and that they are very prone to overeating.)
Conserving food via malnutrition
In extreme situations, it may be advisable to stay in a hungry state to benefit from the reduced hunger. Note that this requires significant micromanagement to pull off. Forbid the food and unforbid it when pawns are about to fall unconscious.
Consider, for example, a human at 0% saturation and 0% malnourishment. This pawn has 0.9 nutrition (one simple meal) to eat.
If the food is eaten immediately, such human survives:
|50||Starving until death from malnourishment|
Giving a total of 71 hours alive.
If we instead let the human remain malnourished for 13.75 hours, before eating, the pawn survives:
|13.75||Starving up to 27.5% malnourishment (minor)|
|3.75||Fed state with 27.5–20% malnourishment (minor)|
|2.50||Fed state with 20–15% malnourishment (trivial)|
|2.50||Hungry state with 15–10% malnourishment (trivial)|
|5.00||Ravenously hungry state with 10–0% malnourishment (trivial)|
|50||Starving until death from malnourishment|
Giving a total of 77.5 hours alive.