Not every day now, but I've done enough hard manual labor to know that it wouldn't allow me to eat 13 pounds of potatoes. Seriously no one was eating that much on as regular basis.
Once you spend every single day doing hard manual labor for years consuming potatoes for the majority of your calories then tell me 13 pounds is impossible.
Sure, its impossible for you now, but that's totally irrelevant. An equivalent statement would be "it's totally impossible for a human to throw a baseball at 90mph, I tried for a whole week once and I only threw 40mph."
If your diet is 90% potatoes and you do hard manual labor all day, you would absolutely need about 7 pounds of potatoes (2500 calories). I don’t think 13 pounds seems that crazy. I have sat down at a meal and eaten 3 pounds of potatoes before.
A Russian and American soldier meet during some peacekeeping mission/veteran fair and discuss which army is better.
They go through weapons, the American really likes AK-47. They talk about training. They discuss the distributed vs centralized command.
Finally the American says that they eat 5k calories per day. The Russian suddenly jumps up, points his finger at the American and starts yelling: "Liar! Nobody can eat that much potatoes!"
The problem is digesting that quantity of food, not the energy content. Elite athletes typically eat some potatoes but most of what they eat is more nutrient dense.
Seriously guys, get out your scale and weigh 13 pounds of potatoes. Could you really consume that much volume in a day without feeling sick? Let's do a reality check here.
About 6 weeks into a cross country bike tour, I spent a rest day eating all day. I think I ate 4 massive burgers and a large supreme pizza. Probably somewhere around 6000 calories.
A week prior, I ran out of food in the mountains. I finally got to a store, bought a loaf of bread, a pack of Oscar-Meyer bologna, a pack of cheese slices, two sodas, and a red bull. When I left the bench near the store, I had a few slices of bread left.
When you put out incredible amounts of energy, you can eat a fairly incredible amount of food. I don't understand where the food goes, it really doesn't feel like you should be able to eat that much volume but you can.
Those foods you ate are all more calorically dense than plain potatoes so my point still stands. It's not about the calories but the total volume of food that the human gut can process in a day. Have you seen 13 pounds of potatoes?
Potatoes are ~0.7kg/L, so that's ~8.4L of potato over the course of the day & 370 grams per waking hour, which is one big potato.
Yes my examples were somewhat high energy density but in the second example, I probably had 3L+ in my belly in just one meal. Honestly I think your body just gets used to it.
I'm not familiar with the 13 lb of potato claim, but it strikes me as a stretch (hah!) but not inherently implausible.
I had a HS friend who was a serious swimmer (not quite Olympic level but he won state championships) and watching him eat was insane. He would eat about 3x of what we all ate. Like literally down 3 sandwiches while we had one. I think he was on a 6000 calorie a day diet. I believe the potato thing. It sure sits outside what I think I could eat, but having seen others do similar, it seems realistic.
I do weightlifting and have gone through times where I do more weightlifting and less. The body just absorbs food when you do more work. Can't tell you the mechanics but it's way easier for me to digest more food when I do more weightlifting.
