There are a couple experiences that have made me think of this question.

One happened in the fall. As I walked around a neighborhood near where I lived, I noticed large mossy spheres that seemed to be growing on all the rose bushes I passed. Eventually, I came to a bush that wasn't on anyone's property and crushed one of the mossy spheres in my hand. I couldn't see anything in particular, but I suspected it was the doing of some insect. I realized there were blackened versions of the galls hanging from the bushes, too, and crushed some of those. I only crushed a few, and found little dead flies inside a couple of them. My guess is that those rose gall wasps never made it out of the spaces they chewed for themselves as larvae and starved to death inside of the dark rooms.

Another was when I noticed small dark lines on my shower's grooved floor. I was immediately worried it was some kind of living thing, and when I squatted down to get a better look, my fears were confirmed. They were slowly moving around the floor of the shower. It made me ashamed that I had seen drain flies and not thought sooner to kill them to prevent this situation. Now, I had larvae that were hard to crush, who I could let dry out and starve, or flush down the drain. I flushed them down and started covering my shower drain with an upside-down peanut butter jar lid. Every day, I check the lid for flies and crush them after moving the lid into a Ziploc baggie. I'm not sure if it was the change in weather or this technique, but I haven't seen any in a few days.

The other time was when I heard a talk about the effects of fasting from a professor that eats one meal a day. (He was not trying to convince the audience of changing their eating habbits, but rather describing efforts to create the effects of fasting without having patients fast.) Afterwards, I had to know, were people who fasted... hungry? I asked a couple friends who said that, no, they were not hungry after a couple weeks of starting a different meal schedule. It was hard for me to believe, but it reminded me of a few other people I'd met who said they weren't hungry and only had a couple small meals a day. 

When I started reading accounts of famines, I was surprised to learn about the effects of acute hunger. These were horrific experiences that became all-consuming. This was obvious not only from their descriptions of their internal experiences, but also the remarkable behavior that hunger motivated. Here are some excerpts from non-fiction books and videos that I found, mostly mentioned in this forum post. I wanted to include a more recent famine, and I was disappointed to find that there is not much written about famines in Madagascar or Ethiopia, even though they are recurring, brutal, and climate change-related.

Hungry Ghosts: Mao's Secret Famine by Jasper Becker - A history of China from 1958-62

Living on the verge of death produced a strange state of mind, as Han Weitian recalls: 

In those years, starvation became a sort of mental manacle, depriving us of our freedom to think. We could not for a moment forget its threat. It seemed to be continuously putrefying the air and making it difficult to breathe... it is strange that hunger can cause so much pain in your body. It seems like a vice pinching all your bones which feel dislocated for lack of flesh and sinews. Your head, hands, feet, even your belly and bowels are no longer where they normally are. You are tempted to cry out loud but haven’t the strength. When experiencing extreme hunger, one can barely utter an audible sound.

During the famine of the Great Leap Forward, peasants killed and ate their children in many parts of China. In Wild Swans, Jung Chang recounts the story told by a senior Party official about an incident in Sichuan: ’One day a peasant burst into his room and threw himself on the floor, screaming that he had committed a terrible crime and begging to be punished. Eventually it came out that he had killed his own baby and eaten it. Hunger had been like an uncontrollable force driving him to take up the knife. With tears rolling down his cheeks, the official ordered the peasant to be arrested. Later he was shot as a warning to baby killers.

Far to the north in Shenyang, Chi An made pancakes out of leaves picked from the poplars which lined the streets. The leaves were soaked overnight to remove tannic acid, then dipped in flour and browned in a wok without oil. 'The smell of these leaf pancakes frying made my mouth water, but they didn’t taste nearly as good as they looked. Despite the soaking, the poplar leaves retained an acid bite that made my salivary glands scream in protest. The worst part was the constipation they brought on. A day after Mother added them to our diet, we stopped having bowel movements. For a week after that, we felt increasingly bloated and crampy. Finally mother told us we would have to dig the hard little balls of faeces out with our fingers. My brother and I were too hungry to mind very much, though; we continued to devour the pancakes without protest.'

Nothing to Envy by Barbara Demick - A history of North Korea in the 1990's

So they began their grim new regimen, quite a fall from grace for a couple who had fancied themselves gourmets. Mrs. Song would hike north and west from the city center to where the landscape hadn’t yet been paved, carrying a kitchen knife and a basket to collect edible weeds and grass. If you got out to the mountains, you could maybe find dandelion or other weeds so tasty that people ate them even in good times. Occasionally, Mrs. Song would find rotten cabbage leaves that had been discarded by a farmer. She would take the day’s pickings home and mix it with whatever food she had enough money to buy. Usually, it was ground cornmeal—the cheap kind made from the husks and cobs. If she couldn’t afford that, she would buy a still cheaper powder made out of the ground inner bark of the pine, sometimes extended with a little sawdust. No talent in the kitchen could disguise the god-awful taste. She had to pound away and chop endlessly to get the grasses and the barks into a soft-enough pulp to be digestible. They didn’t have enough substance to be molded into a recognizable shape like a noodle or cake that might fool a person into thinking he was eating real food. All she could make was a porridge that was flavorless and textureless. The only seasoning she had was salt. A little garlic or red pepper might have disguised the terrible taste of the food, but they were too expensive. Oils were unavailable at any price and their complete absence made cooking difficult. Once while visiting her sister’s sister-in-law for lunch, Mrs. Song was served a porridge made out of bean and corn stalks. Hungry as she was, she couldn’t swallow it. The stalks were bitter and dry, and stuck in her throat like the twigs of a bird’s nest. She gagged, turned beet red, and spat it out. She was mortified. In the year after Kim Il-sung’s death the only animal product she consumed was frog. Her brothers had caught some in the countryside. Mrs. Song’s sister-in-law stir-fried the frogs in soy sauce, chopped them into small pieces, and served them over noodles. Mrs. Song pronounced it delicious. Frog wasn’t typically part of Korean cuisine; Mrs. Song had never tried it before. Unfortunately, it would be her last opportunity. By 1995, virtually the entire frog population of North Korea had been wiped out by overhunting. By the middle of 1995, Mrs. Song and her husband had sold most of their valuable possessions for food. After the television went the used Japanese bicycle that was their main means of transportation, and then the sewing machine with which Mrs. Song had made their clothes. Chang-bo’s watch was gone, as was an Oriental painting given to them as a wedding present. They sold most of their clothes and then the wooden wardrobe in which they stored them.

The famine not only put prostitution back onto the street, it brought out a new class of prostitute—often young married women desperate to get food for their children. They often asked for nothing more than a bag of noodles or a few sweet potatoes as payment.

There was also suddenly white rice, lots of it, in big 40-kilo burlap sacks imprinted with Roman letters (UN, WFP, EU) and the interlocking olive branches of the United Nations symbol and the U.S. flag, which every North Korean recognized from the propaganda posters where it was invariably shown dripping with blood or pierced with bayonets. Why was there rice in sacks with the flag of North Korea’s most dreaded enemy? Somebody told Mrs. Song that the North Korean army had captured rice from the American warmongers. One day Mrs. Song spotted a convoy of trucks driving away from the port with similar burlap sacks stacked in the back. Although the trucks had civilian license plates, Mrs. Song knew they had to belong to the military—nobody else had gasoline—and she finally figured out that this was humanitarian aid that somebody in the military was selling for profit at the market. No matter where it was from, people in Chongjin were happy to see white rice, which hadn’t been available at the public distribution center for years.

There was nothing about the boy to distinguish him from hundreds of other children hanging around the train station. North Koreans called them kochebi, “wandering swallows”—children whose parents had died or gone off to find food. Left to fend for themselves, they tended to flock like pigeons scavenging for crumbs at the train station. They were a strange migratory phenomenon in a country that previously had never heard of homelessness.

Kim Hyuck was tiny, but strong and wily. If you bought a snack to eat at the station, he could snatch it from your hand before it reached your mouth and swallow it in a single gulp. Vendors covered buckets of food with tightly woven nets to keep out sticky fingers, but at the precise moment that the net was lifted, he could topple the bucket and grab something from the pavement. These were skills acquired at an early age and perfected over the course of a childhood marked by food deprivation. Without them, he wouldn’t have survived for very long. 
[...] The first time Hyuck stole from a stranger he was ten years old. He took a sticky rice cake with red bean filling from a vendor’s cart and ran for it. His little legs pumped faster than the vendor’s and he should have gotten away with it. His undoing was that the rice cake was so sweet and delicious that he came back for a second helping. Hyuck’s father picked him up at the police station. Hyuck kept his head bowed in shame as the tears welled in his eyes. At home, his father whipped him with a leather belt, raising red welts on his calves. “No boy of mine will be a thief,” his father raged. “Better to starve than to steal.”
[...] But by winter, their rations were cut. Instead of rice, the children got corn noodles floating in a bowl of salted soup. In the first three months of 1996, twenty-seven children died at the orphanage. Hyuck and his brother cut classes and walked to town to look for food. They discovered the situation wasn’t much better there. Hyuck met a boy his own age who was living with his six-year-old sister because their parents had died. Neighbors came in periodically with bowls of porridge, but otherwise the children were fending for themselves. Hyuck and his brother, along with their new friend, went out together to forage for food. Hyuck was a good climber, with long, muscular arms that compensated for his short, stubby legs. He could scale pine trees and with a sharp knife peel away the outer bark to get to the tender bark underneath. It was yellow, chewy, and sweet, and sometimes he would eat it while clinging to the tree. Others were trying to do the same, but Hyuck could get higher, where the bark was untouched. “You’re a little monkey,” his friend told him with admiration. Hyuck became a hunter. He killed rats, mice, and frogs and tadpoles. When the frogs disappeared, he went for grasshoppers and cicadas. As a small boy in Chongjin, he used to watch his friends catch and eat cicadas at the Sunam River, but he’d always found it disgusting. Now he was not so fussy. He took some netting and devised traps for sparrows, dangling a kernel of corn on a string as bait. They plucked the birds’ feathers and barbecued them on a spit. He also tried to catch pigeons with a basin and string, but discovered the pigeons were too smart. Not so the dogs. Hyuck found a small and friendly stray, wagging its tail as it followed him into his friend’s yard. Hyuck shut the gate behind them. He and his friend grabbed the animal and shoved it into a bucket of water, holding down the lid. The drowning dog struggled for ten minutes before dying. They skinned it and barbecued it. Dog meat was part of the traditional Korean diet, but Hyuck liked animals and felt bad, though not so bad that he didn’t try it again—although by mid-1996 dogs too were scarce. Hyuck continued to steal. He and his brother climbed walls and dug up clay kimchi pots that had been buried in private gardens. They shoveled the kimchi straight out of the pots into their mouths. All the while, Hyuck remembered his father’s admonition: “It’s better to starve than to steal.” In the imaginary dialogue that Hyuck kept up with his father, he retorted, “You’re no hero if you’re dead.”

Few of the children had shoes. If they did, they would soon swap them for food and instead use plastic bags to cover their feet. They often suffered frostbite. […] When begging failed, the children picked up anything on the ground that was vaguely edible. If they couldn’t find food, they would pick up cigarette butts and reroll whatever tobacco remained with discarded paper. Almost all the children smoked to dampen their hunger.

Supposedly, one father went so insane with hunger that he ate his own baby. A market woman was said to have been arrested for selling soup made from human bones. From my interviews with defectors, it does appear that there were at least two cases—one in Chongjin and the other in Sinuiju—in which people were arrested and executed for cannibalism. It does not seem, though, that the practice was widespread or even occurred to the degree that was chronicled in China during the 1958-62 famine, which killed as many as 30 million people.

Night by Elie Weisel - A memoir of a Holocaust survivor

Occasionally, we would pass through German towns. Usually, very early in the morning. German laborers were going to work. They would stop and look at us without surprise. One day when we had come to a stop, a worker took a piece of bread out of his bag and threw it into a wagon. There was a stampede. Dozens of starving men fought desperately over a few crumbs. […] In the wagon where the bread had landed, a battle had ensued. Men were hurling themselves against each other, trampling, tearing at and mauling each other. Beasts of prey unleashed, animal hate in their eyes. An extraordinary vitality possessed them, sharpening their teeth and nails. A crowd of workmen and curious passersby had formed all along the train. They had undoubtedly never seen a train with this kind of cargo. Soon, pieces of bread were falling into the wagons from all sides. And the spectators observed these emaciated creatures ready to kill for a crust of bread. A piece fell into our wagon. I decided not to move. Anyway, I knew that I would not be strong enough to fight off dozens of violent men! I saw, not far from me, an old man dragging himself on all fours. He had just detached himself from the struggling mob. He was holding one hand to his heart. At first I thought he had received a blow to his chest. Then I understood: he was hiding a piece of bread under his shirt. With lightning speed he pulled it out and put it to his mouth. His eyes lit up, a smile, like a grimace, illuminated his ashen face. And was immediately extinguished. A shadow had lain down beside him. And this shadow threw itself over him. Stunned by the blows, the old man was crying: “Meir, my little Meir! Don't you recognize me…You're killing your father… I have bread…for you too… for you too…” He collapsed. But his fist was still clutching a small crust. He wanted to raise it to his mouth. But the other threw himself on him. The old man mumbled something, groaned, and died. Nobody cared. His son searched him, took the crust of bread, and began to devour it. He didn't get far. Two men had been watching him. They jumped him. Others joined in. When they withdrew, there were two dead bodies next to me, the father and the son.

Madagascar 2021-2022

From this news clip:

I rely on God. Today we have absolutely nothing to eat except cactus leaves that we are trying to clean up. We have nothing left. Their mother is dead and my husband is dead. What do you want me to say? Our life is about looking for cactus leaves again and again to survive.

From this video:

For maybe two years we haven’t harvested anything. We’ve had to feed ourselves by digging for roots. Since it last rained, the locusts have hatched. That saved us. Without the locusts, we’d all be dead. […] The Dahalo came from the north to steal our cattle. They whistled their signal and then began shooting. We fled into the forest. They kept coming back. First they stole our cattle, then our goats and our pots and pans. Now when they come, we quickly gather our locusts, and run into the forest.

The bandits block the road when someone is transporting food. They take everything, leaving people empty-handed. So you can’t bring food back to the villagers. People just eat their millet in the town, instead of bringing it here to share. Then the bandits make their getaway.

When I grow up, I want to find work so that I can support my parents. And I have this to say to the president: Please let us have our house, and buy us pots, pans, plates, and spoons. A house would be amazing. And I really want to go to school.

Concluding remarks

Before researching this topic, I usually thought of extreme suffering as occurring for short periods of time. Yet, many people in these examples went years with intense hunger and survived. Acute hunger often takes precedence over everything else, as illustrated by firsthand accounts of the experience and the extreme actions it can lead to.