Editing Saturation

'''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.

==General mechanics==
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. Adult [[human]]s can hold 1.0 nutrition. For them, 1.0 nutrition is 100% saturation. This property is almost entirely controlled by [[body size]] <code> 1.0 * body_size</code>.<br>Human teenagers (ages 13 - 17) are a special exception; they are smaller than adults, but have a special multiplier to max nutrition so that they equal adults.
# 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 a variety of other factors.

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.

{| class="wikitable"
|-
! Label
! Saturation
! Mood modifier<br>(Humans)
! Production Rate<br>(Animals)
|-
| Fed
| Greater than 25%
| (none)
| ×100%
|-
| Hungry
| 12.5% to 25%
| -6
| ×50%
|-
| Ravenously Hungry
| >0% to 12.5%
| -12
| ×25%
|-
| Malnourished
| 0%
| -20
| ×0%
|}

Speed of animals' production ([[wool]], [[milk]], [[egg]]s 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.

=== Malnutrition ===
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%).

==Saturation Changes==
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):

{| class="wikitable"
|-
! Saturation
! Threshold range
! Change per hour
! Change per day
! Game time in state<ref>Game time spent in the state from the upper threshold before crossing the lower threshold, assuming nothing is eaten</ref>
! Game time since 100% food<ref>Game time spent before entering the state, assuming nothing is eaten and the starting saturation is 100%</ref>
|-
| Fed
| 100% - 25%
| -6.67%
| -160%
| {{#expr: 0.75 / (1.6/24) round 3}} hours  <!-- (% Saturation) / (Hunger Rate per hour) --->
| {{#expr: 0 round 3}} hours
|-
| Hungry
| 25% - 12.5%
| -3.33%
| -80%
| {{#expr: 0.125 / (0.8/24) round 3}} hours 
| {{#expr: (0.75 / (1.6/24) ) round 3}} hours  
|-
| Ravenously Hungry
| 25% - >0%
| -1.67%
| -40%
| {{#expr: 0.125 / (0.4/24) round 3}} hours 
| {{#expr: (0.75 / (1.6/24) ) + ( 0.125 / (0.8/24) ) round 3}} hours
|-
| Malnourished
| 0%
| N/A <ref>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.</ref>
| N/A
| 50 hours
| {{#expr: (0.75 / (1.6/24) ) + ( 0.125 / (0.8/24) ) + (0.125 / (0.4/24) )  round 3}} hours
|}
{{Reflist}}

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 Modifiers==
{{stub|section=1|reason=Rough, possibly incomplete list. Also needs verification}}
The following factors will modify hunger rate:

===Hunger rate factor===
All hunger rate ''factor'' modifiers stack additively. Once added up, they stack multiplicatively with other modifiers to hunger.

* [[Gut worms]] - {{++|100%}} hunger rate
* [[Smokeleaf|Stoned on smokeleaf]] - {{++|30%}} hunger rate
* [[Go-juice#Withdrawal|Go-juice withdrawal]] - {{++|50%}} hunger rate
* [[Malnutrition]] -
** Trivial: {{++|50%}} hunger rate
** Minor: {{++|60%}} hunger rate
** Moderate: {{++|60%}} hunger rate
** Severe: {{++|60%}} hunger rate
* Hunger pangs [[persona trait]]{{RoyaltyIcon}} - {{++|50%}} hunger rate
* [[Neural supercharger]] {{IdeologyIcon}} - {{++|20%}} hunger rate
* [[Growth vat#Summary|Bio-starvation]] (outside of [[growth vat|vat]]){{BiotechIcon}} - {{++|50%}} hunger rate

===Other multipliers===
All of these modifiers stack multiplicatively with each other and with the hunger rate factor listed above.
* [[Gourmand]] trait - {{Bad|x150%}} hunger rate 
* Stomach implants:
** [[Reprocessor stomach]]{{RoyaltyIcon}} - {{Good|x75%}} hunger rate
** [[Nuclear stomach]]{{RoyaltyIcon}} - {{Good|x25%}} hunger rate
* [[Genetic]] [[metabolic efficiency]] {{BiotechIcon}} - Positive metabolic efficiency reduces hunger by {{---|10%}} per point. Negative metabolic efficiency increases hunger by {{++|25%}} per point. Positive and negative metabolic efficiencies are added/subtracted from each other. Metabolic efficiency is effectively capped at -5 ({{Bad|x225%}}) and +5 ({{Good|x50%}}). The final metabolic efficiency is used to determine hunger rate, and will stack multiplicatively with other hunger rate modifiers.

Despite its name and description, the [[Metabolism]] stat has no impact on hunger rate.

== Overeating ==
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.

==Analysis==
An adult baseline human will eat roughly 2 [[simple meal]]s, 32 units of [[pemmican]], or 32 units of [[raw food]] per day.

Cooking food effectively "creates" nutrition. For example, a [[simple meal]] is worth 0.9 nutrition, and only costs 0.5 nutrition 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 {{icon small|milk}} {{Q|Cow|Daily Milk Average}} per day, or {{#vardefineecho:milk_nutr_per_day|{{#expr:{{Q|Cow|Daily Milk Average}}*0.05}}}} [[nutrition]] in milk per day. A cow consumes {{Q|Cow|Real Hunger Rate}} 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 meal]]s or even [[simple meal]]s, it can feed itself with plenty of food to spare. This gets even sillier with [[chicken]]s, which produce more nutrition in [[egg]]s 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:
{| class="wikitable"
|-
! Hours survived !! State
|-
| 9.75 || Fed
|-
| 3.75 || Hungry
|-
| 7.50 || Ravenously hungry
|-
| 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:
{| class="wikitable"
|-
! Hours survived !! State
|-
| 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.

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