Fasting: A Path to Healing & Its Benefits

Author: Deborah Ng SJ

What is Intermittent Fasting?

Intermittent fasting isn’t a specific diet but rather a way of eating. It involves alternating between periods of fasting and eating; it is also known as time-restricted eating.

During your fasting window, you go without food for a set time, usually between 12 and 24 hours, but without enduring nutritional deficiency, it is a pattern of eating rather than a particular diet type.

Fasting and Autophagy

Fasting leads to autophagy, the body’s self-preservation mechanism for cleaning out damaged cells and renewing itself. Studies from animals show that fasting for 24-48 hours can activate this process (10).

Fasting benefits people with obesity because obesity is often linked to cancer, accompanied by several factors such as chronic inflammation, changes in hormones, and insulin problems.

What is Mitophagy?

Mitophagy is the process by which cells remove damaged or dysfunctional mitochondria (the energy-producing parts of the cell) to keep the cells healthy.

Mitophagy helps prevent cancer by removing mutated mitochondrial DNA. This process is vital for reducing the risk of tumor formation and maintaining cellular health.

In this article, we will explore:

1. Healing benefits of autophagy from fasting

A thorough literature review of 71 research studies from all sources of the database, including Medline, Web of Science, Scopus, and Google Scholar, summarizes that (1):

Caloric Restriction (CR) and Mitophagy: Caloric restriction (eating fewer calories from fasting) is one of the most potent non-genetic ways to trigger mitophagy.

Note: CR's eating pattern, despite eating fewer calories or reducing caloric intake, doesn't cause malnutrition. In other words, CR chooses higher-quality and nutritious food with fewer calories.

Induces mitophagy and mitophagy-related markers: CR and fasting hold a promising role in preventing age-related diseases without any side effects. Most studies found that Binp3 and Parkin (both mitophagy-related markers) have increased, suggesting a potential avenue for disease prevention.

Beneficial effects from fasting:

Upregulating autophagy
Reducing inflammation and stress oxidative damage
Decreasing cell proliferation rates
Increasing mitochondrial health

The health benefits of fasting result in the overall reduction of:

Insulin level
Leptin
Body fat
Blood pressure
Increase longevity

Positive health outcomes from age-related disorders such as :

Huntington's disease
Alzheimer's disease
Parkinson disease
Metabolic disorders such as:
Cardiovascular diseases
Diabetes mellitus
ROS, reactive oxygen species (Oxidative stress and cellular damage)
And even cancer

2. Does fasting help your brain?

Infographic credit: Dr. Jockers.com (3)

A study of older adults who have mild cognitive impairment (MCI)—over 60 years old—showed higher rates of "successful aging" (better cognitive and functional ability) in those who practiced intermittent fasting compared to non-fasters (4).

Mini-mental state examinations (MMSE) were administered to examine this. A score above 22 was required to show that they are maintaining good functional ability and enjoying the quality of life.

24.3% of elders in the regular fasting group achieved this, while only 3.1% of the non-fasting group achieved this score. Hence, IF significantly contributes to healthier aging accompanied by improved cognitive functioning.

Can you eat whatever you like during

non-fasting hours?

Despite that, fasting has proved to be beneficial compared to people who do not fast at all. It is interesting to see whether the Ad Libitum Diet has different effects than the caloric restriction diet.

Note: Ad libitum eating is a term used to describe eating as much as you want, without any imposed restrictions on the quantity or quality of food intake during fasting hour.

A study with 220 healthy, non-obese volunteers (22 to 28 BMI) over 2 years showed that (5):

The volunteers were divided into 2 groups:

Group A: Reducing 25% of their calorie intake while fasting
Group B: Ate as much as they want without limitation
Working memory tests were carried out, such as specific cognitive tests and focusing on error tests and strategies.
Factors such as sleep quality, mood, stress, and physical activity were also measured.

Group A showed significant improvement in working memory compared to Group B. Improvements were associated with better sleep quality, increased physical activity, and changes in energy use.

3. Does fasting help fight cancer?

Since there are so many benefits to Intermittent fasting? Does it work for cancer patients who are undergoing cancer treatments such as chemotherapy?

The answer is Yes from 73 women and 28 men; the majority are women (56) with breast cancer (2), followed by 10 with colorectal cancer and other types of cancer such as lung, prostate, pancreatic, melanoma, reproductive cell, ovarian, thyroid, stomach, kidney, uterine and bone marrow cancer.

Overall, only 12.9% of people reported side effects, such as low blood sugar and fatigue, which were the most common; however, they were primarily mild to moderate, suggesting that fasting was safe and well-tolerated.

Procedure:

Before the fasting, Researchers collected the levels of immune cells in the tumor and specific immune genes in the tissue samples taken using biopsies.

After the fasting, Levels of the same immune cells and genes in the tissue samples were taken during surgery after the first five days of fasting.

Results:

The results showed more immune cells were in the tumors after the diet. The immune genes also changed, suggesting that the immune system started recognizing and attacking the cancer.

Moreover, patients' blood glucose levels had reduced by 18.6%, insulin levels by 50.7%, and insulin-like growth factor 1 (IGF-1) levels by 30.3%. IGF-1 is a hormone that helps stimulate cell growth and development, including cancer cells, especially in breast cancer.

4. Fasting and insulin levels, why is it so important?

Now that we know that fasting impacts insulin levels, why is it so important? Is insulin resistance associated with disease?

Yes, often, a person with high insulin resistance will have a higher risk of getting these associated diseases:

Metabolic syndrome
Obesity
Prediabetes or type 2 diabetes
Polycystic ovarian syndrome (PCOS)
Non-alcoholic fatty liver disease (NAFLD)
Microvascular disease (retinopathy, neuropathy, or nephropathy)
Macrovascular disease (stroke, PAD, and CAD)

Note:

Retinopathy: Damage to the small blood vessels in the retina, the light-sensitive tissue at the back of the eye, often caused by high blood sugar levels over time, commonly seen in diabetes.

Neuropathy: Damage to the nerves, often affecting the peripheral nerves in the hands and feet, leading to poor nerve function. It can cause numbness and tingling.

Nephropathy: Damage to the small blood vessels in the kidneys, affecting their ability to filter waste from the blood, may include protein in the urine, swelling in the feet and ankles, and kidney failure if untreated.

What happens when insulin levels are high?

How does insulin sensitivity help in metabolic disorders that are associated with cancer prevention?

The insulin signaling pathway is crucial for managing the body's energy use and storage. Here's how it works in relation to cancer (6):

Insulin and Receptors: Insulin binds to specific receptors (INSR-1, INSR-2, and IGF1R) on cell membranes. This binding starts a chain of events that helps maintain energy balance.

Glucose Uptake: When insulin activates these receptors, it increases glucose uptake into cells through a pathway called PI3K/Akt.

Energy Processes: Insulin also triggers processes like glycolysis (breaking down glucose for energy), glycogenesis (storing glucose as glycogen), and lipogenesis (storing fat). It does this by activating certain enzymes and inhibiting others.

Hence, this is why people with insulin resistance are often overweight, as their body stores fat more easily.

Reducing Gluconeogenesis: Insulin minimizes glucose production in the liver by affecting a protein called FOXO1.

On the contrary, when insulin resistance occurs, FOXO1 promotes gluconeogenesis by activating genes that increase glucose production in the liver.

Aging and Hyperglycemia: High blood sugar levels (hyperglycemia) can increase aging-related factors and oxidative stress in cells, which are directly caused by insulin resistance.

What are the effects of insulin in the body?

The whole process illustrated above shows how insulin resistance directly affects energy maintenance, nutrient storage, and cell maintenance and regulation processes, with complex interactions between different pathways.

5. Fasting and Coronary artery disease (CAD)

A fasting behavior survey was conducted with a total of 648 patients undergoing coronary angiography test using meta-analysis, and here is the result (9):

Fasting behavior patients:

10.3% had diabetes mellitus

Had a 53.2% lower chance of getting diabetes mellitus

63.2% of fasting behavior patients were diagnosed with coronary artery disease (CAD)

Average Glucose levels were 108 mg/dL (5.99mmol/L).

The average BMI was 27.9 kg/m²

v Non-fasting behavior patients:

22% had diabetes mellitus

Had a 113.5% higher chance of getting diabetes mellitus

75% of Non-Fasting behavior patients were diagnosed with CAD

Average Glucose levels were 115 mg/dL (6.38mmol/L)

The average BMI was 29.0 kg/m²

6. How does the body utilize energy during fasting?

ATP, or adenosine triphosphate, is the primary energy carrier in all living organisms. During fasting, the body's metabolism undergoes significant changes to adapt to the reduced availability of external nutrients.

Here's how ATP production and utilization are happening during fasting:

Glycogenolysis: In the early stages of fasting, the body breaks down glycogen stored in the liver to maintain blood glucose levels. This process provides glucose for ATP production through glycolysis; hence, the body still relies on glucose for energy.

Gluconeogenesis: As fasting continues and glycogen stores are depleted, the body starts producing glucose from non-carbohydrate sources like amino acids (from protein breakdown) and glycerol (from fat breakdown); they are used to generate ATP.

Keto diet, also known as high fat but with little to no carbs, can assist in Gluconeogenesis. However, fasting has a stronger and faster effect in achieving this (8):

Lipolysis and Ketogenesis: Prolonged fasting (over 24 hours) leads to an increased breakdown of fat stores (lipolysis) to release fatty acids and glycerol.

Fatty acids are then converted into ketone bodies in the liver (ketogenesis), which can be used as an alternative energy source by many tissues, including the brain.

However, this process still preserves muscle protein and maintains ATP levels. Hence, losing muscle mass is impossible if you fast for less than 24 hours.

Protein Catabolism (7): In extreme or prolonged fasting*, the body may resort to breaking down muscle proteins for energy, although this is generally minimized to preserve muscle mass.

*Extreme or prolonged fasting for more than 24 hours to 48 hours.

Overall, ATP production during fasting relies more on fat metabolism and the use of ketone bodies, while glucose metabolism becomes secondary. This metabolic shift helps the body efficiently utilize energy reserves and maintain ATP levels during periods of low nutrient intake.

What are the protein intake recommendations for prolonged fasting?

Consuming adequate protein is advisable if you wish to go through prolonged fasting without losing muscle mass.

Pre-Fasting Period (before doing the 24 hours fasting) & post-fasting:

Focus on protein-rich meals to support muscle repair and recovery:
1.6 to 2.2 grams per kilogram of body weight
Example: For a person weighted 70kg x 1.6 to 2.2 g = 112 to 154 grams of protein before and after fasting.
Aim for the higher-end spectrum for a person with less muscle mass.