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Fasting is all the rage right now, with people using various forms of fasting for different health goals and conditions, ranging from weight loss to enhancement of cognitive function. While we’re currently hearing much about fasting in the media, this practice is far from a fad diet! In fact, research shows that fasting can significantly lower inflammation, improve immune function, and enhance brain function.

Based on these health benefits, fasting can be helpful for many people with Lyme disease. Read on to learn about the connection between fasting and Lyme disease, the health benefits of fasting, and how these benefits can support Lyme disease recovery.

Please note that I am an affiliate for some of the products that I’ve linked to in this post. If you click the link here and make a purchase, I may earn a commission at no extra cost to you.

What is Intermittent Fasting?

There are countless forms of fasting that one can try. However, I’d like to begin by focusing on the most accessible and well-studied type of fasting, intermittent fasting.

Intermittent fasting, abbreviated “IF” for short, is an eating strategy in which you eat meals within a specific period each day and fast the rest of the time. Far from being a diet fad, IF is a practice our ancestors regularly engaged in during times of food scarcity. As a result, fasting is woven into our DNA, and today, scientific research indicates that intermittent fasting offers multiple health benefits.

The term “intermittent fasting” is typically used to refer to a fast that begins with our last bites of dinner and extends overnight and into the following morning. The period overnight, while we are sleeping, is ideal for IF because we are already naturally forgoing food intake; therefore, for most people, this is the perfect time to engage in an intermittent fast.

After about 12 hours of fasting, our blood glucose levels and the storage form of glucose located in our liver, glycogen, become depleted. As a result, our bodies turn on a “metabolic switch” that initiates the burning of fatty acids derived from our fat tissue for energy. Even the leanest individuals have sufficient fat tissue stores that can be used to supply fatty acids for energy during an overnight fast.

However, fat burning isn’t the only metabolic process turned on by intermittent fasting. Our bodies also increase ketone production, activate an anti-inflammatory signaling pathway called the AMPK pathway, and initiate a cellular cleanup process called “autophagy.” (1) Turning on these pathways results in benefits to various body tissues. More on this shortly!

How Long Should Your Intermittent Fast Be?

The ideal intermittent fast length depends on several factors, including the amount of body fat on one’s frame, how well-managed (or not) their blood sugar is, and whether or not one exercises in the morning. Nevertheless, here are a few standard lengths for IF that I recommend in my functional nutrition practice:

• 12-hour intermittent fast: This fast involves fasting for 12 hours between dinner and your first meal the following day and eating within a 12-hour feeding window. This is a good place for most people to start when they are new to intermittent fasting. A 12-hour fast is also ideal for most premenopausal women. Fasting longer than 12 hours can be physiologically stressful for cycling women and deplete estrogen and progesterone levels, compromising hormone balance.
• 14:10 fasting: This involves fasting for 14 hours between dinner and your first meal the following day and eating within a 10-hour feeding window. This fast length is ideal for many perimenopausal, menopausal, and postmenopausal women.
• 16:8 fasting: This involves fasting for 16 hours between dinner and your first meal the following day and eating within an 8-hour feeding window. I recommend this fast to middle-aged men or midlife women dealing with blood sugar issues, such as metabolic syndrome. This type of fast is not appropriate for people with high levels of stress, those who are underweight, and most young, active, and metabolically healthy individuals. I also advise against this type of fast for all premenopausal women.
  • If you want to aim for a 16:8 fast but have never fasted before, start by aiming for 12 hours between dinner and breakfast, then 13 hours, and so on until you hit the 16-hour mark.
• 24-hour fast: Advanced fasters might consider trying a once-weekly 24-hour fast, where just water and electrolytes are consumed. I find that this type of fast works well for most men but doesn’t work well for many women because women’s stress hormones and sex hormones are susceptible to imbalances during prolonged periods of fasting.
  • If you are a candidate for this type of fasting, this could look like fasting from dinner on Sunday night until dinner on Monday night.

What to Expect When Intermittent Fasting

Intermittent fasting may feel a bit uncomfortable at first, especially if you are used to eating every couple of hours throughout the day and into the night. However, if you are consistent with intermittent fasting, your metabolism will adapt, and intermittent fasting will become easier over time.

Of course, if you ever feel dizzy, lightheaded, or sick while intermittent fasting to the degree that concerns you, be sure to consult with your doctor.

Beneficial effects of intermittent fasting that you can expect:

• Enhanced cognition – less brain fog and enhanced focus and processing speed
• Increased energy, particularly in the morning
• Improved gut function, including less bloating and better digestion
• Fewer sugar cravings
• Increased energy throughout the day

Intermittent Fasting and Lyme Disease: How Can This Practice Help Lyme Patients?

Let’s discuss some of the health benefits of intermittent fasting for Lyme disease patients in more detail. There are excellent potential benefits to be had!

Intermittent Fasting Supports the Immune System

A growing body of research indicates that fasting supports the immune system! Fasting primes your immune system, helping it effectively target harmful bacteria and viruses for destruction. It also activates autophagy, your body’s cellular “housekeeping” process that breaks down and recycles dysfunctional cellular components, including dysfunctional immune cells.

Autophagy also can destroy intracellular bacteria. (2) Borrelia burgdorferi and several Lyme co-infections, including Mycoplasma, can reside intracellularly, so autophagy may help combat these intracellular infections! (3, 4)

Fasting also supports a healthy inflammatory response and may thus help reduce chronic inflammation caused by Lyme disease.

Intermittent Fasting Supports Healthy Blood Sugar Control

The inflammation triggered by Lyme disease can compromise metabolic health, causing blood sugar dysregulation. Blood sugar dysregulation refers to blood sugar levels that fluctuate abnormally. Over time, Lyme disease-induced blood sugar dysregulation may cause sustained high blood sugar levels and insulin resistance, which can lead to type 2 diabetes.

An abundance of research indicates that intermittent fasting supports healthy blood sugar control (5, 6), which may help counteract the adverse changes in blood sugar control in people with Lyme disease.

The length of intermittent fasting that will best support your blood sugar control depends on several factors, including the degree of insulin resistance you’re experiencing and the composition of your diet. For example, some people experience improvements in blood sugar control simply by fasting for 12 hours overnight, while others need a longer 16:8 fast to improve their blood sugar control.

Intermittent Fasting Supports Brain Function

Neurological symptoms, including brain fog, headaches, and memory impairment, are common in Lyme disease patients. (7) Neuroinflammation, or inflammation in the brain, is believed to be the common underlying mechanism by which Lyme disease triggers brain-based symptoms.

Intermittent fasting reduces neuroinflammation and increases levels of a brain-repairing signaling molecule called brain-derived neurotrophic factor (BDNF). (8, 9) It also stimulates the body’s production of ketones, which are small molecules that various body tissues, including the brain, can use for energy. Ketones have been found to preserve brain function when the brain is under stress promote the growth of new nerve cells in the brain. Through these mechanisms, intermittent fasting may thus counteract some of the neurological impairments caused by Lyme disease and improve brain function!

Side note: A ketogenic diet significantly upregulates ketone production inside the body and can be helpful for some Lyme disease patients. I discuss this diet in my article on the ketogenic diet for Lyme disease.  

Fasting Supports Our Mitochondria

Mitochondria are organelles, tiny structures inside our cells, that are vital for producing cellular energy, or ATP. ATP is the universal energy source for our bodies. When our mitochondria aren’t functioning well, our cellular energy levels become depleted, resulting in downstream adverse health consequences, including chronic fatigue and neurological dysfunction, including memory issues. (10, 11)

Lyme disease can damage mitochondrial function, leaving us with lower cellular energy levels. (12) In fact, the induction of mitochondrial dysfunction may be a primary mechanism by which chronic Lyme disease causes far-reaching health issues, including fatigue, brain fog, exercise intolerance, and mood issues.

Fasting turns on a pathway inside our cells called PGC-1α, considered the master regulator of mitochondrial biogenesis, creating new mitochondria inside our cells. (13) Fasting may be a valuable tool for helping us recover our mitochondrial function and promote healing from Lyme disease.

Intermittent Fasting Supports Gut Health

Lyme disease can do a number on the gut. It can slow down gastrointestinal motility, causing conditions such as gastroparesis and small intestinal bacterial overgrowth (SIBO).

Intermittent fasting has been found to strengthen the gut barrier, which is the lining of the gut that prevents substances from leaking from your gut into your blood circulation. (14) Compromised gut barrier function causes inflammation, so by fortifying the gut barrier, IF may help reduce systemic inflammation. This is a plus for those of us with Lyme disease who are already dealing with high inflammation levels.

It may also support a healthy gut microbiota! The gut microbiota is the collection of microorganisms in your digestive tract, including bacteria, yeasts, and viruses. Many Lyme disease patients struggle with gastrointestinal issues, such as bloating, diarrhea, constipation, and indigestion caused by a disrupted gut microbiota. Gut microbiota imbalances in Lyme disease can occur due to the infection or be triggered by antibiotic treatments. Research shows that intermittent fasting enhances the growth of beneficial gut bacteria, including Akkermansia muciniphila, which helps protect against leaky gut and chronic inflammation. (15)

Additional Potential Benefits of Fasting

Other potential benefits of intermittent fasting include the following:

• Improved appetite regulation (16)
• Reduced depression and anxiety (17)
• Promotes cellular repair (18)

Other Forms of Fasting That May Help with Lyme Disease

In addition to intermittent fasting, there are several other types of fasting that certain individuals with Lyme disease may benefit from, including early time-restricted eating (early TRE), the fasting-mimicking diet, 24-hour fasting, and prolonged fasting.

Fasting Mimicking Diet (FMD)

Some of my clients with Lyme disease have experienced health benefits from a unique form of fasting called the fasting-mimicking diet, or “FMD” for short.

The Fasting Mimicking Diet (FMD) is an eating program designed to help you achieve the health-promoting effects of fasting while minimizing the adverse effects of prolonged calorie restriction. The FMD involves significantly reducing total calorie intake for three to five days each month—after this three- to five-day period, regular eating habits are resumed for the remainder of the month. This constitutes one cycle of the FMD.

In scientific research, the FMD has been found to support immune system rejuvenation, a potentially significant benefit for those of us with Lyme disease, enhances cognitive function, improves insulin sensitivity and cardiovascular function, and turns on genes in the body that are involved in longevity. (19, 20)

Here are a few key features of the FMD:

• The FMD is low protein, low carbohydrate, and high in healthy fats.
• Minimal animal products are allowed. Bone broth is frequently included.
• Protein should come from plant sources during the FMD, such as almonds and pumpkin seeds.
• Fats should come from healthy plant sources, such as avocado, olive oil, and coconut oil.
• Micronutrients are supplemented in the form of sea salt.

Calorie and macronutrient (protein, carbohydrate, and fat) intakes must adhere to specific guidelines on the FMD. The FMD isn’t just about cutting calories temporarily; it’s about cutting particular types of calories (primarily carbohydrates) to shift the body into burning fat and ketones for fuel, which in turn turns on other biochemical pathways inside the body that reduce inflammation and support the immune system.

How to Calculate Calorie and Macronutrient Needs on the FMD:

Day 1:

• Total caloric intake should be 4.5–7 kcal/lb. of body weight.
• Macronutrient ratios: 10% protein, 56% fat, 34% carbs.
• Sample calculation for caloric intake: Patient weighs 150 lbs.
  • 4.5 kcal x 150 lbs = 675 kcal
  • 7 kcal x 150 lbs = 1050 kcal
• The possible calorie intake range for Day 1 for a 150-pound male would be between 675 and 1050 kcal.

Day 2:

• Total caloric intake should be 3–5 kcal/lb. of body weight.
• Macronutrient ratios: 9% protein, 44% fat, 47% carbs.
• Sample calculation for caloric intake: Patient weighs 150 lbs.
• 3 kcal x 150 lbs = 450 kcal
• 5 kcal x 150 lbs = 750 kcal
• The possible calorie intake range for Days 2–5 for a 150-pound male would be between 450 and 750 kcal.

After Day 5, regular eating habits are resumed until the next FMD cycle is completed (should you decide to do another cycle).

The FMD can be done using the Prolon meal kits, or you can do a DIY version, adhering to the calorie and macronutrient guidelines I’ve provided above.

Early Time-Restricted Eating

Research indicates that our bodies are metabolically primed to obtain most of our calories earlier in the day rather than later, as we tend to do in our culture. Early time-restricted eating (early TRE) is an eating strategy in which you shift your meals earlier in the day and wrap up eating for the day by around 4 pm or earlier. You then fast from 4 pm until your first meal the following morning.

Early TRE is an excellent strategy for improving insulin sensitivity and blood sugar control and supporting fat loss in individuals who want to become leaner. Scientific research corroborates these health benefits! According to the research, the health benefits of early TRE include the following:

• Improves insulin sensitivity and blood pressure and decreases oxidative stress (21, 22)
• Increases expression of the anti-aging gene SIRT1 (23)
• Reduces appetite (24)
• Increases fat burning (25)

24-Hour fasting

This is a more advanced strategy, as most people today have rarely gone without food for 24 hours due to 24/7 food availability. However, 24-hour fasting may offer unique health benefits, including upregulated autophagy in the brain, which helps clear out damaged brain components, and increased brain-derived neurotrophic factor. This protein stimulates the growth of new brain cells and may, therefore, support brain health. (26, 27)

Prolonged Fasting

Prolonged fasting refers to fasting that is carried out for 24 or more hours. No food is consumed, but noncaloric beverages, including water and coffee, are typically consumed during a prolonged fast.

I only recommend doing prolonged fasting under the guidance of a qualified healthcare provider. If prolonged fasting is done incorrectly, it can have serious health consequences, such as dehydration and electrolyte imbalances.

Who Shouldn’t Try Intermittent Fasting?

While intermittent fasting can benefit many Lyme patients, there are several crucial caveats: If you are pregnant, breastfeeding, underweight, have an active eating disorder, or are recently recovered from an eating disorder, I advise against intermittent fasting because it is a catabolic process that uses up energy reserves, can reduce your appetite, and may promote unnecessary weight loss.

Fasting and Lyme Disease FAQ and Tips for Making the Most of Your Fast

Can I overdo fasting?

In short, yes, it is possible to overdo fasting. However, if you are fasting so much that it’s interfering with your ability to meet your body’s nutritional needs, this is a problem. This is why I recommend working with a functional healthcare professional with experience putting together fasting protocols to determine the right type and frequency of fasting for your body’s needs.

Can I exercise while intermittent fasting?

Yes, you can exercise while intermittent fasting; however, the type of exercise you perform while fasting matters.

Intermittent fasting and physical activity can work synergistically at certain intensity levels and times of the day. For example, if you engage in low-intensity aerobic activity first thing in the morning, such as walking, cycling, or jogging, you can fast during that activity. In fact, fasting during low-intensity exercise can “turn on” the metabolic machinery that allows your body to utilize body fat for fuel.

However, if you engage in moderate- or high-intensity physical activity first thing in the morning, you should break your fast with a small meal before exercising. Intermediate- and high-intensity exercise relies more on the glycolytic pathway for energy production, so having some carbohydrate fuel on board will help you perform better.

What Breaks a Fast?

People often ask me if eating certain foods or drinking certain beverages will kick them out of their intermittent fast. Technically, consuming any caloric food or beverage (other than water, tea, or black coffee) will break your fast.

However, you can consume some pure fat, such as butter (if you’re a Bulletproof coffee person), while fasting and maintain most of the biochemical processes activated by fasting because pure fat doesn’t elicit an insulin response. Rising insulin levels shut down the biochemical processes activated by fasting, including lipid oxidation (aka “fat burning”) and ketone production.

Factors that will definitely break a fast include:

• Protein powder, such as collagen powder
• Branched-chain amino acids (BCAA): BCAA are amino acids our bodies use to make proteins. Because they are building blocks for protein, consuming them will break your fast.
• Any caloric food other than pure fat that contains protein and/or carbohydrates. Examples of pure fats include coconut oil, MCT oil, and butter; these will not break your fast.

How to Break Your Fast

Choose nutrient-dense, whole foods when breaking your fast, not just a big bowl (or plate) of carbohydrates!

After fasting, your body is more sensitive to carbohydrates than usual. If you sit down to a bit bowl of cereal or oatmeal or a plate of French toast right after your overnight intermittent fast, you’ll likely experience a significant blood sugar spike in response to those carbohydrates. Shortly after this spike, your blood sugar level will plummet, resulting in symptoms such as brain fog and sugar cravings.

Instead, break your fast with a meal balanced in protein and fats, with a modest amount of carbohydrates from a nutrient-dense food source, such as whole fruit or baked sweet potato.

A Potential Drawback of Intermittent Fasting: Under-Eating Protein

One potential downside of intermittent fasting is that it may be challenging to meet your protein intake needs. More prolonged intermittent fasting (16+ hours) significantly shortens the time you have to eat daily. If you only eat twice a day while intermittent fasting, you will likely need to eat more protein cumulatively with those two meals to meet your daily protein needs.

Tracking your food intake for several days on Cronometer, the food tracking app that I recommend, while on your usual intermittent fasting schedule, will allow you to see how much protein you’re consuming. If you’re coming in under 75 grams of protein a day, you’ll either need to increase your protein intake during your eating window or reduce the length of your fasting window to make more time for eating.

Final Thoughts on Fasting and Lyme Disease

Fasting offers a plethora of health benefits for individuals with Lyme disease. When fasting is implemented alongside a nutrient-dense, whole-foods diet, it can improve immune, brain, and gut function and may even alleviate certain Lyme disease symptoms.

If you’re interested in using fasting to aid your Lyme disease recovery but are unsure where to start, I’d love to help you! I am currently accepting new clients in my functional nutrition practice. Schedule a discovery call with me to learn more about how I can help you!