Understanding Our Body as a System

Embodiment in Nutrition Counseling Series - Part 3

You eat a full lunch and twenty minutes later, you’re genuinely hungry again.

Your appetite disappears during the day, then shows back up the moment you finally sit down at night.

You finish a meal and don't remember eating it—it's just gone.

Food sounds good until it’s in front of you, and then suddenly nothing appeals.

These experiences can feel frustrating and confusing, almost like your appetite is working against you.

When we step back and look at the bigger picture, these patterns often start to make more sense. The body functions as an interconnected system, and changes in appetite are often signals about how that system is responding.

How your body systems talk to each other

Two communication networks help explain many of these patterns: the HPA axis, which manages your stress response, and the vagus nerve, which connects your brain and digestive system.

The HPA Axis: Your Stress Response System

Have you heard about the HPA axis?

It stands for hypothalamic–pituitary–adrenal axis, which is a mouthful. This is one of your body’s main communication networks, coordinating signals between your brain and your adrenal glands. It helps regulate hormones, energy use, and how your body allocates resources like glucose, oxygen, and blood flow throughout the day and in moments of stress.

Hoogendoorn, Claire & Roy, Juan & Gonzalez, Jeffrey. (2017). Shared Dysregulation of Homeostatic Brain-Body Pathways in Depression and Type 2 Diabetes. Current Diabetes Reports. 17. 10.1007/s11892-017-0923-y.

When stress increases, the HPA axis ramps up and cortisol, your primary stress hormone, rises. That cortisol shift can also change appetite‑related hormones like ghrelin, which tends to promote hunger and food seeking, and leptin, which reflects longer‑term energy stores and can help put some brakes on eating.

You might notice your appetite disappearing when you’re stressed, or you might suddenly crave comfort foods, or feel depleted despite eating more. Studies suggest that higher cortisol and changes in ghrelin and leptin are linked with comfort‑food eating, stronger cravings, or in some cases, a loss of interest in food after stress (Adam & Epel, 2007). The response varies: some people lose appetite almost entirely, others find themselves reaching for food more, and many move between these patterns over time. All of these are recognizable stress responses, shaped by your physiology, stress history, and relationship with food.

The Vagus Nerve and Your Nervous System States

Your gut and brain are also in constant conversation through the vagus nerve, the longest nerve in the body. It carries messages in both directions between your brain and organs, including our digestive system. Here's the part that surprised me when I first learned it: about 80% of those signals travel from your body to your brain. In other words, your body has a lot to say! That ongoing traffic influences digestion, mood, immune responses, and how you handle stress and emotions (Cryan & Dinan, 2012).

The vagus nerve is also part of how your nervous system shifts between different states throughout the day. You might recognize some of these:

Rest and digest: When you feel safe and relatively calm, ventral vagal pathways support smoother digestion. You can taste your food, notice more subtle hunger and fullness cues, and feel your body settling. This is when your body can more easily absorb nutrients and send clear signals about what it needs.

You know this feeling: sinking into the couch at the end of the day. An exhale. Perhaps this feels rare with our modern pressures. We have the news cycle, social media, economic stress, the mental load of schedules and tasks, diet culture's constant noise. Sometimes it means actively reducing stimulation: turning off your phone, stepping outside, breathing slowly, or getting support that helps your body regulate, whether that's body-based (massage, yin/restorative yoga, acupuncture), mind-based (therapy, coaching), or relational (a friend who truly gets it).

Fight or flight: When you’re stressed, anxious, or perceiving threat, sympathetic activation takes the lead and your body prioritizes survival. Digestion can slow or pause, blood flow shifts away from the gut, and appetite may drop or feel “jittery” and unreliable. You might know you need to eat but feel unable to because your body is focused on immediate safety, not processing lunch.

Think about how you feel before public speaking: heart pounding, water bottle glued to your hand (SO thirsty!), running to the bathroom every five minutes, abdomen alive with sensation, but zero room for food. Or the lower-grade version with chronic stress: morning appetite destroyed by an early alarm and a chaotic commute, relying on coffee to function, appetite finally showing up at night when you're trying to wind down.

Freeze or shutdown: In overwhelming or prolonged stress, dorsal vagal pathways can dominate and you may feel numb or disconnected. Hunger and fullness cues become muted or distant. You might go hours without noticing you haven’t eaten, or eat on autopilot without much satisfaction.

Everything feels slow as molasses. Your body demands stillness. Food decisions feel impossible, and honestly, you don't really care what you eat as long as it's easy. Drive-through Dunkin' wins over making lunch. Not because you don't "value your health," but because your nervous system is conserving every bit of energy it has left. Caring requires capacity.

This framework is called Polyvagal Theory (Porges, 2011), and it offers language for why nervous system state matters so much for embodied eating. When your system is in a safer, more regulated state, it’s easier notice our body signals. When it's activated or shut down, those signals become harder to access.

What I'm noticing

Right now, most clients I work with are managing some form of chronic stress. It's the accumulated stress of work demands, family dynamics, relationship strain, financial pressure, physical illness, sleep disruption, and the constant pull of screens and information. Diet culture adds its own layer with the constant pressure to meet narrow standards of appearance and wellness. Add political uncertainty, threats to safety and rights, and ongoing exposure to crisis. Your stress response, which is designed for short-term threats, is running continuously.

Your body feels all the stress, regardless of the source. Stress changes appetite, digestion, and food choices. It can suppress hunger or intensify cravings. For many people, food becomes a means of comfort, distraction, or regulation when other resources feel depleted.

When we look at eating patterns through the body's stress response systems, they start to make sense.

Eating lunch and feeling hungry twenty minutes later? This could be about nervous system state during eating, inadequate intake over previous days, and/or needing more food than that meal provided.

Your appetite disappearing when stressed, then roaring back at night? This could reflect fight-or-flight suppressing appetite during the day, under-eating that your body compensates for later, and/or finally feeling safe enough to eat once you slow down.

You finish a meal and realize you don't remember eating it? This could reflect eating in survival mode, multitasking during the meal, and/or dissociation preventing presence with food.

Food sounding good until it's in front of you, then suddenly nothing appeals? This might reflect a shift in nervous system state, blood sugar dropping while you waited, and/or realizing the food doesn't match your actual needs.

In summary, your body is adaptive and protective, working hard to carry you through. Understanding it as an interconnected system including the HPA axis, vagus nerve, and different nervous system states, helps you step back, notice what state you're in, and choose supports that meet you where you are at.

References

Adam, T. C., & Epel, E. S. (2007). Stress, eating, and the reward system. Physiology & Behavior, 91(4), 449–458.

Cryan, J. F., & Dinan, T. G. (2012). Mind-altering microorganisms: The impact of the gut microbiota on brain and behaviour. Nature Reviews Neuroscience, 13(10), 701–712.

Porges, S. W. (2011). The Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-Regulation.