Gut housekeeping: how to support your migrating motor complex

Most of us think about digestion only shortly after we eat or if we experience gastrointestinal symptoms, but our guts are busy clearing leftover food particles, waste, and bacteria long after a meal. This digestive tract housekeeping involves a pattern of cleansing waves called the migrating motor complex (MMC), and it requires a break from consuming things between meals. The MMC keeps our guts balanced and ready to process the next round of food.

Frequent snacking, late-night eating, and irregular meal spacing can sometimes lead to bloating, sluggish gut motility, intestinal bacterial overgrowth, feelings of never really being hungry, or a lack of effective cues that help us feel satisfied by food. Supporting the MMC with mindful meal, snack, and beverage timing can often help to alleviate these issues.

Did you know your gut has a built-in “street sweeper”? Give your digestive tract a break between meals to keep things running smoothly! #GutHealth #MMC #saslife
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What is the Migrating Motor Complex (MMC)?

You can think of the MMC as the street sweeper of the gut. The MMC is a repeating, cyclic motility pattern in the stomach and small intestine that occurs during the fasting state. This is different from the peristalsis that moves food and larger boluses of waste downstream. The MMC’s wave of gastrointestinal muscle contractions moves from the stomach toward the very end of the small intestine, helping sweep along bacteria, toxins, cellular debris, and other residue. The clean-up action of the MMC is essential for preventing an overgrowth of microbes in the small intestine. It happens in phases:

Phase I: quiet cleansing contractions
Phase II: building sweeping activity, somewhat irregular contractions
Phase III: the main MMC event

strongest, most propulsive cleansing waves

pyloric sphincter (valve at the bottom of the stomach) remains open allowing leftover undigested food particles to move on

Phase IV: transition back toward quiet

Why Meal Timing Matters

The MMC is a fasting-state pattern. When you eat, your gut switches from “housekeeping” mode to “digesting and absorbing” mode—so the MMC is interrupted by feeding. That means frequent grazing (even small snacks, flavored drinks, and gum chewing) has the potential to keep you in a near-constant fed state and may reduce how often you experience the stronger Phase III waves.

Hormones Behind the MMC: What Starts It and What Shuts It Down

The MMC is coordinated by a mix of gut hormones and nerve signals that helps your digestive tract toggle between two modes: a fasting-state cleansing pattern and a fed-state digestion pattern.

Hormones that Help Start the MMC (fasting state)

A host of hormones play a role in providing the “all clear” signal and getting the gut cleaned up between meals.

Motilin is the main timekeeper for MMC cycling. It’s released cyclically during the fasting state (about every 90–120 minutes) by endocrine cells in the beginning and middle of the small intestine and initiates the pathway leading to Phase III contractions that sweep residual material forward.

Ghrelin, produced mainly in the stomach, supports MMC activity and can enhance motilin-related effects, working with the vagus nerve to coordinate and propagate contractions during the fasting state.

Serotonin (5-HT) released from cells in the first part of the small intestine can help propagate MMC activity through 5-HT receptor pathways and it interacts with motilin in a positive feedback loop (i.e., 5-HT can stimulate motilin secretion, which can promote further 5-HT release).

Hormones that Suppress the MMC (fed state)

To prevent precious nutrients from being pushed through the digestive tract too quickly to be absorbed, the body orchestrates a selection of hormones that suppress the MMC when food comes through.

Somatostatin, released by cells in the stomach and the beginning of the small intestine, inhibits motilin release and suppresses cleansing GI contractions.

Cholecystokinin (CCK), released from cells in the beginning and middle of the small intestine after meals, promotes a fed-state motility pattern, prioritizing the appropriate movement of food along the digestive tract.

Other hormones that seem to have a role in promoting digestion and peristalsis of food and/or suppressing MMC activity include gastrin, insulin, glucagon-like peptide 1, secretin, peptide YY, and pancreatic polypeptide, shifting the gut away from fasting “housekeeping” and toward nutrient processing.

Simply put, when you eat, you trigger a hormonal “fed-state” signal that quiets the MMC. That’s why clear gaps between meals matter—those breaks give the MMC time to cycle and clean things up.

Spacing Meals to Support the MMC

Take food and beverage-free breaks between meals. Many clinicians suggest leaving roughly 3–4 hours between meals to give the MMC enough time for a complete, effective clean sweep. The ideal spacing can vary from person to person, depending on age, activity level, individual predispositions for gut motility speed, and medications that affect motility.

Be mindful of flavored and caloric beverages and gum. If the goal is a true between-meals break, fluids have the potential to alert the fed-state hormones.

Allowed: Water, black coffee, plain black or green teas

Avoid: Juice, soda, milk, sweetened beverages, coffee with cream and/or sweetener

Avoid eating a meal within 2-3 hours of bedtime. The body is less-efficient at digestion during sleep, and a poorly digested meal can interfere with the MMC.

Try to be consistent with meal timing. Drastic changes in the timing of meals can affect the circadian rhythm of the gut, potentially slowing gut motility and interfering with the MMC. For those beginning an intermittent fasting pattern, some time and consistency is often needed for the gut to adapt fully.

Meal timing can be a useful lever, but it’s not one-size-fits-all. If you do best with smaller, more frequent meals, don’t fear — the overnight fasting period counts too. A longer overnight break from eating allows for more gut sweeping cycles.

If you have a medical condition, a history of eating disorders, are pregnant, or have significant GI conditions, talk with a Registered Dietitian or other qualified clinician before making major changes to meal timing.

Though the MMC is stimulated by the absence of food, certain foods support gastrointestinal motility. Warm liquids relax the smooth muscle in the GI tract, making contractions and relaxation more rhythmic. Ginger stimulates serotonin receptors in the gut, which encourages gastric emptying and the rhythmic contractions of peristalsis. Soups containing ginger, like the one shown below, are a good way to support gut motility.

Tom Yum Seafood Soup

Serves 3-4
Recipe adapted from Gordon Ramsay
PRINT RECIPE

Though the MMC is stimulated by the absence of food, certain foods support gastrointestinal motility. Warm liquids relax the smooth muscle in the GI tract, making contractions and relaxation more rhythmic. Ginger stimulates serotonin receptors in the gut, which encourages gastric emptying and the rhythmic contractions of peristalsis.

Ingredients
4 cups water
⅓ cup Tom Yum paste or red Thai curry paste
10 oz package of frozen sliced mushrooms, thawed (or 8 oz button mushrooms, quartered)
2-3 lime leaves or 1-1 ½ tsp lime zest
2-3 sticks lemon grass, crushed
1-2 inch piece of ginger, cut into thin matchsticks
14 oz mixed seafood, preferably raw, defrosted if frozen
1-2 heads baby bok choy, chopped
dash of fish sauce
1 tsp - 1 Tbsp sugar, to taste
juice of ½ - 1 lime
cilantro, to serve

Instructions

Pour water into a pan and add the Tom Yum, or Thai curry paste, mushrooms, lime leaves, lemon grass, and ginger. Bring to a boil and simmer for about 5 minutes.

Add the seafood and chopped bok choy to the pan and cook for a few mins, until the prawns turn pink.

Add the fish sauce to the pan, then the sugar and lime juice to taste.

Remove lemon grass sticks and serve topped with cilantro.

Notes

⅓ cup of Tom Yum sauce is about a full 3.53 ounce jar.

After tasting, add extra lime juice and/or a dash of soy sauce, tamari or salt as needed to bring out the flavors.