Root causes and contributors to IPS and RH
Idiopathic postprandial syndrome describes people who have the symptoms of hypoglycemia without lab confirmed low blood sugar. The body feels as if it is dropping, even though the numbers do not fully match. The roots of this pattern are often in the nervous system, the gut brain axis, and subtle metabolic stress.
Post viral or infectious nervous system changes
Viruses such as Epstein Barr, COVID, and other infections can sensitize the autonomic nervous system. Afterward, normal sensations from the gut, heart, and blood vessels can be misread as dangerous. Many people describe that their crashes began after an illness, even if lab values now look stable.
Chronic stress and trauma
Long periods of stress can keep the body in a state of heightened arousal. The brainstem and vagus nerve become tuned to watch for danger inside the body. When blood sugar rises and then falls, even within a normal range, the body may respond with adrenaline as if something is wrong. Over time, this can create a pattern of false low sensations.
Low carb or extreme dieting history
Very low carbohydrate diets can reduce glycogen stores and force the body to rely on alternative fuel pathways. For some sensitive people, this can strain mitochondria and create post exertional fatigue, fragile energy, and a nervous system that reacts strongly to carbohydrates once they are reintroduced. This can feel like a blood sugar problem even when numbers are technically normal.
Gut inflammation and vagus nerve sensitization
Irritated or inflamed gut tissue sends stronger signals to the brain. The vagus nerve is the main communication pathway. When the gut is unsettled, stretched quickly, or exposed to certain foods, the vagus nerve can send alarm signals upward that feel like dropping, nausea, dizziness, or panic. These sensations can mimic hypoglycemia and often appear shortly after eating.
Autonomic nervous system dysregulation
Conditions like postural orthostatic tachycardia syndrome and other forms of dysautonomia can make the body very sensitive to shifts in blood flow, heart rate, and digestion. Standing, eating, or even slight changes in blood volume can create intense physical sensations. These can overlap with or be mistaken for blood sugar swings.
Rapid glucose swings within the normal range
Even when numbers never fall into official hypoglycemia, a quick jump up and then a noticeable drop can feel like a crash to a sensitive nervous system. The body responds more to the speed and direction of change than the exact number itself. This is why some people feel symptoms at levels that are technically normal.
Caffeine, nicotine, and stimulants
Stimulants can increase baseline adrenaline and make internal sensations louder. When combined with fragile glucose regulation or nervous system sensitivity, they can worsen post meal symptoms or trigger episodes.
Electrolyte imbalance and low blood volume
Low sodium intake, dehydration, or low overall blood volume can worsen dizziness, lightheadedness, and fatigue after meals. The body shifts blood flow to the gut for digestion, and if volume is already low, this can feel like a dramatic internal drop.
Sleep deprivation and circadian disruption
Poor or fragmented sleep makes the nervous system more reactive and reduces the body’s capacity to handle ordinary stressors. Blood sugar regulation becomes less precise, cortisol rhythms shift, and the threshold for symptoms lowers.
Perimenopause and hormone shifts
Fluctuations in estrogen and progesterone can influence both insulin sensitivity and nervous system reactivity. Some people notice that post meal symptoms flare during certain phases of their cycle or during perimenopause.
Shared themes beneath both IPS and reactive hypoglycemia
Even though one group has true low numbers and the other does not, there are common threads that run through both experiences.
First, there is often a history of pushing the body hard. This can be through chronic stress, caregiving, grief, illness, over exercising, under eating, or perfectionistic self pressure. Second, there is often a moment or period where something shifts. For some, it is an illness. For others, a new diet. For others, a traumatic event or a period of intense anxiety. Third, the nervous system begins to over protect. It starts reacting strongly to internal change. A slight dip in blood sugar, a full stomach, or a normal digestive wave can suddenly feel enormous and frightening.
The fourth common thread is that people are often told that nothing is wrong. Because tests are limited and research is still developing, many are told that their experience is simply anxiety or stress. This can create shame on top of physical suffering. In reality, what is happening is a complex interaction between metabolism, the nervous system, hormones, and lived experience. It is real, even if it does not yet have a tidy label.
Why understanding root causes brings hope
Knowing the possible roots does not mean you have to identify every single one in your own story. It does mean you can begin to see your experience in context. You can recognize that your body is not random. It is responding to years of input, strain, and adaptation. When you see this, you can approach healing with more compassion and less blame.
Instead of thinking your body is failing, you can begin to see it as a system that has been overprotecting you. Instead of wondering if you are imagining your symptoms, you can recognize that they have plausible, understandable origins. This opens the door to layered healing. You can address nutrition, nervous system regulation, sleep, stress, movement, and medical evaluation in a way that feels coherent rather than scattered.
Research is still catching up. Many of these root causes are being described first in communities and forums, long before they are fully mapped in journals. That does not make them less real. It simply means that people like you are on the frontier of understanding. Your story matters. Your patterns hold wisdom. And slowly, step by step, both your body and the science will move toward greater clarity.
If you see yourself in any of these root causes, know this. You are not alone. You are not broken. You are living inside a system that has been through a lot. With steady support, it can relearn safety. It can become less reactive. It can move away from constant crisis and toward steadiness after eating.