Well... yes and no. 5000 calories is a lot, even in high-caloric foods. I think you would poop a lot and you wouldn't WANT to eat that much food because you wouldn't need to. The calorie argument is a red herring - it is a piece of information, but only a small one.
But I can tell you this. After eating high-fat (animal fats, butter, coconut oil, olive oil), no grains/legumes and virtually no sugar for a year, and not counting calories at all or exercising any more than I normally did, I lost 15 lbs and 2 inches off my waist. Actually that happened in the first 3 months, but I tracked it for a year. I went from 170 lbs to 155. If I were overweight, I would have lost a lot more. I have been eating this way for 4 years now, and after increasing my non-grain carbs a little I am at 160 with no effort. And I feel better than I ever have. There are other great effects of eating this way, such as reducing inflammation.
A year or so ago I did track what I ate and measured the fat/calories/sugar for a week. It was typical, and I made no adjustments to my diet.
The daily average came out to 2300 calories, 54 grams carbs, 186 grams fat, 18 grams sugar. I actually expected the calories to be higher, but that is what I found. I did actually think for a moment "oh no, I'm not eating enough... the average male should consume..." NO! That is generalized hogwash for the masses based on old information (I can't even call it science). Watch this video by Dr Peter Attia on Vimeo who talks about how our Dietary Guidelines are what they are. I know.. it's long, but it's really interesting. He has some really deep info on his website about how our diet and fat affects our cholesterol. Another fun fact - high cholesterol isn't bad. Another fun fact - half of all people who have heart attacks have normal cholesterol. Cholesterol is simply one thing, one factor in the grand scheme... but you know what doctors say... you need to lower it, I want you to take statins. (which are at the top of the most prescribed drug lists, in quantity and in dollars) But I digress...
I think it would be hard to eat 5000 calories in a day. I can see where someone doing vigorous work all day would require more food, but that is not saying the same thing as "just eat fewer calories and you will lose weight". I can only explain so much... I referenced some good books that go into far greater detail on the topic. Your body operates on hormones, and what you eat directly impacts that process. Calories do not. It's really that simple. But please, don't take my word for it, find those books and read them. The information is out there.