Some people find my eating habits to be quite unusual; I tend to not eat until I'm very low on hunger, as little as one drumstick (2 hunger), which is often seen as a major disadvantage because you can no longer sprint (3), much less heal (9), but the fact is I don't sprint much, which isn't easy to do in most caves (I mostly sprint when going to/from where I've been caving and my current base), and don't take much damage, and being down by a heart of two isn't that concerning, and when I do get in a big battle the slow regeneration in 1.6.4 (no saturation boost, only the half a heart every 4 seconds that you get without saturation in 1.9+) isn't going to make much of a difference in most cases. In part as a reply to another thread (getting a bit off-topic) I decided to track my eating while playing today.
This is the game output; I ate a total of 15 times over about 3 hours with the time of each screenshot corresponding to when I ate, except for the last time:
This is a screenshot of the "session stats" shown in the game output; the session itself was more or less average, perhaps a bit shorter than usual, yet with more ores mined as I've been exploring a region of higher cave/mineshaft density and spent less time on searching for new areas to explore as a result:
The first time I ate after a depleting a full hunger bar from the previous session; this also shows that I started with 56 baked potatoes, ending at 33, or 23 consumed. Note that I technically eat twice when getting this low, first a single baked potato, then two more a minute or two later (3 baked potatoes have 21.6 saturation so eating 3 at once will lose 1.6 saturation since it can't exceed 20; yes, I'm that picky about wasting food). Sometimes I'll even not eat again until the hunger from the first potato has been depleted; on occasion I've also caught myself starving, all because I haven't lost much health:
Next I ate a piece of bread that I found in a dungeon; in this case I ate when I was down by the same amount of hunger as bread restores:
In this case I decided to eat after dropping down to 4 drumsticks (2 baked potatoes to restore full hunger) as I'd been fighting a fair number of mobs recently, and made a "stop" anyway to craft more torches:
Another case of dropping down to a single drumstick:
I'd just defeated a wave of zombies that came from a dungeon, with a bit more health lost as a result (in general, I avoid eating unless I am down by exactly the amount that can be restored by whatever food I have, or 6/12/18 for baked potatoes):
One of the zombies dropped a carrot, which I ate along with bread from the dungeon (this includes crafting multiples of 3 wheat into bread; I leave any wheat left over in the chest):
This is the second piece of bread that I had earlier (I also ate a baked potato previously as bread would have only brought me up to 17 hunger):
The next three times I ate were all from 1 drumstick left:
The biggest threat I experienced over the session was a large group of skeletons from a dungeon, including one with an enchanted bow, perhaps even Power III; you can see that I blocked myself off so I could eat and heal (it doesn't have to be complete, no mobs other than cave spiders could get in through the opening). This is also the only time I "overate", losing 2 hunger from the 12 that 2 baked potatoes restore:
I then ate a single baked potato after dealing with a cave spider spawner, which took off 3 hearts; if I'd been full enough to heal I would have only regenerated one heart during the time it took to kill them and break the spawner, which is why I mentioned it doesn't make much of a difference in many cases (poison also acts slowly, including from witches, so if necessary I can block myself off before my health becomes dangerously low):
Everything I ate after this was bread that I found in a mineshaft, a good example of how I can subsist entirely off of bread taken from minecarts and dungeons (unsurprisingly, the amount of bread and wheat they have was nerfed in later versions); note that I'm eating up to 3 pieces of bread at a time, enough to restore full hunger from 5 hunger left (i.e. I prefer to eat bread when down by 5/10/15 hunger):
In all, I ate 23 baked potatoes, 11 bread, and one carrot for a total of 433.4 hunger and saturation consumed, or the equivalent of 33 baked potatoes if they were all I ate (note that in 1.6.4 baked potatoes restore 6 hunger and 7.2 saturation and carrots restore 4 hunger and 4.8 saturation, which were reduced in 1.8), so a single stack of baked potatoes is plenty to last me through more than two 3+ hour long play sessions with a very active playstyle, with inventory/ender chest space or wood almost always being the limiting factor, not food (even if I do not find a mineshaft I still find several dungeons and zombie drops; if they drop a potato I'll cook it the next time I set up furnaces to smelt iron and gold).
Also, I analyzed how much hunger I spent in total over the lifetime of a world and what cost the most hunger; this was a modded world with more and harder mobs which contributed to a slightly higher amount of hunger used per play session (equivalent of 38.5 baked potatoes, compared to 33 for today's session in my first world, which is "semi-vanilla"; mob spawning is vanilla except cave spiders and witches naturally spawn at a similar rate as in 1.7 and mob spawners have half the maximum delay):
Jumping (assumes 10% are sprint-jumps): 47054 (3565 baked potatoes)
Regeneration (after 76.16% damage reduction from armor): 33977 (2574 baked potatoes)
Walking (assumes 90% walking/10% sprinting): 24190 (1833 baked potatoes)
Attacking: 11985 (908 baked potatoes)
Mining (pickaxes only): 6456 (489 baked potatoes)
Total hunger used: 123662 (9368 baked potatoes; I crafted 10818 with multiple stacks at 3 bases so this is pretty close when including minor sources of hunger loss like swimming)
Hunger per play session: 508.9 (38.5 baked potatoes)
It reminds me how picky i am about using coal for fuel when the item in question doesn't equal 8.
In that case i use sticks, sapplings or whool.
I do the same thing, along with making sure that the amount I'm smelting evenly goes into blocks with no leftovers (e.g. 9 stacks of iron ore = 1 stack of iron blocks), as this saves up to 2 slots and maximizing inventory (ender chest) space is important to me as this is usually the limiting factor as far as how long I can go.
Also, when repairing my gear I use the sacrificial items until an optimal repair can be made, where the sum of the item durabilities plus the 12% bonus the anvil gives adds up to 100% (within a few points), even if this means using inferior items (I always get Efficiency I on pickaxes as even this does mine noticeably faster; if they only get Unbreaking (from a level 1 enchant) I'll enchant books until I get Efficiency. In the case of armor I'll wear helmets I save from mob drops to offset the loss of Protection). The exceptions are my sword, which I wear down by killing chickens, which is necessary due to the full durability sacrifice cost being over the anvil limit (otherwise, I'd have to use individual diamonds to repair my sword; all other items can be repaired with an intact sacrifice), shears, which must have Silk Touch in order to collect cobwebs, and bow, which I repair with bows dropped by skeletons (combined to around 80-90% durability). All other items come from trading so I'm not doing this to save on mined resources, nor do I need to conserve XP.
When out and about exploring, a Looting3/FireAspect2 sword reigns supreme. Any encountered pig/chicken/cow/sheep/hoglin is 2-4 instant meals.
When caving, or generally any activity where I might take damage, I keep my food bar topped off. Even with fully enchanted netherite gear. Better safe than sorry.
I used to be economical about my smelting too. But in my current 1.18 world, once I set up a lava farm next to my smelter, I no longer care. Whether I am smelting 5 items or 500, I just use lava buckets.