Why Am I So Hungry? The Science and Psychology of Hunger
Why am I so hungry? It is one of the most-Googled questions about eating, and almost every answer you will find is a polite way of saying you are not. You are bored, thirsty, tired, or just not disciplined enough. This episode is about where that interrogation came from and why most of it is nonsense. Hunger is not one thing. It is three or four separate biological systems wearing a single word, and the cultural reflex to distrust all of them runs about 800 years deep. We trace it from medieval fasting saints, through a wildly influential 1960s experiment that turned out to be junk science, to the new research on ghrelin, leptin, AGRP neurons, ultra-processed food, and GLP-1 drugs that almost nobody is talking about. The short version: your body usually knows what it is talking about.
- 00:00Cold open: hunger is a trick question
- 02:07What is hunger, and why is it so loaded
- 04:54Culture cannot pick a lane: ignore it, override it, obey it, delete it
- 08:11Defining hunger: ghrelin, hedonic, habitual, and the separate satiety system
- 11:53A short, weird history of distrusting hunger: saints, Sylvester Graham, Lulu Hunt Peters
- 14:05Stanley Schachter and the externality hypothesis
- 17:35The science fell apart but the belief stuck
- 20:18The Minnesota Starvation Experiment
- 25:46Leptin, 1994, and the off switch that wasn't
- 28:03The new science: AGRP neurons and anticipatory hunger
- 31:53Kevin Hall, the metabolic ward, and ultra-processed food
- 36:30GLP-1 drugs, the brain, and food noise
- 38:41What this means for how we think about hunger
- 40:38Why some people run hungrier: genetics, sleep, stress, the menstrual cycle, aging, RED-S
- 46:40The willpower myth: ego depletion and the replication crisis
- 53:13What hunger cues actually feel like, and the limits of "just listen to your body"
- What hunger actually is
- Homeostatic vs. hedonic hunger
- Ghrelin and leptin
- Satiety hormones (CCK, PYY, GLP-1)
- Habitual and cued hunger
- The history of distrusting hunger
- The externality hypothesis
- The Minnesota Starvation Experiment
- Why finding leptin didn't fix hunger
- AGRP neurons and anticipatory hunger
- Ultra-processed food and appetite
- GLP-1 drugs and food noise
- Genetics of hunger (FTO, MC4R)
- Sleep, stress, and appetite
- Hunger and the menstrual cycle
- Hunger, athletes, and RED-S
- Willpower and ego depletion
- The limits of intuitive eating
- Baumeister, R. F., Bratslavsky, E., Muraven, M., & Tice, D. M. (1998). Ego depletion: Is the active self a limited resource? Journal of Personality and Social Psychology, 74(5), 1252–1265.
- Betley, J. N., Xu, S., Cao, Z. F. H., Gong, R., Magnus, C. J., Yu, Y., & Sternson, S. M. (2015). Neurons for hunger and thirst transmit a negative-valence teaching signal. Nature, 521(7551), 180–185.
- Bynum, C. W. (1987). Holy Feast and Holy Fast: The Religious Significance of Food to Medieval Women. University of California Press.
- Drucker, D. J. (2018). Mechanisms of action and therapeutic application of glucagon-like peptide-1. Cell Metabolism, 27(4), 740–756.
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- Hall, K. D., Ayuketah, A., Brychta, R., et al. (2019). Ultra-processed diets cause excess calorie intake and weight gain: An inpatient randomized controlled trial of ad libitum food intake. Cell Metabolism, 30(1), 67–77.
- Keys, A., Brožek, J., Henschel, A., Mickelsen, O., & Taylor, H. L. (1950). The Biology of Human Starvation. University of Minnesota Press.
- Schachter, S. (1968). Obesity and eating. Science, 161(3843), 751–756.
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Cold open: hunger is a trick question
Zoë: Welcome to Your Diet Sucks, the podcast that's not going to tell you to drink a glass of water to see if the feeling passes. I'm Zoë Rom.
Kylee: And I'm Kylee Van Horn. Zoë, today we're talking about hunger, which on paper sounds like a pretty basic thing. Hunger and fullness, right? You get hungry and then you have food, and it's like, how are we going to do an entire episode on this? But it starts to get confusing for people because of data and too much tracking and too many numbers and all of that.
Zoë: Right. This thing of, well, my stomach is growling but my Oura ring says I'm not hungry. My fitness app says I've eaten my calories for the day, and it's like, well, what does my fitness app know? This is one of the most misunderstood ideas we've talked about. As a woman raised in diet culture, I was explicitly told to drown out and mistrust hunger. That it's not real, that it's your brain lying to you, that willpower is stronger than hunger. This is one where, more than almost any other topic I've researched, I had the most wrong ideas. Usually going into an episode I know what I think and where culture gets it wrong. This was a checklist of messed-up stuff I have straight up believed over the course of my life.
Kylee: It tends to be one of the more challenging things for people to think about.
Zoë: If you had asked me ten days ago what hunger is, I couldn't have told you. But I could have told you 150 ways to tamp down on it, eliminate it, mistrust it, and disbelieve it.
Kylee: And people on diets are told to drink more water so they don't even listen to their cues.
Zoë: Oh yeah. Done that.
Kylee: A lot of athletes wear it like a badge of honor, too. And a lot of people in the thick of an eating disorder thrive on this idea of, I'm hungry and I'm just not going to eat. It becomes a badge of honor.
Zoë: Hunger, what it is from a physiological and psychological point of view, is all of these things. It's not just your stomach growling. It's a big, complicated feeling that straddles the brain, the body, and culture, and I didn't know what it was. That lack of understanding on my part let people with potentially even less information fill in those gaps for me. That's where eating disorders fill in the gaps. Where diet culture, data tracking, and devices fill in the gaps.
Kylee: As a dietitian, a lot of people come to me wanting permission to ignore their hunger. Like, that's a good thing, right?
Zoë: We hear it on podcasts. People set it up like it's a trick question. What if I think I've eaten enough but then before bed I'm hungry? And they look at you expecting you to say, yeah, absolutely, go to bed hungry. That is typically not the answer.
Kylee: Or they say it has to be dehydration. They've been told that, so they assume it's dehydration.
Zoë: They'll go through all of these reasons they might be hungry, and at the bottom of that list is: I need to eat more food. It's wild. Almost everyone listening has spent a big chunk of their lives in some mediated relationship with hunger. Mediated by diet culture, apps, the Instagram person, intermittent fasting, your high school health teacher, your mom, people telling you your eating is emotional. And maybe there are a few unicorns out there just being hungry and then eating like a golden retriever or an actual baby. What I find fascinating is how culturally contradictory the messaging is. Diet culture says ignore it. Fasting says override it. Intuitive eating says you must obey it. GLP-1s let you essentially delete it. Wellness culture says it's good for you, queen, obey it, unless you have too much of it, in which case don't be so disgusting. Bro science says it's bad for you. So pick a lane, culture.
Kylee: And that's where people get big feelings, right?
Zoë: So today I want us to try to answer some questions that are shockingly hard to approach. What is hunger? Is it one thing or several things? Why do we have such enormous, weird, squishy, nearly religious opinions about it? When can you trust it, and when can't you, especially as an active person? And how did we get to a point where we have a multibillion-dollar drug class whose entire purpose is to make this feeling go away?
Kylee: I'm curious. Clients come to me expecting me to agree with them about ignoring their hunger. From your perspective as a journalist, what are you coming in with?
Zoë: Every time I cover this stuff, I get so many emails and DMs from listeners going, yeah, yeah, but how do I know if I'm really hungry? As if I'm some kind of hunger doula who can help them midwife their appetite into existence. I want to put my own relationship to this on the table, because like I said, I have gotten a lot of it wrong, and I think that enhances the story rather than diminishing it. As a teenager and young adult deep in diet culture and then disordered eating, I trained myself out of being able to feel hunger. That was the whole goal initially. If I didn't feel hungry, that meant I was winning. Then in recovery, I got really into intuitive eating in a way that now I think I might have overshot. The reason I fell into an eating disorder was that I was looking for an easy solution to big life problems and a way of being in a world that makes it hard to be a person. Intuitive eating offered some of the same things. Always listen to your hunger was helpful training wheels early in recovery. Where I've landed years later wants to take some of the tools of intuitive eating but also take a harder look at the science, psychology, and physiology, because as an athlete there are ways intuitive eating has failed me and others. We'll do a whole episode on intuitive eating. We're not going to litigate that whole can of worms here. The question of "are you hungry, or are you just bored, sad, thirsty, tired" is such a diet-culture script, because it frames the default assumption as: your hunger is probably wrong, and you should check it against 900 other explanations before you even ask whether you've eaten what you need today.
Kylee: The training for dietitians is very weight-loss focused. I remember being taught that one of the questions to ask a client is whether they have a problem with emotional eating, to make sure they're actually hungry. Now, if somebody feels like they can't control themselves around food, stopping to check in can be an important step. But doing this every time you feel a hunger pang is a little wild.
Zoë: The assumption I was raised in is: no, you're not hungry, that's never the actual answer. You're bored, you need water, obviously you've had enough to eat today. You're a woman on planet Earth, all you ever do is eat. Are you hungry, angry, lonely, tired?
What hunger actually is
Kylee: So I want to define what hunger actually is, physiologically.
Zoë: If you'd asked me before doing research, I'd have given you a shrug emoji. The frustrating but honest answer is that it's three or four different biological processes that we use a single word for, which is part of why this gets so confusing. The main flavors: homeostatic hunger, your body literally needing energy, primarily driven by ghrelin, which spikes when your stomach is empty.
Kylee: Ghrelin always makes me think of a monster.
Zoë: The ghrelin gremlin. And the leptin leprechaun. That's where my brain goes. There's also the ability to sense fuel in the hypothalamus, the "I haven't eaten in six hours and I can feel it" feeling.
Kylee: But it might not be six hours, either.
Zoë: It could be 20 minutes, honestly. You can't chew on a podcast, so I always have to have a little high-protein snack before our marathon recording sessions. There's also hedonic hunger, wanting food for pleasure, not driven by energy. Primarily driven by dopamine, opioid systems, and reward circuits. This is the "I just had dinner but I want dessert" or "that smells incredible and now I want it." And when people hear dopamine and opioid systems they panic and think they're addicted. No. It is good that our brains evolved to keep us alive. If pleasure is the only reason you're eating, that's a problem. But if you hear this and think you need to kill the part of your brain that experiences pleasure, that is also a problem. Then there's habitual or cued hunger, more like classical conditioning. You've eaten lunch at noon for 30 years, so your body starts the hunger cascade at 11:45 whether or not you physically need food. Pavlov's dog: the bell rings, the dog salivates, it's lunchtime. Then satiety is a totally separate system. Leptin, CCK, PYY, and good old GLP-1. The brakes are not the same as the gas. So when someone says, I don't know if I'm really hungry, there is a real physiological reason it's confusing, beyond the diet-culture nonsense. It can be useful to ask which one you're trying to detect, because they feel different, fire at different times, and respond to different stimuli. The killer fact for me: this entire system involves dozens of hormones, multiple brain regions, gut-brain signaling, and feedback loops we are still discovering. We recently sent a probe to the far side of the moon, but we are not 100 percent sure why you feel hungry right now. And I think that's beautiful. It's one of the most sophisticated regulatory systems in the human body. But we've spent the last 150 years treating it like a primitive urge to beat out of ourselves, biohack out of ourselves, or overcome through sheer will.
Kylee: What you're saying is we can't simplify this to one hack on the internet.
Zoë: Thank God, because you're about to get a 90-minute podcast about it.
A short, weird history of distrusting hunger
Kylee: This is where the cultural piece gets interesting, because the way we talk about hunger right now didn't come from nowhere. Why do we have weird feelings about it?
Zoë: The story of hunger in Western culture is basically the story of one idea: don't trust it. It has worn different hats over the centuries, but the throughline is shockingly consistent. Going back to medieval and early Christian roots, hunger was a spiritual test. Fasting saints, holy anorexia, Catherine of Siena starving herself to death at 33 in 1380 as an act of religious devotion. The hungrier you were, the closer to God. Caroline Walker Bynum's Holy Feast and Holy Fast documents how medieval female saints used food refusal as one of the only forms of agency available to them. So the moral-test frame has been gendered from the beginning. Men could become saints by all sorts of acts. Women mostly starved themselves. Fast forward to the 19th century and it doesn't get more cheerful. Sylvester Graham, of graham cracker fame and officially the Forrest Gump of this podcast, literally believed appetite was a gateway to moral decay. He preached that bland diets would suppress all bodily urges. In the early 20th century, Lulu Hunt Peters, who we covered in the calorie episode, taught American women that their hunger was a patriotic problem. Then we hit the 1960s and 70s, where this gets really interesting.
Kylee: I have a feeling this is a villain origin story moment. Who are we talking about?
Stanley Schachter and the externality hypothesis
Zoë: Stanley Schachter. Most listeners have not heard of him, but he shaped more than 50 years of how we think about hunger and weight. He was a social psychologist at Columbia, hugely influential. In the late 1960s he ran a series of experiments that became known as the externality hypothesis. His basic claim, bluntly summarized in his own terms, was that fat people don't experience real internal hunger the way thin people do. He reasoned that they respond to external cues: the clock says noon, they eat; food is visible, they eat; someone else is eating, they eat. Their internal signals are broken, he argued, so their behavior must be driven by the environment rather than the truth of their own bodies.
Kylee: I'm getting heated just hearing you read this.
Zoë: His famous experiments involved messing with clocks so people thought it was later than it was, and watching whether they ate more. Whether food in a lit display case versus a dark one changed consumption. Whether fasting on Yom Kippur affected larger-bodied Jewish people differently than thin Jewish people. Imagine running that through an ethics board today. He concluded that thin people had functioning internal hunger, while fat people had to use external rules and willpower because their internal signals didn't work and their bodies were fundamentally wrong. This was hugely influential. It was foundational to behavioral weight-loss programs and shaped diet advice for decades. It's the messed-up ancestor of eat on a schedule, don't eat in front of the TV, don't keep snacks visible, eat off small plates, drink water before meals.
Kylee: I hear this stuff all the time from a certain subset of the people I work with. Usually the people who are unhappy with their bodies. Should I buy different dinner plates so I don't eat as much? Should I hide things on the top shelf so I have to work for it?
Zoë: I have done all three of those things. A younger version of me would have said, I am sciencing right now. But we'll get to the reveal.
The science fell apart but the belief stuck
Zoë: These beliefs are pervasive and have lasted a long time despite aging about as well as a pear locked in a hot car. Subsequent research found the effect was much smaller than Schachter claimed. It didn't replicate cleanly. During the replication crisis, researchers tried these experiments again, minus the Yom Kippur component, and they didn't hold up. The distinction between internally regulated thin people and externally regulated fat people fell apart under the lightest scrutiny.
Kylee: Except the idea still remained.
Zoë: We now understand that everyone responds to external cues. Whatever body size, people are all over the spectrum in how they experience hunger. Thin people respond to clocks. Thin people eat popcorn at the movies when they're not hungry. The original premise was that there are two categories of people with fundamentally different hunger systems, and just one of them is wrong. The science was discredited, but the cultural premise has been extremely sticky. The idea that some people's hunger is fundamentally broken, and that they need external rules to eat correctly, became a load-bearing assumption of basically every diet program that followed. It undergirds points systems, calorie-counting apps, macro tracking, time-restricted eating, and the rest. The interventions look different, but the underlying belief is identical: your hunger can't be trusted and you need external scaffolding to tell you when, how, and what to eat.
The Minnesota Starvation Experiment
Kylee: Let's get into the science, because we keep saying hunger is a real signal we can trust. What do we actually know?
Zoë: This is where, with apologies to our listeners, I have to bring up the Minnesota Starvation Experiment again. It's the dark Forrest Gump of the podcast; it keeps popping up. Ancel Keys, at the University of Minnesota from 1944 to 1945, had 36 conscientious objectors volunteer to be semi-starved for six months as part of research on how to refeed concentration camp survivors after the war. They ate a restricted diet that, alarmingly, is not even that low by some modern diet standards, which should make all of us cringe.
Zoë: What I want us to sit with is what happened to these men. Their bodies adapted, their metabolism dropped, and they lost on average about a quarter of their body weight. Their psychology fell apart. Food became their entire personality. They dreamed about food. Many started collecting and recreationally reading cookbooks and couldn't concentrate on anything else. Some would go to restaurants just to watch other people eat.
Kylee: This is eating disorder behavior.
Zoë: Exactly. Reading it, I thought, this is me and my friends in college.
Kylee: This is why, when you assess someone for an eating disorder, there are questionnaires with a lot of these questions, like how much time you spend thinking about food throughout the day.
Zoë: It reminds me of how people are getting really good at smuggling an eating disorder into more culturally accepted scaffolding. No, I actually love food, I love to cook, I have so many cookbooks. Sure you do.
Kylee: And I'm like, do you eat the food that you cook? That's usually the next question.
Zoë: A lot of these men developed obsessive food rituals, like cutting food into tiny pieces or adding water to meals to make them last longer. Familiar territory for a lot of us in recovery. Two of the 36 had full psychotic breaks, and one badly injured his own hand during the study and later said he didn't know whether it was an accident. What's really striking is that on refeeding, the participants' hunger did not normalize. They reported being unable to get full. Some ate to the point of illness and still felt hungry. It took many of them months, even years, to normalize after only a few months of restriction.
Kylee: I see this with people. They get scared because their hunger goes up when they start eating more, and they're afraid it'll get out of control.
Zoë: What we're told controlled hunger looks like is, in my opinion, not a healthy version of it. The deep takeaway: hunger is not a personality trait or a willpower test. It's a coordinated biological response that, when your body decides it needs to, will override every higher cognitive function you have. These were subjects screened for psychological stability, motivated, ideologically aligned with the cause. The hunger still broke them. It's strong evidence that the cultural frame of hunger as something you can simply override through discipline is biologically fantastical.
Leptin, 1994, and the off switch that wasn't
Kylee: So then we get to the point where we thought we'd figured it out.
Zoë: In 1994 we discovered leptin, which is shockingly late. Wu-Tang had already put out albums before we knew what leptin was. Researchers at Rockefeller identified the hormone in fat cells that signals to the brain how much energy you have stored. The press heard the simplest fortune-cookie version and lost its mind: this will revolutionize obesity treatment, we found the off switch for hunger. Spoiler: we had not. We'd found one of dozens of overlapping signals. When leptin was given to people with obesity, in most cases it did not produce significant weight loss. Most people with obesity have plenty of leptin; their bodies have adapted to ignore it, somewhat like insulin resistance. Leptin works beautifully in the rare cases of congenital leptin deficiency, which affects a few hundred people on Earth. The lesson, learned slowly over the next 20 years, was that hunger isn't one knob or an on-off switch. It's like a spaceship control panel with dozens of knobs that interact and compensate for one another. That's why every "we found the hunger gene" headline is destined to disappoint. There isn't one single mechanism.
The new science: AGRP neurons and anticipatory hunger
Kylee: We're 80 years past the Minnesota study and 30 past leptin. Where are we now?
Zoë: There's been a big revolution in hunger research in the last 10 to 15 years, and almost none of it has reached the public. People are still arguing about willpower while the neuroscience has moved into completely different territory. I want to go through three things. The first is from Scott Sternson's lab, published in a 2015 Nature paper with lead author Betley. They were studying AGRP neurons in mice. These neurons sit in the arcuate nucleus of the hypothalamus and were known to drive hunger. The textbook model said they respond slowly to long-term energy signals like leptin and ghrelin, ramping hunger up or down over hours. Using optogenetics, which lets you watch individual neurons fire in real time, they saw that these neurons quiet down within seconds of an animal seeing food, not eating it, seeing it. So these hunger neurons turn down their volume before a single calorie crosses the mouse's lips. Your brain is doing anticipatory accounting. The signal you experience as hunger is not just a report on your current energy status; it's also a forecast that updates in real time with new information. So when someone with a complicated food history sees food and feels hunger spike, the underlying biology might be that they were already hungry and the food cue is amplifying an existing state, not creating one out of nowhere. Conversely, "I forgot to eat" might mean their AGRP neurons were quieted by stress, focus, or dehydration mimicking satiety. The system is far more dynamic than "stomach empty equals hungry." And to be clear, this is an animal model, and none of it is permission to ignore your hunger.
Kylee: Your brain is making predictions about how full you are just from looking at food.
Zoë: In microseconds. The idea that hunger is just the slow regulator of long-term energy balance isn't wrong exactly, those neurons do that too, but it was missing an entire fast, predictive layer that turns out to matter a lot for the moment-to-moment experience. Anyone who has waited for a restaurant to bring food, watched them go to the next table, and felt like they might die if they don't get a breadstick knows this.
Kevin Hall, the metabolic ward, and ultra-processed food
Zoë: The second study lets me mention my favorite methodologist, Kevin Hall. He's the working scientist who shows up in almost all our episodes because he's so good at study design. He came from a data-science background, not nutrition. His 2019 Cell Metabolism paper is one of my favorites of the past decade and it's directly about hunger. He locked 20 adults in a metabolic ward for four weeks.
Kylee: Only 20, though, so that's kind of small.
Zoë: Small, but you have to compare it to the alternatives. It's between animal models and observational data. I'd love to see 200 people, but short of convincing the government to fund it and an ethics board to approve it, this is higher quality than observational. Two weeks on an ultra-processed diet, two weeks on an unprocessed diet, randomly assigned which came first. The diets were matched for total calories offered, calories per macronutrient, sugar, sodium, fiber, and energy density. Participants could eat as much or as little as they wanted, and researchers tracked every bite and weighed all the leftovers. On the ultra-processed diet, people ate substantially more per day than on the unprocessed one. They gained weight on the ultra-processed diet and lost it on the unprocessed one. Same calories on offer, same macros, same fiber, very different food. The primary mechanism appears to be eating rate: people ate the ultra-processed food faster, before satiety signals could catch up, and PYY responses were blunted. The food matrix, the physical structure of the food and how it interacts with digestion, appears to alter both nutrient absorption and hormone signaling. So your hunger system isn't just responding to caloric load. It's responding to how your food is structured, how fast it's eaten, and what state it arrives in. The old "calories in, hunger off, calories out, hunger on" model was never close to accurate.
Kylee: That's going to be more confusing for people. They'll think, so I shouldn't eat ultra-processed food?
Zoë: Go back and listen to our ultra-processed food episode. One of the issues is how hyper-palatable these foods are, the food-matrix piece. It's not just that ultra-processed foods make you gain weight. Hunger is complicated, ultra-processed foods are complicated, and the way they interact we're still figuring out. Both things can be true: ultra-processed, hyper-palatable foods can mess with hunger signals in ways that aren't always helpful, and you do not have to throw out all ultra-processed foods forever out of fear that you might have to listen to your body's hunger cues.
GLP-1 drugs, the brain, and food noise
Zoë: The third one isn't a single study, it's a body of research on the GLP-1 mechanism, largely championed by Daniel Drucker, that has reshaped the field over the last decade. Our original understanding of GLP-1, going back to the 1980s, was that it was a simple gut hormone. L cells in the intestine release it in response to food; it slows gastric emptying and boosts insulin release. That was the model for about 20 years, the Honda Civic of hormones. The realization from the semaglutide and tirzepatide era is that GLP-1's effects on hunger are primarily central, based in the brain, not peripheral. There are GLP-1 receptors throughout the brain, particularly in the hypothalamus and brainstem. These drugs cross the blood-brain barrier and act there directly, which we didn't previously know. That's why these drugs reduce what people call food noise. It isn't because your stomach empties slower; it's because they directly modulate hunger circuits in your brain and gut. GLP-1 receptor activation appears to be one of the inputs that quiets that AGRP neuron. So this class of drugs is essentially hijacking a normal physiological mechanism that already exists for turning hunger down, and turning it up to 11. Out of this era we also got formal research on food noise as a measurable phenomenon, using validated questionnaires to quantify intrusive food thoughts. As someone in recovery, I'm excited to see regular people getting a vocabulary for the cognitive load of this. These studies found that intrusive food thoughts vary enormously between individuals, correlate with hunger sensitivity, and decrease substantially on GLP-1 therapy. Something many people experienced, that others didn't believe in, now has a real research literature.
What this means for how we think about hunger
Kylee: So what does this mean for how we should think about hunger?
Zoë: Three things. One, your brain is doing far more anticipatory work than we thought. Hunger is not a simple energy report; it's a constantly updating prediction that incorporates visual cues, social context, learned associations, and current physiology. That doesn't make it less real. Two, what you eat matters at the level of hunger signaling itself, not just calorie count, because Kevin Hall's work basically destroyed the "a calorie is a calorie" model when it comes to hunger. Three, the central role of the brain means pharmaceutical interventions like GLP-1s work at the control level, not the symptom level, which is part of why they produce more durable results than restriction and why "just listen to your body" falls flat for people whose central hunger systems have been altered by chronic restriction, RED-S, pharmaceuticals, or surgery. When you tell people not to listen to their hunger, you're telling them to disobey a complex array of signals from across their brain and body. The headline: hunger is governed by an extraordinarily sophisticated brain-gut-body conversation we are only beginning to map. The cultural framing of hunger as a simple urge you can override is about a million years out of date.
Why some people run hungrier
Kylee: I've heard that some people experience more hunger than others. Is that real?
Zoë: I'll be honest, I always thought of myself as someone who's just hungrier than other people. Growing up, especially around my female friends who were taught to be weird and overthink food, I felt like I was somehow fundamentally hungrier, and it bothered me because it felt like such a feminine thing to want more.
Kylee: It's tough, because people get it in their head that they're eating way more than everyone else. And it makes sense that some people experience more hunger than others.
Zoë: Exactly, because we all have different bodies and brains. It's not like, I had a piece of pizza, that's roughly X calories, so I'll have X hunger response. Like we learned with calorie counting, all of this is infinitely more complicated. Does that come up with clients, people worried they're so much hungrier than everyone? Because I carried a lot of shame about it.
Kylee: A lot of people mention feeling embarrassed because they have to eat more frequently, or feeling broken because they're hungry all the time.
Zoë: Genetic variation matters a good bit here. There are well-documented variants in FTO and other genes that affect appetite, hunger sensitivity, and satiety signaling. People with certain MC4R variants experience genuinely more frequent and intense hunger. So maybe that's me. But I was also a woman living around other women taught to disregard every signal their bodies sent, so while I was screaming at myself on the inside, I have to imagine other people were too.
Kylee: Do you feel hungry in the same way now?
Zoë: I do. I've come a long way in learning to be curious about my hunger and honor it. I went pretty far down the intuitive-eating side, maybe past the point of usefulness. I'm also a competitive ultrarunner, so I do need to eat a lot, and I'm careful not to let that be the reason I'm okay eating more than people around me. I need to eat the amount I need to eat. If I did a long run that day, great. If I didn't, also great. Exercise can be a reason I need to eat more, and it can also be a reason I need to not eat less.
Kylee: That's where people get into, it's a rest day and I felt more hungry, but I shouldn't eat because it's a rest day.
Zoë: As if your body resets every 24 hours. It doesn't. I struggled with this growing up, because I was taught it was unladylike to be hungry, to be a desirous person, to be a woman who listens to her body and acts accordingly, especially in the South and particularly the evangelical Christian South. Think about hunger the way you'd think about having a higher resting heart rate, or being colder than other people at the same temperature, or being taller. And there can be huge variation within one person over time. Your hunger today is not your hunger six months ago. If you don't sleep well, your body will drive you to consume more the next day, because sleep deprivation increases ghrelin and decreases leptin. More gremlins, less leprechaun. Stress activates cortisol, which has complicated, individual effects: acute stress tends to suppress appetite, chronic stress often increases it.
Kylee: Mine suppresses.
Zoë: Mine increases. The menstrual cycle is huge too. In the luteal phase, resting metabolic rate goes up, hunger goes up, and food preferences can shift toward higher-energy foods.
Kylee: So many people say, I know my period's coming because I'm so hungry. So eat more.
Zoë: I have a solution for you. It's my good friend, pizza. Aging changes the system too. Older adults often have blunted hunger signaling, which is part of why malnutrition in the elderly is a serious problem. And a history of restriction, dieting, or eating disorders can affect the system long-term. With a long history of dieting you might have down-regulated hunger and satiety signaling that can take years to recover, if it ever fully does.
Kylee: I've seen the opposite happen too. There's a range as the body tries to recover and doesn't yet know how to adapt.
Zoë: RED-S affects so many systems across the body, and hunger is the result of so many systems, so I'd imagine there are fascinating and challenging collisions. If someone says, I'm always hungrier than my partner, or I get way hungrier the week before my period, you're not making it up, it's not in your head, and it doesn't mean you're weak. Your system is genuinely different in that moment.
The willpower myth
Kylee: Okay, willpower. I want to scream every time I hear the word willpower, or cheat meal. With willpower, people feel a moral failure if they can't override their hunger. Where does that come from?
Zoë: Willpower does a ton of work in our culture and none of it is scientific. What do you hear from clients?
Kylee: I had someone who talked about needing more willpower for God, and not wanting to eat as much. That came up in our first session. There's also, and I hate to put a gender on it, a lot of the male clients I work with use willpower a lot. A lot of CrossFit and bodybuilding history.
Zoë: We women have been doing the diet-culture dance for a while, we know the steps. Guys are more recently catching up. The most famous willpower research is Roy Baumeister's ego-depletion model from the 1990s and 2000s. The theory was that willpower is a finite resource that depletes with use but can be restored by glucose, which on the surface sounds great, I just need more candy. At the time it was a huge deal, replicated in dozens of studies, cited everywhere. Then in the 2010s the replication crisis hit ego depletion like a truck. Large, preregistered replication studies failed to find the effect, and a 2016 meta-analysis concluded the original effect was either much smaller than reported or didn't exist, with signs of p-hacking. That doesn't mean self-control is fake. But the scientific framework behind the pop-psychology version of willpower is probably not real. What's actually happening when people "fail" at willpower around food is better described as a signal mismatch: they tried to use the prefrontal cortex to override a homeostatic hunger signal, and the body usually wins, because that signal evolved to keep you alive and is very strong. There's also compensatory eating after restriction, when the body responds to perceived scarcity by ramping up hunger and reward responses. That's not weakness, that's protection. One of the best ways to make yourself fixate on a food is to restrict your access to it. Not a bad thing. We have these reward systems for a reason. Just be cool with the amount of pizza you eat.
Zoë: Sleep deprivation, chronic stress, and under-eating earlier in the day all produce later loss-of-control eating. So when people get afraid of that hunger response, there's usually something further up the chain. People with "great willpower" around food usually have one of three things going on: their body genuinely sends weaker hunger signals, often genetic; their environment makes eating less salient; or they're in active restriction, and the cost is hidden in food preoccupation, mood disruption, or downstream binge episodes. What I once perceived as willpower or a lack of hunger in other people was just the calm surface above a lot of turbulence.
Kylee: I get to see what's under the surface. A lot of people say, I lack willpower, I really try, but then I have these binge episodes on cheat days.
Zoë: The Minnesota men had willpower by any definition. They were chosen for it and ideologically motivated, and after six months their hunger was running the show. When we tell a regular person their problem is willpower, we're holding them to a standard that broke trained subjects in a lab who had no other job or life stress.
What hunger cues actually feel like
Kylee: Let's talk about hunger cues.
Zoë: How do you help athletes get in touch with their hunger cues? When I was reporting this, I kept thinking, what does hunger actually feel like? I can't feel the neurons firing.
Kylee: For a lot of people, putting it on a one-to-ten scale can help. A one might be nauseous, physically ill, or ravenous. A ten is uncomfortably overfull. The midpoint, a five or six, is neutral: your stomach isn't growling, you don't feel like you need energy, maybe you feel satisfied. There's a lot of challenge here, because people will say, I'm scared of fullness, or I've been told fullness is bad. And if I'm explaining this to somebody who isn't fed, their hunger and fullness cues aren't reliable, which makes it more complicated. It's also complicated for athletes, because exercise, intensity, heat, and long training sessions all alter hunger and fullness cues. There's biological hunger, and then there's practical hunger, where we might not feel the cues but we still need to fuel.
Zoë: It's like asking someone who's lived in the dark what it feels like to be in the light. A lot of people don't trust their bodies. Some internal hunger cues: stomach emptiness, growling, a drop in blood glucose causing irritability or shakiness, low energy, thinking about food, salivation, difficulty concentrating, even a mild headache. Then there are learned, external cues that get confused with hunger, not always in a bad way: time of day, the sight or smell of food, social pressure, emotional triggers, boredom, screen time, and dehydration, which we mistake for hunger constantly.
Kylee: I've worked with a lot of people who have rigid time-of-day rules: I have to eat at 8, then 10, then noon, and nothing outside those windows. Those people typically have a harder time understanding hunger and fullness, because they don't trust their bodies.
Zoë: For a lot of adults in industrialized cultures, the internal and external categories have been blended for so long they feel identical, and many of us have spent years intentionally scrambling our own signals. Kids often start with pretty clean hunger cues, but culture trains it out of them by middle school through scheduled eating, "finish your plate," diet talk at home, and peer body comparison.
Kylee: I work with some high schoolers, and it's, my friends aren't eating, so I don't want to eat in front of them. And the scheduled eating: your lunch period is at 10:30 in the morning, and you can't have food in the classroom.
Zoë: No wonder people enter adulthood asking, what is a hunger cue? For people who've spent years overriding hunger, through dieting, eating disorders, or just being too busy to eat, it's easy to lose access to the internal signal, because the signal is still firing but the conscious connection is broken. Is there anything you do to help clients reconnect?
Kylee: Step back from the numbers and the control and the scheduled eating, and journal about how you feel. What's my energy like? People notice an afternoon energy drop and realize maybe they didn't eat enough earlier, or they were skipping meals. Using the number or description system helps them name things and spot patterns. For people with eating disorders it's very complicated, because we can't really engage in any of that until someone is well into recovery.
Zoë: When I was in recovery, it felt like learning a whole new culture. My body tells me it wants food, and I just give it food? It was scary, but on the other side is connection and pizza and not being an injured person all the time. It's complicated, and there are limits. I found intuitive eating helpful at first, and then as I became an athlete it failed me in key ways. People active in an eating disorder often can't use hunger cues as the primary input, because the signal is suppressed, scrambled, and unreliable, so they need external structure during recovery, guided by a professional. You don't DIY rebuilding your hunger cues. People in RED-S or chronically under-fueled also tend to have suppressed hunger as a protective response; if you wait until you feel hungry, you're often already in a deficit. People who are post-bariatric surgery or on GLP-1s have a pharmacologically or surgically altered hunger system, so the standard advice doesn't apply cleanly. As much as I loved "just listen to your body" for a little while when I was younger, I have more complicated feelings about it now.
References
Baumeister, R. F., Bratslavsky, E., Muraven, M., & Tice, D. M. (1998). Ego depletion: Is the active self a limited resource? Journal of Personality and Social Psychology, 74(5), 1252–1265. https://doi.org/10.1037/0022-3514.74.5.1252 (the original ego-depletion / willpower model)
Betley, J. N., Xu, S., Cao, Z. F. H., Gong, R., Magnus, C. J., Yu, Y., & Sternson, S. M. (2015). Neurons for hunger and thirst transmit a negative-valence teaching signal. Nature, 521(7551), 180–185. https://doi.org/10.1038/nature14416 (the Sternson-lab AGRP paper named in the episode)
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Carter, E. C., Kofler, L. M., Forster, D. E., & McCullough, M. E. (2015). A series of meta-analytic tests of the depletion effect: Self-control does not seem to rely on a limited resource. Journal of Experimental Psychology: General, 144(4), 796–815. https://doi.org/10.1037/xge0000083 (the meta-analysis finding the effect near zero once publication bias is accounted for)
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