Appetite, as distinct from hunger, encompasses so much more than a biological urge to correct low blood sugar. It is the desire to eat. Our relationship with food, pleasure, and nourishment exists in this gap between biological hunger and our desire to eat. It is a complex, dynamic interplay between our hormones, senses, habits, past experiences, future expectations, and available food. Let’s take a look at the science of appetite to discover more about this gap.
Nature prioritized eating as so essential to our survival that the process is linked to three places in the brain—1) the hypothalamus, which governs metabolism; 2) the limbic center of our emotion brain, which governs dopamine for pleasure; and 3) the hind-brain, which wires the behavior of eating into our unconscious habits so we don’t have to think about it. This creates a powerful neural circuit that overrides the cognitive brain to ensure that we continue to eat again and again (there are obviously some extreme conditions that bypass this mechanism, such as anorexia, life threatening medical illnesses or severe depression).
The science of appetite includes being in a body equipped with some or all of the 5 senses. What we smell, see, taste, touch and hear affects what we crave and desire. Our senses may dull from a monochrome palette of food, and come alive in a sea of colorful nutrients.
We also have intuition, or what we call the 6th sense, or gut wisdom. Science has shown that we possess in our gut nearly 90% of the neurotransmitters found in the brain. These neurotransmitters communicate with each other to maintain a dynamic homeostatic equilibrium. Neuroscience is even linking a gut microbiome full of harmful bacteria to immune problems, autism, and mood disorders such as anxiety and depression. What’s swimming in our gut affects what our bodies hunger for.
One mechanism that regulates appetite is the balance between hormones, particularly ghrelin—“the hunger hormone”—and leptin—“the satiation hormone.” Grhelin tells our brains that we are hungry when we perceive our bellies to be empty, and it helps to regulate the rate at which we use our energy. If we were to use our energy too fast, we would dwindle away and spend our short time on Earth searching, in panic, for food. If we use it too slowly, we’d constantly feel weighed down and lethargic. So our bodies come equipped with a checks and balances system for hunger. In addition, we’re wired with powerful mechanisms to fulfill that hunger.
Our bodies are designed to break whole foods down into energy through the process of digestion. As ghrelin, blood sugar levels, and sensorimotor signals tell the brain that our stomach is empty, we begin to feel hungry, and we initiate our habitual search to satisfy our hunger. Our senses of sight and smell stimulate gastric acid secretion and motility as we hunt for food, preparing the body for consumption. Taste, and the sense of texture, release salivary enzymes in the mouth while we chew, which begins to break down the food for easier digestion further along the alimentary canal. This sends a flood of the dopamine we had been craving into our brain and creates that powerful feeling of pleasure and satisfaction in our bodies.
Now the food gets taken over by our involuntary smooth muscles. The esophagus contracts to move the food from our mouths to our stomachs. Our stomach transforms the bites of food we’ve chewed into a paste, called chyme, through acids and enzymes. Nutrients from our food are absorbed in our small intestines (with the help of the pancreas, liver, and gallbladder) through enzymes that break down proteins, fats, and carbohydrates for use in our bloodstream. The large intestines eliminate waste, recycle extra water and electrolytes back into the body, and store bacteria. The useful bacteria synthesize essential vitamins and nutrients, break down last bits of food and protect against harmful bacteria.
The more present we are when we are eating, the more accurately we can read our bodies cues and aid our digestion. However, things like traumatic experiences, biological or hormonal imbalances, or unmet psychoemotional or spiritual needs can confuse these signals. Getting clear on where our appetites originate can help us satisfy that hunger more directly.
The science of appetite includes emotional processes as well. Dopamine is the neurotransmitter that drives pleasure and is linked with every addictive process. It’s no wonder the Hindi’s identified the second chakra, a nerve plexus located just below the navel, as the center for all relational issues of food, money, sex, and other people. Our nervous systems are designed to get really happy when we eat food because our ancestors who took advantage of the food available survived long enough for the next meal. This is a good thing. It affirms and ensures our survival. And, pleasure feels good!
However, conditions in first world countries have rapidly changed in a relatively short time, historically speaking. Our appetites are learning or struggling to adapt to the abundance of food, the glut of information at our fingertips, and as many social and career opportunities as we can imagine. Our priorities are switching from simply meeting our biological imperatives, to prioritizing the many resources available. We can often substitute food to satisfy our appetite for other second chakra needs.
The field of psychoneuroimmunology looks at how the body and mind are in constant communication through smaller amino acid chains called peptides (e.g. endorphins), that can affect our mind, emotions, immune system, digestion and other bodily functions simultaneously. The field argues that the body and mind are not separate; the body is simply the unconscious mind. Further, the bodymind is largely responding to shifts in hormones, whether from a thought about our worth, emotions about another person, or biological reactions to hunger. So, whether we’re hungry for a hug or a burger, our body has a cascade of hormones that alert us to these needs. We just may misinterpret which one it wants.
Emotions are neither good nor bad. They’re ingrained in social mammals to alert us to needs. Anger lets us know a boundary has been crossed or abandoned. Sadness tells us we lost something valuable and heightens our hunger for our needs to get met elsewhere (much like grhelin lets us know we’re hungry). Fear let’s us know that something could be threatening to our survival, while joy let’s us know something is life affirming. However, we may have grown up in households or institutions that had rules about some emotions being better or worse. Our responses to emotions may even differ depending on which gender we are or were assigned. Do we stuff our anger, sexuality, or joy with food because there’s a rule we shouldn’t have it? Our habits about our emotions—whether we bottle them up, relate to them with ease, or explode with them—can give us information about our emotional appetite and how this may influence our physical appetite.
The science of appetite includes our habits with how frequently we eat, what time of day we eat, and how we substitute food for emotional or spiritual needs such as love or self-actualization. All of these contribute to the overall message we interpret from our guts to signal and symbolize the desire for food. Our bodies are designed to follow rhythms, such as circadian and ultradian, that help us anticipate routines for functioning. Much like our pets (or Pavlov’s dogs), we can get hungry simply because it’s noon and that’s what time we always eat lunch, whether our bodies perceive low blood sugar or not. The trick is to determine whether our habits are serving or inhibiting us.
Getting into habits that serve our nutritional, movement, and sleep needs can help our hypothalamus to optimally regulate metabolic functioning. Developing habits that tend to our emotional expressions can help us separate our appetite for food from our appetite for love, affection, and safety. And habits such as mindfulness, meditation, creative processes, or prayer can help feed our appetite for spirituality.
The Institute for the Psychology of Eating
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