Permanent Fat, Galbanic C, Macerinic S.

Added permanent fat, a new value that's added to your total fatness. It cannot be removed through normal means and persists between rounds. Its value is recorded when leaving through cryo or at the end of a round if one is alive.
Added Galbanic Compound, a fermichem that causes massive fatness gain and adds permanent fatness. Overdose increases these effects. Addiction causes you to still swell up with normal fat, makes you hungrier, less full and makes you gain more from all sources (these effects end when the addiction does).
Added Macerinic Solution, a fermichem that can quickly remove fat and even permanent fat.

code/modules/client/preferences.dm

@@ -105,6 +105,7 @@ GLOBAL_LIST_EMPTY(preferences_datums)
 
 	//GS13
 	var/starting_weight = 0				//how thicc you wanna be at start
+	var/permanent_fat = 0				//If it isn't the consequences of your own actions
 	var/wg_rate = 0.5
 	var/wl_rate = 0.5
 	var/voice = "human"
@@ -2997,6 +2998,7 @@ GLOBAL_LIST_EMPTY(preferences_datums)
 	//GS13
 	character.fatness = starting_weight
 	character.fatness_real = starting_weight
+	character.fatness_perma = permanent_fat
 	character.weight_gain_rate = wg_rate
 	character.weight_loss_rate = wl_rate
 

code/modules/client/preferences_savefile.dm

@@ -392,6 +392,7 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 	S["age"]				>> age
 	S["body_size"]			>> body_size
 	S["starting_weight"]	>> starting_weight
+	S["permanent_fat"]		>> permanent_fat
 	S["wg_rate"]			>> wg_rate
 	S["wl_rate"]			>> wl_rate
 	S["hair_color"]			>> hair_color

code/modules/reagents/chemistry/holder.dm

@@ -321,6 +321,12 @@
 					else if(stage in R.addiction_stage4_end to INFINITY)
 						to_chat(C, "<span class='notice'>You feel like you've gotten over your need for [R.name].</span>")
 						SEND_SIGNAL(C, COMSIG_CLEAR_MOOD_EVENT, "[R.type]_addiction")
+						
+						//GS13 on reagent addiction removal
+						if(istype(R, /datum/reagent/fermi_fat))
+							var/datum/reagent/fermi_fat/F = R
+							F.addiction_remove(C)
+						
 						cached_addictions.Remove(R)
 					else
 						SEND_SIGNAL(C, COMSIG_CLEAR_MOOD_EVENT, "[R.type]_overdose")