You probably think about what you eat and when you eat, but do you know what your gut is doing when you aren’t eating? Well, today you’re going to learn why that window of time might be one of the most important factors in your digestive health!
Meet the migrating motor complex. It’s one of the most fascinating and under appreciated systems in your body.

What Is the Migrating Motor Complex?

The migrating motor complex — or MMC — is a series of electrical waves that sweep through your digestive tract during periods of fasting. You can think of it as your gut’s built-in cleaning crew. It starts in your stomach, moves through the small intestine, and sweeps everything forward — leftover food particles, dead cells, mucus, and bacteria — and out of the small intestine.
Without your MMC, things start to accumulate that shouldn’t (more on this shortly).
And the MMC only activates when you’re in a fasted state. Once you eat (or drink something caloric), your MMC shuts off and your body shifts into digestive mode. 

Why This Matters for Your Health

Your small intestine is supposed to be relatively low in bacteria compared to your large intestine. The MMC is one of the primary reasons for that. By regularly sweeping bacteria forward and out, it helps maintain the balance of bacteria in your small intestine, supporting proper function.
When the MMC is disrupted or sluggish, bacteria can begin to accumulate in the small intestine where they don’t belong. This is one of the leading proposed mechanisms that can lead to SIBO (small intestinal bacterial overgrowth). SIBO is one of the root causes of bloating, gas, irregular bowel movements, and even nutrient malabsorption.
And importantly, research has found that people with conditions that impair gut motility — including diabetes, hypothyroidism, and certain autoimmune conditions — often have compromised MMC function, and a corresponding higher risk of SIBO. These connections between the MMC and SIBO are important to understand, especially if you want to resolve  (or prevent) digestive issues.

What Disrupts Your MMC?

Your current eating habits could either be helping or hurting your MMC and digestive health. Here are some big MMC disruptors:

• Frequent snacking. This is the big one. Every time you eat, you reset the MMC cycle. If you’re grazing throughout the day — even on healthy foods — your gut’s cleaning cycle never gets a chance to complete. The MMC starts 90 mins-2 hrs after you finish eating and needs roughly 90 mins-3.5 hrs to run a full sweep.
• Chronic stress. Your nervous system plays a direct role in MMC function, and the connection is more profound than we thought. The MMC is coordinated by your enteric nervous system (a whole network of neurons in your gut wall, also called your “second brain”), your brain, and your vagus nerve. In a calm, parasympathetic state, this communication works well and your MMC runs on schedule. When you’re under chronic stress, it’s a different story: Your body is operating in a low-grade sympathetic (“fight or flight”) state almost continuously. In that mode, your brain is signaling to your body that survival takes priority over housekeeping. Digestion and motility get deprioritized. The hormone motilin — which is the primary trigger for MMC contractions — is sensitive to this shift. Elevated cortisol (our primary stress hormone) can suppress motilin release and blunt the strength of your MMC waves. Not good. But another layer to this is that chronic stress also increases intestinal permeability (aka leaky gut) and promotes low-grade gut inflammation. An inflamed gut lining is a sluggish gut lining. So stress isn’t just suppressing the signal to clean house — it’s also impairing the machinery doing the cleaning. Over time, this creates exactly the kind of environment where bacteria accumulate in the small intestine and digestive issues develop.
• Poor sleep. MMC activity is closely tied to your circadian rhythm. Research suggests that MMC function is more robust during nighttime hours, which is one of the reasons an overnight fast is so valuable for gut health — your body is doing some of its best housekeeping while you sleep (at night). If you go to bed late or skimp on sleep, you aren’t giving your MMC the opportunity to do as thorough of a cleaning.
• Low stomach acid. This one tends to surprise people, because we rarely think of stomach acid as having a role beyond breaking down food in the stomach itself. But stomach acid — hydrochloric acid, or HCl — is a massively important signal that coordinates all of our downstream digestion, including MMC function. Here’s how the sequence is supposed to work: when food arrives in your stomach, HCl drops the pH significantly, activating the enzyme pepsin to begin protein digestion. That acidic environment then triggers the release of a hormone called secretin from the lining of your small intestine (secretin is what signals your pancreas to release bicarbonate and digestive enzymes, signals the gallbladder to release bile, and also plays a role in coordinating gut motility). When stomach acid is low, the pH of the stomach contents entering the small intestine isn’t acidic enough to trigger a robust secretin response. So, your enzyme and bile output are reduced, your food is less thoroughly broken down, which means larger, partially digested particles are moving through your small intestine — exactly the kind of environment that feeds opportunistic bacteria and sets the stage for SIBO and fermentation-driven symptoms like bloating and gas. And guess what? Motilin, the hormone most directly responsible for initiating MMC contractions, also needs proper acidification! So low HCL is going to lead to weaker and less frequent MMC contractions (less cleaning). That’s a bad combo: more opportunistic bacteria building up and less clearing of it out. 
  • Certain medications. Opioids are well known to significantly impair gut motility; GLP-1 meds interfere with proper MMC function; PPIs (proton pump inhibitors) used long-term to suppress stomach acid may also play a role.

What Supports Your MMC?

The good news is that there’s a lot you can do to support this system — and most of it is pretty simple.

• Give yourself real gaps between meals. Aim for 3.5- 4.5 hours between eating meals/snacks to allow your MMC to complete a full cycle. 
• Don’t eat within 2 to 3 hours of bed. Your overnight fast is prime MMC time. 
• Prioritize sleep quality. Since MMC function follows your circadian rhythm, protecting your sleep is also protecting your gut motility. 
• Actively manage stress. Stress management tools show up in almost every conversation about gut health. Your vagus nerve plays a central role in coordinating gut motility, and chronic stress dampens vagal tone. Breathwork, gentle movement, and even humming (as we explored in a previous newsletter) all support the parasympathetic state your gut needs to do its cleaning.
• Consider ginger. Ginger has been studied for its prokinetic properties — meaning it supports the forward movement of contents through the digestive tract. A cup of ginger tea between meals is a simple, gentle way to support motility.
• Stay hydrated between meals. Water (without calories) does not disrupt your MMC: it helps it by keeping things moving.

The Bigger Picture

Your MMC is an amazing system that cleans your gut and amplifies your health and now you know what to do (and not do) to support it to function optimally.
If you’ve been dealing with persistent bloating, feeling full long after meals, or digestive symptoms that don’t seem to respond to dietary changes alone, the tools for supporting your MMC could make a big difference.
Sometimes the most powerful thing you can do for your gut health isn’t adding something to your plate: It’s stepping away from it.

As a functional nutritionist, I don’t just help you to eat healthier: I help you create a healthier lifestyle.  

If you’re ready to discover where your best health has been hiding, I’d love to connect with you!

Apply for a complimentary Unstoppable Health Discovery Session.  http://bit.ly/schedulinghealth (subject to availability).

Until next time, wishing you unstoppable health,

~Rebecca

 
As always, nothing in this newsletter is intended as medical advice. Please work with a qualified healthcare provider before making changes to any medications or treatment plans.