Tweak hunger/health mechanics:

Ensure hunger is always ticking away, and ensure that health regen
is quicker when hunger bar is full.
And, tweak saturation to partially use up hunger to heal; instead
of healing on top of hunger.

mods/PLAYER/mcl_hunger/api.lua

@@ -33,8 +33,9 @@ if mcl_hunger.active then
 		hunger = math.min(20, math.max(0, hunger))
 		player:get_meta():set_string("mcl_hunger:hunger", tostring(hunger))
 		if update_hudbars ~= false then
-			hb.change_hudbar(player, "hunger", hunger)
+			-- math.floor(hunger) to stop the hunger float value from breaking the hud.
-			mcl_hunger.update_saturation_hud(player, nil, hunger)
+			hb.change_hudbar(player, "hunger", math.floor(hunger))
+			mcl_hunger.update_saturation_hud(player, nil, math.floor(hunger))
 		end
 		return true
 	end
@@ -68,6 +69,9 @@ if mcl_hunger.active then
 			local s = mcl_hunger.get_saturation(player)
 			if s > 0 then
 				mcl_hunger.set_saturation(player, math.max(s - 1.0, 0))
+				h = mcl_hunger.get_hunger(player)
+				h = math.max(h-0.25, 0)
+				mcl_hunger.set_hunger(player, h)
 				satuchanged = true
 			elseif s <= 0.0001 then
 				h = mcl_hunger.get_hunger(player)

mods/PLAYER/mcl_hunger/init.lua

@@ -28,6 +28,7 @@ mcl_hunger.EXHAUST_SWIM = 10 -- player movement in water
 mcl_hunger.EXHAUST_SPRINT = 100 -- sprint (per node)
 mcl_hunger.EXHAUST_DAMAGE = 100 -- taking damage (protected by armor)
 mcl_hunger.EXHAUST_REGEN = 6000 -- Regenerate 1 HP
+mcl_hunger.EXHAUST_HUNGER = 5 -- Natural hunger overtime.
 mcl_hunger.EXHAUST_LVL = 4000 -- at what exhaustion player saturation gets lowered
 
 mcl_hunger.SATURATION_INIT = 5 -- Initial saturation for new/respawning players
@@ -147,7 +148,13 @@ minetest.register_globalstep(function(dtime)
 		if food_tick_timer > 4.0 then
 			food_tick_timer = 0
 
-			if food_level >= 18 then -- slow regenration
+			-- let hunger work always
+			if player_health > 0 and player_health <= 20 then
+				mcl_hunger.exhaust(player_name, mcl_hunger.EXHAUST_HUNGER) --natural hunger overtime always ticking.
+				mcl_hunger.update_exhaustion_hud(player, mcl_hunger.get_exhaustion(player))
+			end
+
+			if food_level >= 18 and food_level < 20 then -- slow regenration
 				if player_health > 0 and player_health < 20 then
 					player:set_hp(player_health+1)
 					mcl_hunger.exhaust(player_name, mcl_hunger.EXHAUST_REGEN)
@@ -164,10 +171,10 @@ minetest.register_globalstep(function(dtime)
 				end
 			end
 
-		elseif food_tick_timer > 0.5 and food_level == 20 and food_saturation_level >= 6 then -- fast regeneration
+		elseif food_tick_timer > 0.5 and food_level == 20 or food_saturation_level > 0 then -- fast regeneration
 			if player_health > 0 and player_health < 20 then
 				food_tick_timer = 0
-				player:set_hp(player_health+1)
+				player:set_hp(player_health+1.5)
 				mcl_hunger.exhaust(player_name, mcl_hunger.EXHAUST_REGEN)
 				mcl_hunger.update_exhaustion_hud(player, mcl_hunger.get_exhaustion(player))
 			end