Judging from this guy, I'd say 69 hot dogs or 103 hamburgers.

http://en.wikipedia.org/wiki/Joey_Chestnut

But I think you'll agree, that ain't healthy...

As you can imagine, it really varies on the person. I'd say if you aren't feeling overstuffed/suffering pain (either going down or coming out), don't worry about it. Just keep an eye on your weight and the like and see how things go.

The limits are how often you wish to eat and how much food you can metabolize while meeting your weight goals--to increase, decrease or maintain.

I'm in weight loss mode. I plan a large meal and a small meal but I plan carefully and I've finally learned to eat very slowly so there's no undue stress on my innards. After my main meal, which I usually have in the afternoon, I IF until the next day.

My small meal is a cup of full-fat yogurt with fruit. I enjoy this in mid-morning while I sip coffee.

For the main meal, I like to start with chunks of leaf lettuce, celery and cuke--nice volume, not much density but takes the edge off very nicely and I happen to really like oil & vinegar.

Next, I have a main course with low-temp-fried bacon, using the fat to slowly cook some beef and finishing by dumping a bone broth stew into the skillet to reheat. The bacon makes a dandy appetizer while I cook the rest.

Does it feel too hard on the digestion? That's the ultimate judge, but I think you'd struggle to eat so much in a single meal that it caused serious problems. You might fancy a nap after your kill though...

If you want to experiment, you can count calories and get a general feel for what amount makes you feel "stuffed." I find that my upper limit is about 1700 calories (combining meat and starch) - where continued eating would be physically uncomfortable. At that volume, I can feel more digestion happening than usual but other than that there are no negative effects.

*note that this was done in the context of eating after a 30 min session of HEAVY weightlifting following the general guidance of the Leangains protocol.

A lot of recent research is implicating postprandial lipids with metabolic disorders, and specifically triglyceride clearance rates seem to correlate highly with metabolic syndrome and such.

Also, like that recent study someone posted here about with caffeine, fat and glucose clearance, the "large fat meals" used generally exceed 50g fat.

As someone who has processed more blood samples than I care to recall, it's easy to identify which samples came from someone who recently ate a high fat meal.

Personally, if I were lean and needed to be a big eater, I think I'd err on the side of caution and space out meals a bit.

For all the bluster about insulin and locking fat in your fat cells, a healthy person does just that in appropriate fashion. You WANT your dietary fat efficiently stored away in your fat cells until it's needed.

I am a woman of small stature and size and I eat a pound and a half of meat for breakfast. And another pound or two at lunch. What's wrong with that? It feels awesome!!

I connect it with activity. When I eat a meal like you describe, I figure on a ten mile hike to burn it up. If you're young and big you might get by with half of that.

I find that the upper limit is highly reward-dependent.

Earlier this year I was managing to sometimes eat 1kg of beef in a given "meal". (I would cook it up in three portions because my pan isn't big enough to cook 1kg and so there would be some waiting between the portions though.) This corresponds to about 2000 calories. I would also add in about 6 slices of cheese and ample tomato sauce. If there was a bag of chips lying around that I had willed to be forbidden until eating real food, I could manage it. So in the space of a couple hours I would have consumed >3000 calories.

Then I decided to try to reduce my cheese consumption since it was highly-processed cheddar slices I was using. I reduced the beef to cheese ratio by about half, which made the meal less rewarding but I figured I would get used to it. I also started replacing tomato sauce with olive oil.

But then my appetite for my standard beef meal went down substantially. I'm pretty sure it was just that the meal wasn't terribly interesting. Since before I was able to manage 1kg at a time, and because I'm trying to gain a little more weight, I would try to eat more beef than felt right at the time. But that just made me feel sick. And yet I could still manage to add in additional chips if I wanted afterwards without these consequences. I've started increasing the amount of cheese I have with my beef again.

(TL;DR) So my n=1 experience suggests food reward is highly psychosomatic and can influence your appetite substantially, possibly to the extent of making the difference between feeling sick or fine after eating a certain amount. If your food is rewarding, your body will open all the doors and find room for a lot of it. If it's very bland, the upper limit may be much lower.

Your body can only synthesize about 30 grams of protein in one sitting, so you should shoot for about that much. The "eyeball test" states lean meat portions should be no larger than the size of your palm; fattier meats should be smaller. I'd keep my meals under about 500 calories (3 meals and two snacks), as anything much more than that is just going to be turned into fat.