Intermittent Fasting and Gut Health
What is intermittent fasting?
Intermittent fasting or time restricted eating is when we do not eat for an extended period. There are different variations, the most popular and easy to do is 12/12 (12 hours fast, 12 hours feeding). The one I prefer and the one that has the most benefits is 16/8 (16 hours fast, 8 hours feeding).
There is also alternate day fasting and prolonged fasting (24-36 hours).
At 16 hours of not consuming food, the body turns on a process called autophagy that cleans damaged cells and repairs tissues. Therefor reaching 16 hours without food is very beneficial for the body.
There is another very important process that gets turned on 90 minutes after we stop eating or during fasting, the so-called Migrating Motor Complex or MMC. This is basically a wave like motion of the intestines that sweep away any left over food, bacteria and pathogens. Therefore, constant snacking is a bad idea, because we are not giving the chance of the digestive system to clean itself up. Hunger stimulates the release of hunger hormones like Ghrelin which stimulate the MMC. A proper functioning MMC also prevents bacteria to colonize in the wrong place and to cause something called SIBO (Small Intestinal Bacterial Overgrowth).
How about the microbiome?
Research shows that fasting improves the growth of certain beneficial bacteria like Akkermansia mucinophila and Bacteroides fragiles. These two species improve the health of the intestinal barrier and prevent the so-called leaky gut. Compromised intestinal barrier can lead to a number of health issues like autoimmunity, food allergies and intolerances, joint pain, low grade chronic inflammation.
And that is not all. The very important microbiome marker Firmicutes:Bacteroides ratio improves with long periods of fasting. Obesity and metabolic disorder have been linked to not having an optimal ratio.
The cells of the intestinal epithelium are being replaced every 4 days because of the enormous wear and tear caused by the passage of food. Giving longer rest to your digestive tract will help the repair and the proper regeneration of the mucous layer which is where many beneficial bacteria live and feed off from. These beneficial bacteria produce a byproduct, a short chain fatty acid, called butyrate. It serves as food to other bacteria as well as it helps mentan the health of the gut barrier and mucous layer. It has also an important anti-inflammatory role in the gut. Research shows that intermittent fasting increases butyrate.
How to incorporate intermittent fasting into your life?
Start by having at least 12 hours between meals overnight. Then increase the fasting window by one hour, for example dinner at 7pm and breakfast at 8am. Add and extra hour every few days until you reach 16 hours of fasting. It is not necessary to do this every day. In fact, variations of this are very beneficial. This creates the so-called metabolic flexibility which is another marker of good health.
Have a balanced lunch with good fats, protein and fiber that will keep you full until dinner. If necessary, you can have a small snack of some nuts but not sooner than 3 hours after you have finished your meal.
If you are curious about the beneficial bacteria we just mentioned and whether you have proper balanced microbiome, an extensive stool test analysis can help to really pinpoint any problems. Read more about stool testing here.
