Why does stress affect digestion so quickly?
Your autonomic nervous system has two main gears: the sympathetic state (fight or flight) and the parasympathetic state (rest and digest). When you perceive a threat — whether it is a physical danger or just an overwhelming email inbox — your sympathetic nervous system takes over.
In this state, your body assumes you need energy for survival. It immediately diverts blood flow away from the digestive organs and routes it toward your muscles and brain. The production of stomach acid decreases, and the muscular contractions that move food through your intestines slow down or stop completely. If you eat while stressed, your body is simply not equipped to process the nourishment.
What is the vagus nerve's role?
The vagus nerve is the primary physical connection between the brain and the gut. It acts as a two-way communication highway. Interestingly, about 80% of the signals travel from the gut up to the brain, not the other way around. This means the state of your digestion directly influences your mood and anxiety levels.
When the vagus nerve is functioning well (high vagal tone), it tells the stomach to churn, the gallbladder to release bile, and the intestines to absorb nutrients. When vagal tone is low due to chronic stress or trauma, the entire digestive sequence becomes sluggish, leading to symptoms like bloating, indigestion, and constipation.
"If you look after the root of the tree, the fragrance and flowering will come by itself. If you look after the body, the fragrance of the mind and spirit will come of itself." — B.K.S. Iyengar, Yoga: The Iyengar Way
How does therapeutic yoga restore the connection?
"We address the gut-brain connection, which plays into digestive issues. We soften the belly and calm the nervous system — the breath calms the nervous system, which allows the digestive system to function." — Tiffany Bergin, C-IAYT, CIYT
In Iyengar yoga, we do not separate the physical organs from the nervous system. We work with them simultaneously. When treating digestive issues, a yoga therapist looks at both mechanical stimulation and nervous system regulation.
Mechanically, twisting poses like Bharadvajasana and Marichyasana physically compress and release the abdominal organs. This "squeeze and soak" action brings fresh blood flow to the digestive tract and stimulates the liver and kidneys.
Neurologically, forward extensions (like Paschimottanasana) and supported inversions (like Viparita Karani) calm the brain and stimulate the parasympathetic nervous system. As B.K.S. Iyengar notes in Yoga: The Path to Holistic Health, these poses quiet the sympathetic drive, signaling to the body that it is safe to return to "rest and digest" mode.
Why diet changes aren't always enough
As a functional nutrition & lifestyle educator, I often see clients who have eliminated gluten, dairy, and sugar, yet still experience digestive pain. The food is not the problem — the environment the food is entering is the problem. If your nervous system is dysregulated, even the cleanest, most organic meal will be difficult to digest.
This is why an integrative approach matters. We use functional nutrition to identify what nourishes you, and therapeutic yoga to ensure your body is actually in a state to receive it.