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The Migrating Motor Complex (MMC) and Hunger

Updated: May 7


In this science post, we are continuing the conversation on digestion (who knew there was so much to discuss?) and will be exploring the fascinating function of our migrating motor complex (or MMC) and the concept of hunger.


Your stomach is “growling”. Is this a sign that you are hungry and need to eat?


Many of us growing up have learned to associate our stomach “growling” or noises coming from our abdomen with hunger and the need to eat. In fact, many of us feel the immediate need to take action and eat as soon as we receive these signals from our bodies. But does this mean we are hungry and we should eat? This is one of the most common questions that our members have when they begin the journey with The Livy Method, as they initiate the process of becoming more in tune with their bodies. 


So, why do our stomachs and abdomens make these noises, and how do we distinguish some of the things that our body does (like our stomach churning, rumbling and growling) with the actual need to eat? Is it because we are hungry?


Hunger


The feeling of “hunger” is fairly complex and can be affected by many things. Hunger can be influenced by physical/physiological, emotional, social, economic and mental factors and can be a difficult thing to gauge at times. 


Many of us lost touch with our hunger signals at a young age or were never really in tune with them in the first place. We may have become detached from understanding or recognizing these cues because of the influence of our family, social/economic factors, years of dieting and cycles of deprivation, over training and exercise, and eating when we are not hungry because we are following a set number of calories or macros determined by others in the diet industry. It’s no wonder we don’t know where to start. 


But not to worry. These signals are still there - and an imperative part of The Livy Method process is reconnecting our members with these very important signals that their body provides to them.


How can you get back in touch with your hunger signals?


Journaling and Self-Reflection


The Livy Method recommends journaling as a complement to The Program, as it can have a great benefit to the overall weight-loss process. This can also help identify any foods that have an impact on your digestion, as well as identify potential intolerances. 


Journaling your feelings/emotions and highlighting external factors, such as stress, exercise/activity and boredom can give you great insight into how your feelings, patterns or behaviours may influence you eating when not necessarily hungry. Using the traditional pen-to-paper process, or using the Livy Method App is a great way to do this. 


If you are the type of person who needs a more quantitative (quantitative data refers to any information that can be quantified, counted or measured and given a numerical value) way of understanding things, the use of a measurement tool such as a hunger scale may be of benefit to you. 


A hunger scale is a tool that can help you learn how to identify the difference between actual physical hunger and the “feeling” of hunger that may be brought on by emotions, like stress, boredom, sadness or happiness. 


Checking in and asking yourself the first two Mindfulness questions is a great way to assess this; but let’s take this a step further by using a hunger scale. 


Check out an example of a great hunger scale from Alberta Health Services. Some additional questions and considerations can help clarify the concept of eating to satisfaction.



Before you eat, ask yourself if you are hungry?


When serving or portioning out your food and before you eat ask yourself: How is this portion for me? How would I feel if I ate all of this?


When you start feeling like you want something to eat, rate your hunger on a scale of 1 to 10, with 1 being overwhelmingly hungry and 10 being so full you feel sick. A rating of 5 or 6 means you are comfortable, neither too hungry nor too full. When you feel hungry, especially after you recently finished eating, check to see if you are feeling a craving brought on by something psychological or emotional. The goal is to bring awareness to your changing hunger levels. For example, sometimes you are really hungry but then when you eat, you feel full fast. Other times you are not hungry at all, but when you start to eat, you feel hungry. Both are completely normal to experience. 


You may not get a really strong response or any answer from your body at first, but trust that once you begin this process of talking to yourself and taking the time to listen, your body will start to talk back.


While eating your food, pay attention to how you feel and ask yourself:


Am I getting full? Is this food satisfying me? How would I feel if I took a few more bites? How would I feel if I stopped eating now? Do I feel any physical effects of eating? On a scale of 1-10, how am I feeling, and where do I fall on that hunger scale?


When you are done eating, ask yourself how you feel:


Do you feel satisfied and if so, what is your definition of satisfaction? How do you know when you have eaten enough? How do you feel physically - energetic, comfortable, tired? Are you just eating everything on your plate because it is there? Or, maybe you feel like you could eat more? Again, you can rate how you feel on the scale from 1-10 to see where you fall with the goal being about a 5 or a 6. 


In terms of journaling and using the scale as a tool to assess satisfaction, reflecting on when and what you eat, as well as what you were doing and feeling before you started eating, can be really insightful in helping to identify psychological triggers for eating when you are not hungry. This may also help to identify habitual patterns of eating when you are not truly hungry. An example of this is wanting to eat a late-night snack while watching television because this is a nightly ritual that you indulge in in the evenings. 


Here are a few more tips for assessing hunger devised by the University of Michigan Medicine (Healthwise Staff 2020, September) that very much align with the philosophy of The Livy Method: 


  • Try not to let your hunger drop to a 1 or 2 on the hunger scale. When you get that hungry, you are likely to eat faster, make poorer food choices and keep eating past the “satisfied” point. 


  • On the other hand, let yourself feel some hunger between meals. Mild hunger is a good thing. After all, it’s a sign that you are not overeating. Teach yourself to appreciate hunger pangs as a natural part of life and as a sign that you are a healthy eater. 


  • Give cravings 10 minutes. When you suddenly feel the need to eat, tell yourself that you will wait 10 minutes. If it was only a craving, you will have forgotten about it by then and the urge will be gone. If 10 minutes go by and you still have the urge to eat, you may be starting to get hungry. Also, keep in mind, if you are craving something sweet, you may need more water, and if you are craving something salty, you may need more fat or salt. 


  • Don’t eat more now because you think you might not have time to eat later. Eat what your body needs now, and worry about later. 


  • Does leaving food on your plate bother you? Take smaller servings. Save leftovers for another meal. Share plates with someone. Ask yourself what is more important—a few bites of “wasted” food, or your health? This aligns with the Gina-ism, “your body is not a garbage can.” This is truly a very impactful statement when framing leaving food on your plate. 


  • When you eat, make your food the main attraction. Sit down at the table with your family. Do not eat in front of the television. Do not read or scroll on your phone while you eat. Give your attention to what you are putting in your mouth, how it tastes and how your body reacts to what and how much you are eating.


OK so after tuning in, you have determined that you are not “feeling” hungry and still have time before you could eat your next meal or snack. However, your stomach is rumbling…Should you still eat?


This is a great question, so let’s take a deeper dive into answering this.


Gastro Intestinal (GI) innervation and function


As discussed in The Basics of Digestion, our digestive system, from our esophagus to our anus, is made up of a special type of muscle called smooth muscle. Smooth muscle, which like other muscles in our body, contracts and relaxes. However, this mostly occurs automatically in our bodies without our conscious thought, although we do have some control over some aspects of it, such as the act of eating or having a bowel movement. 


See this video for more details about smooth muscle. 


Our digestive system is controlled by our central nervous system (CNS) and something called the enteric nervous system (ENS). These systems control our digestive processes primarily motility (a term used to describe the contraction of the muscles that mix and propel (move forward) the contents in the GI tract), the secretion of hormones and enzymes important to hunger, satiety and digestion, the absorption of nutrients in digestion and regulates blood flow to the digestive system. Our digestive system is often referred to as the “second brain” (containing as many neurons as the spinal cord) because of the amazing capabilities it has to perform many of these functions without consulting the brain. However, that being said, our digestive system is still influenced by the SNS (sympathetic nervous system) and the (PSNS) parasympathetic nervous system


Check out this great short video about the ENS.


Normal gastrointestinal motility results from the coordinated contractions of the smooth muscle in the digestive system. There are 2 fundamental patterns of movement conducted by the digestive system, propulsion and segmentation contractions. 


Propulsion is when the broken-down food (bolus) is propelled in a forward motion along the length of the digestive tube for the purpose of digestion and elimination (bowel movement). This movement is accomplished by peristalsis. In peristalsis, the smooth muscle contracts in a “ring” like form in front of the bolus (mouth side), propelling the bolus in the direction of the anus. The muscles on the opposite side of the bolus relax to allow the bolus to pass and occur until the bolus is broken down, absorbed and eliminated from the body. 


Check out this video to see what peristalsis looks like.


The majority of absorption occurs in the small intestine. For the purpose of optimal absorption, a movement involving mixing and a movement called segmentation, facilitates the combining of the ingested food with the secretions and enzymes needed for breaking down the carbohydrates, proteins and fats. These macronutrients are broken down into the smaller components needed to support body function, as well as allow for the extended time needed for absorption via the wall of the small intestine. 


In segmentation, the muscular rings of the smooth muscle alternate between a state of contraction and relaxation of the muscles along the wall of the intestines, which promotes the effective mixing of its contents. This movement is not meant to propel the contents forward. Segmentation’s primary role is for mixing and allowing the time needed for optimal absorption of nutrients, vitamins, and minerals at the bowel wall. 


Check out this video to see how segmentation facilitates absorption. https://www.youtube.com/ watch?v=ATXMxRPRPfU


What happens when the food we have eaten is digested?


The Migrating Motor Complex (MMC), Also known as the Migrating Motility Complex


The MMC is a distinct pattern of muscular activity observed in the gastrointestinal smooth muscle during the periods between eating, after most of the food that has been ingested has been digested. 


The MMC is often referred to as the “housekeeper” of the digestive system. These muscular contractions facilitate the movement or “sweeping” of any residual undigested material through the digestive system. 


Although the majority of our bacterial gut flora live in our colon or large intestine (which aid in digestion and promote the production of B vitamins and vitamin K), there is a small proportion of bacteria that do live in our small intestine. An important part of the MMC and its movement of undigested foods through our digestive tract is to prevent the proliferation or growth of these bacteria, which can lead to something called SIBO or small intestine bacterial overgrowth. So, the big takeaway here is that the MMC has a very important role in keeping us healthy and preventing the overgrowth of bacteria in our digestive system. 


The MMC also stimulates peristalsis, which is important in moving food through our digestive system and out of our bodies (by the way of bowel movements) but interestingly, the MMC is stimulated and only functions when we are not eating. 


The MMC is thought to be controlled by the CNS and elicited by the hormone motilin. The MMC is elicited when the body is in a “non-fed” state in a cycle that recurs every 1.5 to 2 hours and consists of four distinct phases or stages. When the body is ready to stimulate the MMC to initiate its “housekeeping” of the digestive tract, motilin is released from the upper portion of the small intestine. However, all that one needs to do to halt this process is to initiate eating again. 


Stage 1 is initiated by a quiet period with minimal muscular activity. There is only the occasional contraction occurring in the digestive system, lasting approximately 45-60 minutes. 


Stage 2 is about 30 minutes in duration. In this stage, peristalsis increases in intensity and occurrence. Peristalsis starts in the stomach and is directed towards the small intestine. 


Stage 3 is about 5-15 minutes in duration and is initiated by the occurrence of rapid, evenly-spaced peristaltic contractions. The pylorus (lower part of the stomach connecting to the duodenum of the small intestine) remains open during these peristaltic contractions, allowing indigestible materials to pass into the small intestine. This is in contrast to what occurs during the ingestion of food. 


After the completion of stage 3, there is a short period of time that elapses before these stages all begin again. This transition period is stage 4. 


Interestingly, while the MMC is activated, there is an increase in gastric, biliary, and pancreatic secretions seen with this contractile activity, which also likely assists in controlling the bacterial population in the upper segments of the digestive system. 


MYTH BUSTER- A growling stomach does not necessarily mean hunger it is likely the MMC in action.


As you can see, a “growling” stomach, especially after a meal, does not mean you are hungry. This is the stimulation of your very important MMC doing its very important job of cleaning out your digestive tract and keeping you healthy.


The Livy Method and how it promotes an optimal functioning MMC


  1. A healthy digestive system promotes a healthy MMC. The focus of The Livy Method is to improve and optimize digestion and absorption, and although the MMC is engaged in the periods we are not eating, they both go hand in hand. 

  2. Although we eat fairly frequently, at least 6 times a day, we still have up to 3.5 hours in between meals and snacks that allow for the MMC to engage. Because we are not eating to the point of being overly-full, and likely eating smaller amounts when eating to satisfaction, we are more likely to stimulate the MMC earlier than we might have in the past. Also, this is a means to an end in the pursuit of weight loss and change. Eventually, as we move into maintenance, we will not necessarily be eating this often unless it’s what our body needs. 

  3. The recommendation of eating our dinner earlier in the evening and minimizing late-night snacking is also in line with optimizing the role of the MMC. The body can focus on rest and repair and allow the MMC a good period of time overnight to do its thing. 

  4. The Livy Method promotes prioritizing restful sleep, self-care and stress management techniques that reduce cortisol levels and help keep hormones in homeostasis, preventing us from “stressing” our digestive system or impairing the function of the MMC. 


The following are a couple of videos that discuss digestion and the MMC in greater detail. 


This is a great video on motility. Discussion of the MMC starts at about 10:35 min of the video if you choose to skip ahead.


Hopefully, this post has given you more insight into the amazing MMC, the importance of digestion and how the foods we choose impact our health, the concept of hunger, and how using the tools and strategies discussed may help in assessing your hunger better.






References

Al-Missri, M., & Jialal, I. (2021, September 28). Physiology, motilin. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK545309/…

Betts, G.J., Young, K.A., Wise, J.A., Johnson, E., Poe, B., Kruse, D.H., Korol, O., Johnson, J.E., Womble, M., & DeSaix, P. (2019, May 29). Anatomy and physiology. Openstax. https://opentextbc.ca/anatomyandph.../chapter/smooth-muscle/

Cabrey, J., & Jakoi, E. (n.d.). Motility [Video]. Coursera. https://www.coursera.org/lecture/physiology/helpUrl-nUnNY

Costa, M., Brookes, S.J.H., & Henning, G.W. ( 2000). Anatomy and physiology of the enteric nervous system. Gut, 47(4), iv15-iv19. http://dx.doi.org/10.1136/gut.47.suppl_4.iv15

Deloose, E., & Tack, J. (2016). Redefining the functional roles of the gastrointestinal migrating motor complex and motilin in small bacterial overgrowth and hunger signaling. American Journal of Physiology, 310(4), 228-233. https://doi.org/10.1152/ajpgi.00212.2015

Deloose, E., Janssen, P., Depoortere, I., & Tack, J. (2012). The migrating motor complex: control mechanisms and its role in health and disease. Nature Reviews:Gastroenterology & Hepatology, 9(5), 271–285. https://doi.org/10.1038/nrgastro.2012.57

Electrophysiology of gastrointestinal smooth muscle. (n.d.). Vivo Pathophysiology. Retrieved March 30, 2022, from http://www.vivo.colostate.edu/.../basics/slowwaves.html

Gastrointestinal motility and smooth muscle. (n.d.). Vivo Pathophysiology. Retrieved March 30, 2022, from http://www.vivo.colostate.edu/.../basics/gi_motility.html

Gastrointestinal transit: How long does it take? (n.d.). Vivo Pathophysiology. Retrieved March 30, 2022, from http://www.vivo.colostate.edu/.../dig.../basics/transit.html

Gorard, D.A., Vesselinova-Jenkins, C.K., Libby, G.W., & Farthing, M. (1995). Migrating motor complex and sleep in health and irritable bowel syndrome. Digestive Diseases and Sciences, 40(11), 2383–2389. https://doi.org/10.1007/BF02063242

Grundy, D., & Brookes, S. (2011). Neural control of gastrointestinal function. Colloquium Series on Integrated Systems Physiology: From Molecule to Function, 3(9), 1-134. (https://doi.org/10.4199/C00048ED1V01Y201111ISP030)

Healthwise Staff. (2020, September 23). Healthy eating: Recognizing your hunger signals. University of Michigan Health: Michigan Medicine. https://www.uofmhealth.org/health-library/zx3292

How long does it take to digest food: Breaking down digestion speed. (2021, April 19). Cleveland Clinic. Retrieved March 30, 2022, from https://health.clevelandclinic.org/how-long-does-it-take.../

Hunger and fullness signals. (2021, March). Alberta Health Services. Retrieved March 30, 2022, from https://www.albertahealthservices.ca/.../if-nfs-hunger…

Nao. (2017, March 21). Why does my tummy rumble? Dr. How’s Science Wows. http://sciencewows.ie/blog/tag/migrating-motor-complex/

Takahashi, T. (2012). Mechanism of interdigestive migrating motor complex. Journal of Neurogastroenterology and Motility, 18(3), 246-257. https://doi.org/10.5056/jnm.2012.18.3.246

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Tomomasa, T., Morikawa, A., Sandler, R. H., Mansy, H. A., Koneko, H., Masahiko, T., Hyman, P. E., & Itoh, Z. (1999). Gastrointestinal sounds and migrating motor complex in fasted humans. The American Journal of Gastroenterology, 94(2), 374–381. https://doi.org/10.1111/j.1572-0241.1999.00862.x


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