December 1, 2016

Digestion 101: Why we Don’t Eat Before Yoga & Exercise.

Christy Mckenna/Flickr

Do you think about eating?

I think about food from the moment I wake up. Often, finishing one meal, I’m thinking about the next.

Does that sound familiar? I know I’m not the only one obsessed with food.

A student (obsessed with eating, like me) asked last week, “Why don’t we eat before a yoga class or drink water during class?”

“Water puts out the internal fire,” I said with a head bobble.

I’m sure you’ve heard this answer before. It wasn’t the first time I’d given this answer. It’s the answer taught me by my teacher and the answer that was given by their teacher.

But the student wasn’t satisfied. I wasn’t either.

I don’t talk in prana or chakras or bhava. (I’m not even sure I spelled bhava correctly!)

They wanted more. They wanted the why. They wanted the heart. So I started to go into it. I’m a nurse when I’m not teaching people around the world how to touch their toes. Part of what nurses do is patient education. We take the big complex science and make it digestible and understandable. A translator, if you will.

I looked around online for some direction to point them. Mind Body Green listed foods to eat before yoga; Eat This was basically the same article. Ace Fitness, Huffington Post, Shape and Men’s Health all listed the worst things to eat before working out—foods to avoid, diet rules backed by science.

None of it explained *why*. So I tried to explain to my students…

Have you ever gotten a cramp during a run?

Muscles used for peristalsis (the movement of food along the intestinal tract) are locking down trapping food that produces gas.

When running, our heart can’t keep the necessary blood volume up to digest food and give blood to the muscles, and thus engages in a fight-or-flight response.

The primitive part of the brain takes over and shuts down the entire GI system. All secondary functions like digestion are halted so that we can get away. The brain thinks it’s being chased by an animal and going to die.

Navasana is a beast! It wants to eat you.

She began to understand.

That was the simple explanation. Beyond the simple, it puts out the prana.

Do you want more? What follows is Digestion 101 in about three minutes—without the complicated parts and exams.

Once we swallow, digestion becomes involuntary. The Autonomic Nervous System (ANS) controls this for us automatically.

Think, Autonomic is Automatic.

This means we don’t have to think about which hormones and enzymes need to be released or about peristalsis (muscle movement of food) in the gastrointestinal tract. Leaving us more time to focus our attention on more important matters like double tapping a photo on Instagram or a recipe on Pinterest.

Digestion happens when the body is at rest and not running from the belly of a beast. Or wishing the count was a little faster in navasana.

The ANS works on the unconscious control of systems (i.e. digestion, heart rate, respiratory rate, pupil dilation, urination and sexual arousal).

Yes, sexual arousal is automatic. But this is about digestion. Focus.

Because we are unconsciously operating these systems, the body has divided them into two groups. The ones that need immediate attention go into the sympathetic system. These are the systems that function in a fight-or-flight scenario—like being chased by a Navasana or a Marichasana D—these guys take precedence.

The other system, the parasympathetic system, is for the things that don’t require an immediate response. These guys are in use while we’re resting. Like digestion.

The body likes to stay in balance. The two systems, sympathetic and parasympathetic, function in opposition to each other.

Homeostasis. (That big word from High School Biology)

The heart, the thing in the middle of your chest that teachers like to ask you to open, likes to have blood. In order to do so, it needs to maintain a certain pressure during activities. It relays a message back to the brain constantly letting it know where to direct the blood.

During activities such as running, yoga, surfing and biking, our fight-or-flight system takes control. The body demands more blood for the muscles and lungs (sometimes as much as 1,200 percent). To get the blood volume to these organs the body diverts blood away from the gastrointestinal tract and skin. Around that time, our heart rate increases and peristalsis decreases.

Remember that fabulous Raw Mexican Lasagna you had before coming to class?

The stomach has two ring-like muscles that lock in food for hours, mixing it with acids to target bacteria as well as enzymes to process fats and proteins. It typically takes about two to three-and-a-half hours before the stomach empties 50 percent of its contents into the intestine for further incorporation into the body. But it only does this when the body is at rest.

That’s why it is recommended to not eat one to two hours before a yoga class or engaging in physical activity.

Eating before a yoga class gives the brain mixed messages.

During digestion, the vagus nerve is trying to take control over the parasympathetic system asking for blood to the GI tract because of the metabolic demand of the gut.

But you are in a yoga class twisting your body, standing on one leg, bending over backward, trying to get your leg behind you head. Essentially running from the beast—or fighting it. You are a warrior after all!

Except your mind and body are freaking out.

Practice is hard enough. Why make it more difficult?

Ashtanga Nurse Rx:

  • Drink a cup of coffee (hot water and lemon is a substitute) one hour before practice in the morning.
  • If taking practice in the afternoon eat nothing one to two hours beforehand. Allow 30 minutes after practice before consuming food. Talk with your teacher about dealing with low blood sugar or if feeling faint. Possibly, try eating a banana, as they are easily digestible.
  • No coffee, no prana. (Coffee stimulates peristalsis and aides with defecation, elimination of waste.) Give the body time to stabilize the blood volume and recover from the fight-or-flight response.


Author: Morgan Lee

Image: Christy Mckenna/Flickr

Apprentice Editor: Lois Person; Editor: Toby Israel


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