(First set of ingame hours: Your save, 2 intelligence. Second set: Your save, 25 intelligence.)

Unable to reproduce with in-repo mods

• OS: Windows
  • OS Version: Windows 10 (22H2)
• Game Version: 0.G-8389-g1b170f1cae-dirty [64-bit]
• Graphics Version: Tiles
• Game Language: English [en]
• Mods loaded: [
  Dark Days Ahead [dda],
  Bionic Professions [package_bionic_professions],
  Disable NPC Needs [no_npc_food],
  Portal Storms Ignore NPCs [personal_portal_storms],
  Slowdown Fungal Growth [no_fungal_growth],
  Mythical Martial Arts [MMA],
  Bombastic Perks [bombastic_perks],
  Magiclysm [magiclysm],
  Aftershock [aftershock],
  Xedra Evolved [xedra_evolved],
  Mind Over Matter [mindovermatter],
  SpeedyDex [speedydex],
  Stats Through Kills [stats_through_kills],
  Stats Through Skills [StatsThroughSkills]
  ]

#72773 should at least cause high levels of weariness to turn off your powers.

Well, I loaded up the save using in-repo mods and activated Metabolic Hyperefficiency. One step immediately dropped me to Extremely Weary, and:

Also, the character was freezing to death for some reason.

• OS: Windows
  • OS Version: 10.0.19045.4170 (22H2)
• Game Version: 4808268 [64-bit]
• Graphics Version: Tiles
• Game Language: English [en]
• Mods loaded: [
  Dark Days Ahead [dda],
  Bionic Professions [package_bionic_professions],
  Disable NPC Needs [no_npc_food],
  Portal Storms Ignore NPCs [personal_portal_storms],
  Slowdown Fungal Growth [no_fungal_growth],
  Mythical Martial Arts [MMA],
  No name () [],
  Bombastic Perks [bombastic_perks],
  Magiclysm [magiclysm],
  No name () [],
  No name () [],
  No name () [],
  Aftershock [aftershock],
  Xedra Evolved [xedra_evolved],
  No name () [],
  Mind Over Matter [mindovermatter],
  No name () [],
  No name () [],
  No name () [],
  No name () [],
  No name () [],
  SpeedyDex [speedydex],
  Stats Through Kills [stats_through_kills],
  Stats Through Skills [StatsThroughSkills],
  No name () [],
  No name () []
  ]

Well, I loaded up the save using in-repo mods and activated Metabolic Hyperefficiency. One step immediately dropped me to Extremely Weary, and:

I updated to 4aef748 which includes your new PR mentioned above and I'm still not able to reproduce on MSVC (have not tried other versions).

PEBKAC: Triage(me) forgot to follow the reproduction steps.

Out of curiosity, I loaded up the save again, debugged in Stones' Fortitude (an Earthshaper spell from Magiclysm that reduces your metabolism, among other things), and got this:

So, just extra-confirming the above.

Probable reason: same as #72255; while the zero metabolism do not hang the game anymore, values close to zero still can cause a lot of slowdown due the loop Ren posted before.
Nota bene: should check what happens when enchantment falls below zero

Bumping this issue. I experienced this bug and being an 18 Int Snail Mutant with a Recycler CBM was enough to completely break my game/save file. That makes it a base game save-breaking bug that would tend to kick in on files that had time to establish Light Eater+Recycler. I had to edit out the Recycler CBM to continue playing. It's bad.

(Thanks to the discord server for helping me troubleshoot and esp @GuardianDll )

index 2796a2039f..70a9341a4c 100644
--- a/src/consumption.cpp
+++ b/src/consumption.cpp
@@ -715,7 +715,9 @@ float Character::metabolic_rate_base() const
 {
     static const std::string hunger_rate_string( "PLAYER_HUNGER_RATE" );
     float hunger_rate = get_option< float >( hunger_rate_string );
-    return enchantment_cache->modify_value( enchant_vals::mod::METABOLISM, hunger_rate );
+    const float final_hunger_rate = enchantment_cache->modify_value( enchant_vals::mod::METABOLISM,
+                                    hunger_rate );
+    return std::clamp( final_hunger_rate, 0.0f, float_max );
 }
 
 // TODO: Make this less chaotic to let NPC retroactive catch up work here

The basic issue is that Character::metabolic_rate_base() comes back negative so Character::weariness_level() gets stuck in the while loop constantly incrementing the amount higher and higher (because threshold is negative due to negative bmr) until it overflows to negative