Intermittent Fasting 
Intermittent fasting (IF) is defined as a variety of eating patterns where no or few calories are consumed for periods of time that can span 12 hours to several days, on a recurring basis, and can result in a number of different physiological responses.
 
Below are a few common IF approaches:
 

• Time-restricted feeding—Having all of your meals during an 8-12 hour window each day, drinking only water the rest of the day.

• Alternate day fasting—Eating typical amount of food one day but only a minimal amount of calories the next; alternating between “feast” days and “fast” days.

• 5:2 eating pattern—Consuming meals regularly for five days per week, then restricting to no more than 600 calories per day for the other two. This happens by eating very little and drinking only water on those two fasting days.

• Periodic fasting—Caloric intake is restricted for several consecutive days and unrestricted on all other days. For example, fasting for five straight days per month.

 
Why even consider intermittent fasting?
Food is nourishing and we want to be well nourished. Why would anyone consider having a fasting period in their day or week?!
 

1. Fasting improves immune regulation

2. Fasting stimulates cellular autophagy

3. Fasting improves insulin sensitivity

Caloric Restriction
A calorie restricted dietary regimen limits the total calorie intake to ≈15–40% relative to ad libitum without malnutrition. Early studies have found that caloric restriction has profound effects on a series of diseases, such as cancer, Alzheimer's disease, Parkinson's disease, multiple sclerosis, obesity, and diabetes as well as many other metabolic disorders. That said, simply restricting calories is not an easy task and also must be done strategically to maintain lean muscle mass.

 
Fasting Mimicking Diet (FMD)
A fasting mimicking diet (FMD) is a temporary low-calorie diet where the body perceives it’s in a fasting state yet is being nourished. The most well recognized FMD is ProLon. ProLon consists of a 5-day FMD program and the published research is based on repeating that 5-day program every month for three consecutive months. While weight dependent, on average, one consumes 1150 calories on day 1 and then 600-800 calories on days 2-5.
 

Prolonged Fasting
Fasting for longer than 16 hours, particularly fasting for 24-48 hours, also seems to cause cells to initiate a waste-removal process called autophagy. During autophagy, the body cleans house and starts regenerating itself—eliminating dysfunctional, damaged cells to make room for new, healthy ones. Autophagy may offer protection against diseases like cancer or dementia. Additionally, fasting for extended periods of time, starting at about 16 hours, activates genetic pathways that stimulate the process of autophagy. mTOR and PPAR gamma are two of the primary genes activated. These genes influence factors such as insulin sensitivity and lipid metabolism.
 
Benefits of Prolonged Fasting for 4 or more days:

• cell reproduction slows down significantly

• high levels of cellular autophagy occur

• stem cell production increases

Is fasting right for you?

While IF is generally considered safe, not everyone finds fasting beneficial. And you may find that the effects of fasting for you as an individual vary at different periods of time. If you do decide to consider some type of fasting, do so gradually. For example, slowly increase your overnight fast by one hour.
 
Fasting is NOT recommended for children, adolescents, pregnant, and nursing women. IF is also not appropriate for those with disordered eating challenges, chronic liver or renal vascular disease. If you are diabetic, be sure to consult your healthcare practitioner to be carefully monitored if considering any type of fasting protocol. Cycling women should liberalize their fasting regimen during their menstrual cycle.

Be aware that fasting too aggressively for your body increases cortisol levels because the body interprets starvation as stress. High levels of cortisol as well as extended periods of high cortisol lead to high insulin and blood sugar levels. Elevated cortisol levels also impede our digestion, so when you eat, you don’t digest as well, especially if you eat a larger meal, leading to bloating, gas, and food sensitivities.
 

Tips to Help with Fasting

• Hydration is key - be sure to consume plenty of fluids

• Include electrolytes daily – electrolyte minerals assist in energy production

• Practice deep breathing exercises

• Add magnesium for improved adrenal health

• Opt for a light meal when breaking your fast

• Aim to sleep at least 7-8 hours nightly

• Allow for stress recovery activities to help your cortisol levels reset

• Aim to stop eating for the day by 7pm or 8pm, if possible

• If you’re undergoing chemotherapy, consider fasting or avoiding carbohydrates the day prior, day of, and day following your treatment. Be sure to discuss with your healthcare team.

Summary
The primary reason for any dietary change is to have a sustainable and healthy lifestyle that helps you meet your health goals. Whether you’re looking to lose weight, prevent disease, improve autophagy, IF is one eating style that may (or may not) work for you. Both IF and CR protocols show promise in improving weight loss, blood lipids, glucose metabolism, and insulin sensitivity and reducing oxidative stress and inflammation. Most importantly, do your best to consume all of your essential nutrients, appropriate amounts of food, and enjoy your lifestyle.

I'll focus on the various health aspects of fasting and dive into some research in the next newsletter.


In health,
Natalie