How Intermittent Fasting Can Transform Your Gut Microbiome

Of all the health trends gaining traction, intermittent fasting takes the cake. It’s touted as a powerful tool for everything from weight loss to longevity. But here’s the thing: it doesn’t work for everyone. Particularly if you have a complicated relationship with food. On the flip side, this trendy eating pattern could be the secret weapon for revolutionizing your digestion. And—by extension—improve your overall well-being. Sound too good to be true? We’re getting to the heart (err, gut) of the matter. Scroll to connect the dots between intermittent fasting and gut health. It’s time to align your eating patterns with your body’s natural rhythms.

Edie Horstman

Edie is the founder of nutrition coaching business, Wellness with Edie. With her background and expertise, she specializes in women’s health, including fertility, hormone balance, and postpartum wellness.

What is intermittent fasting?

Before we dig into all things gut health, let’s talk about intermittent fasting. IF isn’t about what you eat, but when you eat. It involves cycling between periods of eating and fasting. Common approaches include:

• The 12/12 method: Fast for 12 hours and eat during a 12-hour window, i.e., eating between 7 a.m. and 7 p.m., then wait to eat until 7 a.m. the next day. For beginners, this is ideal—as a majority of the fasting is during sleep.
• The 16/8 method: Fasting for 16 hours and eating within an eight-hour window, daily.
• The 5:2 diet: Eating normally for five days and drastically reducing calorie intake for two non-consecutive days.

These fasting periods can significantly help your digestion and metabolism (so the research indicates). During fasting, your body shifts into a state of rest and repair, allowing your digestive system to recuperate and reset.

A (Gender) Data Gap

While intermittent fasting is well-researched, studies on women are limited. As it stands, much of the existing research is conducted on men (or animal models). Why is female-centric research less abundant? Largely because we have a more complex hormonal system compared to men. This system is especially sensitive to changes in energy balance—such as those induced by fasting. For instance, fasting influences reproductive hormones like estrogen and progesterone, which affects menstrual cycles, fertility, and overall hormonal balance.

Who benefits from intermittent fasting?

If your wellness goals include weight management, improved metabolic health, or reduced inflammation, give IF a shot. But bear in mind: it’s not a one-size-fits-all approach. Consider your unique hormonal needs, life stage (i.e., are you trying to conceive?), and intentions before diving in.

1. Women with PCOS and/or insulin resistance:
   • Intermittent fasting can help improve insulin sensitivity and support weight loss, which may be beneficial for women with metabolic syndrome or PCOS.
2. Women with a healthy body weight and regular menstrual cycles:
   • For those not trying to conceive and have a stable hormonal profile (you don’t have hypothalamic amenorrhea), IF may offer benefits like better mental clarity and energy levels.
3. Women seeking general health benefits:
   • So long as you don’t have any specific hormonal/reproductive concerns, you may find that a moderate and flexible approach to IF will improve overall biomarkers, like sleep and digestion.

Who might not benefit from intermittent fasting?

Conversely, if you’re currently pursuing intuitive eating, balancing your hormones, or conceiving, IF may not support your well-being goals.

1. Women who are pregnant/trying to get pregnant:
   • IF is generally not recommended during pregnancy or when actively trying to get pregnant, as the energy demands are higher. Your focus should be on nourishing your body to support a healthy pregnancy!
2. Breastfeeding women:
   • Breastfeeding requires additional calories and nutrients. Restricting food intake—through IF—could potentially impact milk supply and energy levels.
3. Women with low body fat or a history of eating disorders:
   • Women with low body fat and/or those who have struggled with disordered eating should approach IF with caution. Unfortunately, it can exacerbate underlying issues or lead to nutrient deficiencies.
4. Women who engage in intense exercise:
   • Love high-intensity exercise? Or are you training for a triathlon, half-marathon, or marathon? IF might not provide enough fuel for optimal performance and recovery, leading to fatigue or increased injury risk.

The Gut Microbiome: What You Need to Know

Switching gears, let’s talk about the gut microbiome. This complex ecosystem plays a crucial role in your health. These tiny tenets influence just about everything: your immune function, mood, metabolism, and how well you absorb nutrients. Unfortunately, this delicate ecosystem is easily disrupted by factors like diet and stress. As a whole, maintaining a healthy, diverse gut microbiome is essential for:

• Strengthening your immune system
• Regulating inflammation
• Improving mental health
• Enhancing digestion and nutrient absorption

How Intermittent Fasting May Benefit Gut Health

Can the simple act of timing your meals improve your gut health? Here’s what we know:

It can reduce inflammation

Fasting periods may help decrease gut inflammation, creating a more hospitable environment for beneficial bacteria.

It can increase microbial diversity

Studies show that IF can promote a more diverse gut microbiome, which is associated with better overall health.

It can help repair your gut lining

Fasting gives your gut lining a chance to repair and regenerate, potentially reducing issues like leaky gut syndrome.

A 2019 study found that time-restricted feeding led to positive changes in the gut microbiome of mice—even when they consumed a high-fat diet. While more human studies are needed, these results are promising!

Taking a Closer Look at Time-Restricted Eating

Time-restricted eating (TRE) is a form of intermittent fasting that involves limiting your daily eating window. Meaning, you consume all of your daily calories within 8-12 hours. This approach aligns with the body’s natural circadian rhythms and may offer specific benefits for gut health:

• Encourages the growth of bacteria that thrive on a consistent feeding schedule.
• Promotes healthy gut movement and digestion.
• Strengthens the gut lining, reducing the risk of harmful substances leaking into the bloodstream.

Fermented Foods for Gut Health

Want to take things one step further? While intermittent fasting sets the stage for a healthier gut, incorporating fermented foods further amplifies these benefits. Fermented foods are rich in probiotics—live beneficial bacteria that can help balance your gut microbiome. As a natural complement to IF, fermented ingredients introduce diverse strains (the goal!) and can help repopulate your gut during eating windows.

Fermented Foods List: Top Picks for a Healthier Gut

Here’s a list of gut-friendly fermented foods to incorporate into your diet:

Yogurt: Rich in probiotics, especially when it contains live active cultures. Break your fast with these spicy Turkish eggs over yogurt!

Kefir: A fermented milk drink with a diverse range of beneficial bacteria. This blueberry smoothie packs a healthy dose of kefir for a tangy, creamy addition.

Sauerkraut: Fermented cabbage that’s high in probiotics and fiber. Enjoy this sheet pan chicken and veggies with a forkful of sauerkraut on the side.

Kimchi: A spicy Korean side dish made from fermented vegetables. We love adding a spoonful of kimchi to this hot honey salmon bowl.

Miso: A fermented soybean paste often used in Japanese cuisine. Miso pasta, anyone?

Kombucha: A tangy, effervescent tea beverage fermented with a symbiotic culture of bacteria and yeast. When we’re in the mood for a mocktail, kombucha always slays.

Pickles: Cucumbers fermented in brine, but look for naturally fermented varieties without vinegar. This autumn grain bowl understands the (pickle) assignment.

Tempeh: A fermented soybean product that’s high in protein and probiotics. These sriracha tempeh spring rolls are the lunch gift that keeps on giving.

How to Combine Intermittent Fasting With Gut-Boosting Foods

To maximize the gut health benefits of intermittent fasting, consider these tips:

1. Break your fast with probiotic-rich foods, like yogurt or kefir.
2. Include fermented vegetables like kimchi or sauerkraut with your meals.
3. Use your eating window to focus on nutrient-dense, fiber-rich foods that feed beneficial gut bacteria.

Sample meal plan for a 16/8 fasting schedule:

Remember to listen to your body and adjust your fasting schedule and food choices as needed.

Potential Drawbacks and Considerations

Before starting your intermittent fasting journey, chat with your healthcare provider—particularly if you have existing gut issues, a history of eating disorders, or any chronic health conditions. And remember, while IF can offer numerous benefits, it’s not suitable for everyone! Potential drawbacks include:

• Initial digestive discomfort as your body adjusts
• Increased hunger and potential overeating during eating windows (to minimize this, start with an 8-hour fasting window at night/while you sleep)
• Possible nutrient deficiencies if not carefully planned

Embracing Intermittent Fasting for Gut Health

By giving your digestive system regular periods of rest (and replenishment via fiber-forward/probiotic-rich foods), you can cultivate a thriving gut microbiome! Remember, the key to success lies in finding an approach that works for your lifestyle. And as always, listen to your body. Whether you opt for a strict intermittent fasting regimen or simply aim to include more fermented foods in your diet, every step toward better gut health is a step toward a healthier you.