Originally published April 2010. Last reviewed and updated by the Precision Nutrition editorial team, June 2026.
Ever wonder what makes you hungry?
Why some foods look more appealing than others? Why you’re always hungry for dessert? Or why you might open the fridge full of food, then stand there and say, “We have nothing good to eat!”?
The body is not a simple container of calories that can be added and subtracted. We’re driven by a complex play of chemicals that orchestrate food intake, desire, and food associations.
Appetite is our desire to eat. It’s controlled by a complicated interaction of hormonal signals that originate from fat cells, cells of the pancreas and cells in the gut. These signals are also processed through cognitive and emotional filters.
For example, if you ask a North American, “What’s comfort food?” they might say “macaroni and cheese”. Pretty sure you wouldn’t get the same answer in, say, Mongolia or Rwanda.
The foods we crave are a product of physiology and psychology. Appetite is different from hunger. Hunger is our physical need to eat. You can want to eat but not need to eat (for example, wanting to eat dessert after a big meal). Or you can need to eat but not want to eat (for example, losing your interest in food when you’re stressed).
How does this all work? And who’s driving the bus?
For anyone who has purposefully controlled food intake to lose weight, they know how powerful counter-regulation can be. Much of this seems to be mediated, or shaped by, our neuro-endocrine system, aka the interaction between our brains and our hormones.
When we lose stored fat, our body mounts a major response to conserve energy and boost appetite, defying further weight loss and encouraging regain.
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Why is appetite regulation important?
If we under- or over-eat, problems arise. We can become malnourished, obese, fail to repair, lose reproductive ability and/or develop diseases.
For those who want to decrease body fat, a conscious restriction of energy intake is generally unsuccessful (more than 90% of the time weight is regained – and then some).
On the other hand, some people are successful at losing fat. Why does the first group fail and the second group succeed?
Finding the master controls
One of the best ways to grasp the importance of appetite regulation is to knock it out. In other words, the best way to learn what a hormone/gland does is to get rid of it and see what happens.
For instance, a simple defect in the hypothalamus, located in the brain, might mean someone may eat or starve themselves to death, like with Prader-Willi Syndrome. This tells us that the hypothalamus has a big role to play.
In fact, the hypothalamus is the ringmaster of appetite, but there are lots of acts in the circus. Major players in appetite regulation include insulin, thyroid hormone, glucagon like peptide-1 (GLP-1), endocannabinoids and cortisol. If any of these get out of whack, you can lose your life, literally.
We’re still learning about new pathways and chemicals involved in appetite, but below is a list of what we’ve got so far.
Orexigenic means appetite-stimulating, while anorexigenic means appetite-suppressing. (Both of these come from the Greek root orexis, or desire/appetite — notice here how “wanting to eat” is important.) Simple, huh? Not.
What you should know
Appetite is governed by two organ systems of the body, the endocrine system and the nervous system — their connection is sometimes known as the “neuroendocrine system”.
The endocrine system & appetite
Quick — what’s the largest endocrine organ in the body?
You might be surprised: it’s the GI tract. Yep, your gut is the biggest hormone player on the block. It produces and processes all kinds of hormones ranging from neurotransmitters to anabolic storage hormones to sex hormones.
The organs of the endocrine system are sensitive to changes in the body, and, in response to these changes, send out messengers (called hormones) to tell the body how to respond. These energy regulating hormones are classified into either short term or long term.
The vagus nerve is the key connection between the gut and the brain.
Various hormones play a role in appetite regulation and energy balance, including:
| Hormone | Origin and role |
| Calcitonin |
|
| Amylin |
|
| GLP-1 |
|
| Leptin |
|
| Gastrin |
|
| Secretin |
|
| Cholecystokinin (CCK) |
|
| Gastric inhibitory polypeptide (GIP) |
|
| Motilin |
|
| Somatostatin |
|
| PYY 3-36 |
|
| Ghrelin |
|
The nervous system & appetite
The nervous system acts via nerve impulses and neurotransmitters (hormone-like chemicals), directing nervous tissues, smooth muscles, and other organs of the body to move, mix, and propel foodstuffs that enter the digestive system.
While some appetite control originates from nervous and hormonal connections between the digestive system and the brain, the digestive system possesses its own, localized nervous system, referred to as the enteric nervous system.
It’s the “mini-brain” located in your gut. In this mini-nervous system, neurotransmitters are released, which can relay, amplify and modulate different signals between cells of the body.
Some of the neurotransmitters involved with appetite regulation include:
| Neurotransmitter | Role |
| Endocannabinoids | These participate in glucose and insulin metabolism in muscle and fat tissues. When endocannabinoid receptors are blocked, insulin sensitivity is improved. This can lead to less food intake and fat mass. When food intake is decreased, there seems to be an upregulation of endocannabinoid receptors and serious hunger is soon to follow (think: smoking weed and making a Taco Bell run). It seems that a diet with lots of omega-6 fats can promote endocannabinoid production, while a diet higher in omega-3 fat can inhibit it. Researchers are trying to develop endocannabinoid receptor blockers for humans. |
| Gamma aminobutyric acid (GABA) | GABA can act as an excitatory or inhibitory neurotransmitter depending on which cell receptor it binds to. The chief role of GABA is to stimulate GI motility and contribute to GI wall mucosal function. |
| Norepinephrine | Decreases digestive activity, which makes sense during fight or flight situations. When immediate, decisive, or aggressive action is required, digestion is a low priority. Stress not requiring immediate fight or flight type responses (such as deadlines, relationship challenges, etc.) also provokes norepinephrine release and this can impair digestive function. |
| Acetylcholine | In the digestive system, this neurotransmitter is responsible for stimulating digestive activity. It acts to stimulate smooth muscle contractions in the digestive organs and help move food through the GI tract. It also stimulates the release of other digestive hormones, dilates blood vessels, and increases intestinal secretions. It runs counter to the actions of norepinephrine. |
| Neurotensin | As dietary fat reaches the last section of the small intestine, cells located in the intestinal walls release neurotensin. It relaxes the lower esophageal sphincter, blocking the release of stomach acid and pepsin to regulate GI contractions. |
| Neuropeptide Y (NPY) | This neurotransmitter is present in both the brain and the enteric nervous system. In the brain, its action is to stimulate hunger and food intake while discouraging physical activity. Working in conjunction with leptin and corticotropic releasing hormone, this neurotransmitter plays a role in metabolism and body composition. It’s typically released when body fat is low or food is scarce. In the gut, Neuropeptide Y generally slows gastric emptying and transit time. |
| Serotonin | Released both in the brain and the enteric nervous system. In the brain, serotonin is linked to modulating anger, aggression, temperature, mood, sleep, appetite, and vomiting. Following meals, serotonin concentrations reach a maximum within 1-2 hours.In the gut, serotonin is produced by cells located in the small intestine. In this capacity, serotonin increases small intestinal motility, reduces stomach acid production, and, in high amounts, can cause nausea. This is why anti-depressant drugs like Prozac can sometimes lead to diarrhea and nausea. These drugs make more serotonin available not only in the brain (where they exert their anti-depressant effect), but the gut, where they can cause serotonin excess. |
| Nitric oxide and Substance P | Found in the brain and enteric circulation, these compounds are associated with vasodilation in the gut, assisting in more blood flow for nutrient delivery/uptake. |
| Vasoactive intestinal peptide (VIP) | VIP is important to the digestive process through its ability to inhibit the release of gastrin, inhibit the secretion of acid, stimulate bicarbonate secretion from the pancreas, induce smooth muscle relaxation and vasodilation, stimulate pepsinogen release, and stimulate the secretion of water and electrolytes into the small intestine. Most of these functions are responsible for slowing down stomach activity while stimulating intestinal activity. |
Other gut-brain interactions
Appetite medications
Sibutramine is the only regularly used anti-obesity medication. It acts as a norepinephrine-serotonin reuptake inhibitor. It causes hazardous side effects with only minimal impact on weight.
Rimonabant is a cannabinoid type 1 receptor antagonist. It isn’t on the market since it causes psychiatric disturbances and increased suicide risk. And really, as of now, obesity meds don’t help at all. Patients might lose 10-15% of body weight, but 6 months later the weight is back on.
Exercise
Physical activity plays an important role in appetite regulation. Some data show that appetite responses to exercise are strongly influenced by energy balance in men, but less in women.
Those who regularly exercise become more efficient at using body fat as a fuel source, and this can help with regulating appetite (since people that don’t exercise use more carbs and blood sugar fluctuations = appetite swings). Exercise can moderate levels of leptin, ghrelin and insulin. (See leptin cycle below.)
Also, PYY 3-36 might increase with exercise, especially with stuff like walking, jogging and biking (rather than higher intensity stuff). Moderate to intense exercise transiently suppresses appetite.
Bariatric surgery
Many of the gut hormones and neurotransmitters mentioned seem to be affected (at least temporarily) after bariatric surgical procedures. This may promote satiety, at least in the short term.
What is eating the right amount?
Ideally, our physiology regulates our appetite perfectly. We evolved to eat when we’re hungry, and stop when we’ve had enough.
Of course, it doesn’t always work that way in our modern society.
Appetite has a massive “real life” component. Subtle eating cues can trump physiology. These can include:
Cues from our physical environment
For example, the size of dishes, how close the food is to us, etc. One study found that people ate more from a candy dish right in front of them but much less from a candy dish 6 feet away. They also ate more from an uncovered candy dish than a covered candy dish.
Cues from our oral environment
- We like certain tastes and textures.
- We like sweet, fatty, and “umami” (savoury) things.
- We like creamy textures and crunchy textures.
- We also like multiple tastes and textures together, such as sweet-salty.
Cues from other senses
As the saying goes, “You eat with your eyes first.” We like food that looks pleasing, and we favour certain colours (ever seen candy with boring gray packaging?). Our smell is closely bound to our appetites as well as our memories and emotional associations. There’s a reason that Cinnabon smells so delectable — it’s part of a deliberate strategy to lure us in.
Cues from our social environment
- family, friends, peers
- cultural messages about when and where it’s OK to eat
Cues from our emotional and psychological environment
- stress
- anxiety
- desire for comfort
- symbolic associations with a certain food, e.g. “baking cookies makes me feel happy”
Cues from our familiar habits and routines:
- morning coffee in our special mug, or “the usual” at the coffee shop
- being rushed in the mornings, so stopping at McDonald’s drive-thru
- Friday beers after work with the boys
- snacking in front of the TV while watching our favourite shows
- cake at birthday parties
- mom’s casserole at holidays
- etc.
Sometimes these cues are helpful. Most have an evolutionary purpose. For example, knowing what food looks and smells good can prevent us from eating something that’s gone rotten. Eating when we weren’t hungry, but when food was available, would be helpful in a context when we couldn’t be sure where our next meal was coming from.
However, in 21st century society, our evolutionary survival mechanisms don’t work very well. Now, we’re surrounded by good-looking food that is available to us 24/7. We’re chronically stressed and seeking comfort. Our eating impulses are out of whack. Our biology no longer matches our environment.
When we are perfectly in tune with appropriate appetite and fullness cues, we eat when physically hungry and stop when satisfied (not stuffed). We maintain a healthy body weight.
When we are not in tune with these cues, our health and weight suffer.
Under-eating and over-eating
There are many reasons why we might under- or over-eat more than we need.
Under-eating might occur because of:
- social pressures (e.g. among women to be thin)
- stress
- a desire to restrict food to feel “in control”
- over-preoccupation with “health”
- rigid restriction/elimination of certain foods
Over-eating might occur because of:
- social pressures (e.g. wanting to fit in at social events)
- stress
- feeling “out of control”
- a desire for comfort or self-soothing
- disrupted biological routines such as lack of sleep or shift work
- highly palatable tastes such as fatty and sweet foods
- food availability: the food is there and it ain’t gonna eat itself!
Cultural overeating
Eating when hungry and stopping when satisfied is something that nearly all mammals are programmed to do from birth. Yet, in the U.S. we tend to “unlearn” this and only stop eating when we are “full.” Many cultures discourage this.
Throughout India, Ayurvedic tradition advises eating until 75% full.
The Japanese practice hara hachi bu, eating until 80% full.
Islamic guidance from the Qur’an indicates that excess eating is a sin.
The Chinese specify eating until 70% full.
The prophet Muhammad described a full belly as one containing 1/3 food, 1/3 liquid, 1/3 air (nothing).
There is a German expression that says, “Tie off the sack before it gets completely full.”
“Drink your food and chew your drink,” is an Indian proverb that encourages us to eat slowly enough and chew thoroughly enough, to liquefy our food, and move our drink around our mouth and thoroughly taste it before swallowing.
When someone is finished eating in France they don’t say “I’m full,” rather, “I have no more hunger.”
And countries outside the U.S. emphasize that eating should be pleasurable and done in the company of others.
Homeostasis: The body’s secret weapon
The body likes things to stay the same, aka homeostasis. When homeostasis is interrupted, the body tries to self-regulate and get back on track.
With body weight, there are internal challenges in maintaining homeostasis. As nutrients are used, they must be replaced. Our bodies say “Please replenish these nutrients”, aka “Eat.” Our bodies say “Thank you, that’s enough for what I require”, aka “Stop eating.”
When we honour homeostatic hunger signals, we achieve optimal health.
- If we eat when we are not hungry, the distraction and pleasure are only temporary; consequently, we have to eat more to feel better, feeding the cycle.
- If we do not eat when we are hungry, our body gets us back eventually by cranking up our appetite signals and smothering our fullness signals. The biggest trigger of binge eating? Dieting.
Mindful/intuitive eating
Have you ever observed an infant eating? They eat when they are hungry, and they stop when they’ve had enough. If they don’t like something, they spit it out.
Mindful/intuitive eating is kind of like that.
When we eat this way, it promotes physical and psychological well-being. Physically, it’s gratifying to not feel overly stuffed or empty. Psychologically, it’s gratifying to be able to honor the internal cues of hunger and satiety, much like it’s psychologically gratifying to drink water when thirsty, get warm when cold, urinate when the bladder is full, or breathe after diving 8 feet to the bottom of a pool.
Years of mindless eating, restrictive dieting, and the “good” versus “bad” food mentality can warp the way we respond to internal body signals.
When the idea of “bad” food is discarded, it often removes the punishing cycle of restricting and gorging. Why? Because when we acknowledge that a food is available to us whenever we want, we can begin to select a variety of foods we enjoy and become the expert of our own body.
Three key components of mindful/intuitive eating are:
- Unconditional permission to eat
- Eating primarily for physical rather than emotional or environmental reasons
- Relying on internal hunger and satiety cues
Why is eating the right amount so important?
If we don’t eat the right amount for our needs, our bodies will try to self-regulate to maintain homeostasis or meet evolutionary needs. If we’ve under-eaten, we might compensate with a binge. If we’re over-eating on highly palatable foods, our bodies might say “This is great! Have more, just in case of famine!”
While many people periodically eat in response to sensations other than physical hunger, this type of eating becomes destructive when it’s the principal way of dealing with feelings or going along with easy food availability. If we eat each time we get lonely, sad, bored or happy, or if food is around us, we’re in trouble.
The problem of “dieting”
Few nutrition professionals question the wisdom of using food deprivation as a means to manage weight. “Eat less” is the most common advice given to people wanting to lose weight.
Still, it doesn’t seem to be working for anyone. Some are beginning to acknowledge that “dieting” — as in significant, short-term food restriction — doesn’t work for sustained health and weight management.
“Dieting” can increase food cravings, food preoccupation, guilt associated with eating, binge eating, weight fluctuations, and a preoccupation with weight.
We might get into a cycle of “deprivation mentality”: we restrict, then lose control, then vow to “get back on the wagon” (ie. restrict further), then lose control again, then apply an even more rigid control, then lose control… over and over and over.
“Dieting” can work in the short term. People can and do lose fat and weight… for a while. But more than 90% of individuals who lose weight will regain it within 2 years.
“Dieting” doesn’t address either the underlying deprivation-binge mindset, or the real problems of why you’re overfat in the first place.
Mindful/intuitive eating as an alternative
Mindful/intuitive eating asks “Why am I eating?” and “Am I truly hungry?” Thus it can reduce binging and emotional eating episodes. The more mindfulness and meditation someone uses, the more weight they can lose (and keep off).
Mindful/intuitive eaters aren’t obsessed eaters. Rather, they simply appreciate the value of food as opposed to hurrying through a meal. As they stop judging themselves, they are more present and aware of what they are doing.
What you should know
Learning body signals
Figuring out satiety cues involves trial and error. The level and intensity of hunger can vary, as can knowing what foods/amounts will satisfy hunger. How the body responds to food is going to be different for everyone. It can also be different at different times of the day.
As I mentioned above, consider children. Kids generally push food away when they’re content. And they know when they don’t like something. Intuitive/mindful eating is about tapping back into that wisdom.
Be aware of how you feel physically, mentally, and emotionally. For example:
Physically
- Is your stomach growling?
- Do you have a headache
- Are you feeling shaky or irritable?
- Do you feel “stuffed”?
Mentally
- Are you thinking, “I want to eat this” or “I need to eat this”?
- Are you aware of what you are eating or are you just plowing in the food while you do something else?
- If your eating routine is disrupted, are you upset because it’s a change in habit, or because you’re genuinely hungry?
Emotionally
- Are you anxious or stressed?
- Are you happy or sad?
One way to approach eating may be to start with a typical meal and then tune in to how you feel physically, immediately after and every hour after that meal.
- Immediately after eating: If you’ve eaten the right amount for optimal health, you’ll likely feel a slight level of hunger, but still content. It takes about 20 minutes for the satiety signal to go from the gut to the brain. The composition of a meal can influence satiety, so include real/whole foods with fiber, protein, and fat (and balance omega-6 with omega-3).
- About 60 minutes after eating, you should feel satisfied with no desire to eat another real food meal.
- When you approach the 2 hour mark, you may be starting to feel a little hungry, and could probably eat something, but it’s not a big deal yet. If you are feeling quite hungry, you may not have had enough food or enough of a given type of food to hold your satisfaction.
- At 3 to 4 hours, you should be feeling like it’s about time to eat again. Your hunger should be stronger, and will vary depending on when you exercised and what your daily physical activity level is. If you aren’t hungry yet, you probably had a bit too much food at your previous meal.
- After 4 hours, you’re likely hungry and ready to eat. This is when the “I’m so hungry I could eat anything” feeling kicks in. If you wait much longer, chances of making a knucklehead food selection goes up dramatically. It’s important to have nutritious and appealing foods available.
There is variability with all of this, but getting to a point where you’re slightly hungry between meals is a healthy sign. If you are eating every 2-4 hours without ever feeling a level of hunger, you are likely eating more than you need.
It’s OK to be hungry sometimes
If you’re trying to get or stay lean, it’s OK and normal to feel hungry occasionally.
It’s important to accept this feeling because it’s not going anywhere. Nor would that really be a good thing since hunger plays a vital biological function.
“Hunger is not an emergency.” — Judith Beck
Choose the right foods
We didn’t evolve with highly processed foods. These foods confuse our natural appetite mechanisms.
Eating a dessert on its own will often increase the craving for more. It’s not that you necessarily need more processed carbs, just that you’ve triggered the body into thinking it wants more. Processed foods trigger our natural reward systems (think: opioids and dopamine released in the brain) and we want more (and more).
Unprocessed foods help keep hunger/satiety cues clear, and it’s easier to make adjustments. Remember, if you’re not hungry enough to eat broccoli, you’re probably not hungry.
Incorporate activity properly
Regular exercise makes us more efficient at using body fat, which can help balance appetite.
The type of activity can determine our appetite. Intense exercise, such as heavy weight training or high-intensity interval training, tends to suppress appetite in the short term, while low-intensity, endurance-type activity tends to stimulate appetite. (Ironically, many people do a lot of “cardio” when trying to lose fat, which can end up making them more likely to overeat!)
Still, some people play games when it comes to exercise and eating. They might allow themselves more food because they exercised, regardless of hunger changes. This “reward” system can be fickle and create a negative relationship with eating. “Exercise bulimia” occurs when we engage in a cycle of overeating then overexercising to “compensate”.
Practicing yoga can help with mindful/intuitive eating and assist in overall body satisfaction. This makes sense since yogic philosophy aims to unify mind, body and spirit.
Summary and recommendations
► Eating a reasonable amount of food each day to support health and regulate appetite goes beyond willpower and calorie counting.
► Acknowledging the information our body relays about hunger and fullness can be helpful in regulating appetite. Only when our physiological foundation is polluted with excess stress, weight, processed foods, and/or lack of physical activity will appetite balance become defective.
► The appropriate release, response and balance of gut hormones and neurotransmitters seem to depend upon a diet consisting of whole foods.
► While we don’t know exactly what it takes to manage appetite, we do know the human body doesn’t have a longstanding relationship with processed food products, and they might short-circuit our appetite regulation pathways.
► Social rituals of eating, such as eating while distracted (e.g. while driving or watching TV), eating too rapidly (e.g. while rushing to do errands), or always having dessert may also affect our desire to override natural hunger and fullness cues.
► Dieting and cognitive control of food intake may actually lead to more weight gain, disease, and disordered eating patterns.
► Intuitive/mindful eating involves:
- Slowing down the pace of eating (e.g., break during bites, chewing slowly, etc.).
- Eating away from distractions (e.g., television, books, magazines, work, computer, driving).
- Becoming aware of the body’s hunger and fullness cues and utilizing these cues to guide the decision to begin and end eating as opposed to following a regimented diet plan.
- Acknowledging food likes and dislikes without judgment.
- Choosing to eat food that is both pleasing and nourishing, and using all of the senses while eating.
- Being aware of and reflecting on the effects caused by non-mindful eating (e.g., eating when bored or lonely or sad, eating until overly full).
► The goal of a meal is to finish feeling:
- Better than when you started
- Satisfied
- Able to move on (not think about food until you are hungry again)
- Energized enough to exercise and stay active
- Mentally focused
► Eating too much or too little will result in variations of the normal responses mentioned above. This may include:
- Lethargy
- Fullness or bloating
- Anxiety or jitters
- Food cravings, even when physically full
- Headaches
- Mentally sluggish
Extra credit
- Estrogen deficiency might result in a higher energy intake and increased body weight. Food intake varies across the menstrual cycle. Women tend to eat more in the luteal phase (the premenstrual period) compared with the follicular phase.
- Testosterone (directly) seems to have little effect on food intake, although many people supplementing anabolic doses of testosterone (e.g. bodybuilders) do report increased appetite.
- Including a balanced intake of omega-6:omega-3 fats can help with appetite regulation.
- Protein and fibre all seem to help control appetite.
- Refined carbohydrates, on the other hand, appear to increase appetite.
- Dietary fat has mixed results; when combined with refined carbohydrate it seems to increase appetite while on its own or combined with protein, it typically decreases appetite.
- Elderly people have less appetite than young people from not only decreased energy expenditure but also from mechanisms potentially involving sex–steroid balance as well as altered CNS signaling to and from peripheral organs.
- It’s now recognized that overfat individuals have lower blood concentrations of vitamins and minerals compared to leaner individuals. This may lead to a greater appetite and changes in fat deposition.
- What type of person is most likely to eat unhealthy food? A restrained eater depriving themselves of a forbidden food. This is the psychological phenomenon of disinhibition. Habitual disinhibition — in other words, regularly overriding our natural fullness cues — is the factor most closely linked to weight gain.
- The goal of mindful/intuitive eating is to master the process of eating and not focus on weight loss. For dieters, this task is extremely difficult.
- If you have any doubts about whether you’re hungry, you’re probably not.
- Hunger is physical. Over-eating is psychological, mental, and emotional.
- When your true needs are unmet, triggers will return again and again.
References
Click here to view the information sources referenced in this article.
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