The Benefits of Intermittent Fasting

Glass of water with lemon and mint

While fasting has been around for eons, it has recently gained a resurgence in popularity and for good reason. In today’s world, you can’t turn the corner without running into food – it’s everywhere. And most people rarely reach a state of fasting for any length of time, which goes against how our systems WANT to function. Eating every 2-4 hours isn’t biologically how we as human adults operate best.

Intermittent fasting has gained traction in the last few years in the realm of weight loss and fitness, and even optimizing brain function, but there are several other benefits to fasting and a variety of ways to go about it. It’s important to remember that while fasting, maintaining optimal nutrition is imperative. It’s also important to consult your provider prior to partaking in a fast, especially if you have hypoglycemia or diabetes or are taking medications.

The History of Fasting

Since the beginning of time, all life forms have been able to make adaptations in relation to the light/dark cycle. This predictable rhythm includes changes in food availability. In human history, this meant acquiring food when accessible and storing additional food in anticipation of a period of rest and recovery, which allowed for optimal fitness and bodily repair [1].

Fasting has been a part of many cultures and groups for much of the world’s history. In ancient Greece and Egypt, fasting was a part of prevention and treatment of disease, similar to the resurgence we see today.

Philosophers and great thinkers including Plato, Hippocrates and even Benjamin Franklin all recognized the power of fasting. One of the three fathers of Western medicine, Paracelsus, is quoted as saying, “Fasting is the greatest remedy–the physician within.”

Fasting has also had a long-standing history with spiritual and emotional benefits in several world religions. These aspects of fasting can be thought of as part of an act of intention, or something done with a mindful approach. This process is often described as an avenue to becoming more deeply in touch with yourself by experiencing a “need or challenge,” leading to greater self-awareness and sensation, all while training your mind and body.

“I often observe in the fasting participants that by four days of fasting, concentration seems to improve, creative thinking expands, depression lifts, insomnia stops, anxieties fade, the mind becomes more tranquil and a natural joy begins to appear. It is my hypothesis that when the physical toxins are cleared from the brain cells, mind-brain function automatically and significantly improves and spiritual capacities expands.”
Gabriel Cousins, M.D. (Psychiatry)

The Top 5 Ways To Fast

  1. Alternate-Day Fasting: This entails eating only every other day. On fasting days, some eat no food at all and others eat a very small amount, typically around 500 calories. On non-fasting calorie days, eat normally (but healthfully!)
  2. The Warrior Diet: This diet involves eating only fruits and vegetables during the day and then eating one large meal at night.
  3. Time-Restricted Feeding: For this method, you fast for a number of hours every day. The most common include: overnight (fasting for 12 hours), brunch fast (fasting for 14 hours), or a strong fast (fasting for 16-18 hours).
  4. Eat-Stop-Eat: Pick one or two days out of the week and fast for 24 hours, eating nothing from dinner one day until dinner the next day. On the other days, you should have normal calorie intake.
  5. 5:2 Diet: For five days of the week, you eat normally. For the remaining two fasting days, calories are restricted to between 500–600 calories. . There are debates around what you can consume during a fast. Commonly, fasting regimens include water and electrolytes. However, some people may benefit from using broth, juices, or green tea.

The Key Benefits of Fasting

When you avoid food for an extended length of time, certain processes upregulate in the body that help you get rid of damaged cells, help you produce new stem cells (like turning back the clock!) and even help repair a leaky gut – a common ailment in our patients of all ages. Some other benefits of fasting include:

Promotes weight loss

In a state of calorie restriction, the body doesn’t receive a regular surge of glucose, or sugar, which is the most readily absorbed form of energy. When glucose is broken down into glycogen, the body will use this for energy until its stores are depleted, at which point the body turns to fat cells to keep going. Similarly, the ketogenic diet is based on the deprivation of glucose, or carbohydrates, forcing the body to use stored fat. Fasting also promotes greater release of human growth hormone which has been shown to help increase muscle strength and combat obesity [5].

Supports blood sugar balance

Studies have shown that fasting can help improve insulin sensitivity and maintain glucose homeostasis, which also promotes weight loss [3]. When consuming higher amounts of carbohydrates and sugars, the body can become insulin resistant, which in many instances precipitates various chronic diseases, namely Type II Diabetes. The study published in the World Journal of Diabetes found that fasting can help reduce visceral fat mass, fasting insulin, and insulin resistance, improving body weight and glucose levels [6].

Reduces inflammation

Nutritional habits, in general, can significantly prevent or contribute to chronic inflammation, which can lead to disease. Intermittent fasting has been shown to improve markers of oxidative stress and inflammation, even after just two weeks, as well as elicit changes in energy metabolism, furthering the success of weight loss [7].

Supports gut healing and microbial diversity

The gut is composed of over 100 trillion microbes, which together contain more than 100 times the number of genes in the human genome! Some of the functions of the microbiome include nutrient absorption and the breakdown of food, xenobiotic (foreign substance) metabolism, and promotion of gut barrier function which is integral to gut and brain health. Scientists now know that nearly 80% of our immune function starts in the gut, and this intricate network of bacteria are significant determinants of our overall health. Additionally, there’s increasing evidence connecting the health of the microbiome to the incidence of autoimmune disease, including Multiple Sclerosis, among others [4].

Supports detoxification

Studies are emerging that suggest the efficacy of intermittent fasting as it relates to detoxification through the liver. Detoxification is tightly connected to metabolic function, and some of the best studies regarding optimal detoxification include healthy foods and nutrients, and now increased evidence supports intermittent fasting can contribute to optimal detoxification as well [8].

Good for the brain and cardiovascular system

Studies suggest that the benefits for the brain and cardiovascular system are similar to those of physical exercise. Fasting improves blood pressure, insulin sensitivity, resting heart rate and levels of oxidative stress. Risk factors for cardiovascular disease, stroke, diabetes, coronary artery disease, and more, have improved in rats and monkeys while on a fasting diet [2].

How does fasting work?

Digestion takes a lot of energy for the body, so periodically removing the need for digestion can enhance healing throughout the body. Fasting allows the body to use up stored sugar (glycogen), which is the easier-to-burn fuel. After this is accomplished, the body will tap into stored fat for energy. After the first 24-48 hours of fasting, the body shifts into ketosis. This is where the magic happens! Hunger diminishes, body fat is used as fuel, energy soars, focus improves and this is also when autophagy and stem cell production really ramp up.

“Therapeutic [water] fasting accelerates the healing process and allows the body to recover from serious disease in a dramatically short period of time.”
Joel Fuhrman, M.D.

Who shouldn’t fast

As enticing as the benefits from fasting are, it isn’t for everyone. If you fit into any of these categories, please do not fast.

  • Eating disorder – history of or presently have
  • Underweight
  • Pregnant women & those with newborns or those who are nursing
  • Young children
  • Type I diabetes
  • Extreme athletes
  • On certain medications
  • Malnourished
  • Possibly those with adrenal/HPA axis dysfunction

What to know before you begin to fast

Jumping directly into fasting without priming the body to use stored fat as fuel will leave you feeling weak, lethargic, flu-like and with headaches. This is known as the “carb flu.” Slowly transitioning to a higher fat, lower carb, low-moderate protein diet before you attempt to fast will help you avoid this. Additionally, do not embark on a fast longer than 24 hours without talking to your provider. There are a few things to know coming out of a fast to help you transition back to food. You must consume a lot of water and possibly electrolytes during a fast, especially longer fasts. Additionally, if you have been eating a very poor diet that is lacking nutrients, it would be wise to take at least a month to replete prior to doing longer fasts.

How to Start a Fast

As mentioned above, it’s important to be intentional about your fast, whether it’s for weight loss, health goals, or spiritual and emotional wellbeing. Having your goals in mind will not only help you stick with it but can actually help improve the outcome!

Decide which style of fasting may work best for you and start gradually. Consider starting with a shorter duration, such as an additional hour or two before your first meal of the day, or slowly shorten your “eating window” during the day. This allows for your mind and body to adjust.

Remember to listen to your body. Our bodies learn our daily patterns and adapt when trying something new, but the rules aren’t to be rigid. For the best chance of success, if you feel it’s necessary to break your fast sooner, then that’s OK! If you aren’t quite hungry or circumstances don’t allow you to eat sooner, then it’s OK to wait a little longer for food. Just ensure you’re adequately hydrated and consume nutrient and mineral dense food while you are eating.

You can exercise during a fast, but experiment and find a time that works best for you.

While fasting, it’s important to ensure that any beverages are also low to zero calories and it’s recommended to avoid alcohol altogether. Water, herbal tea, coffee (without milk and sugar) and sometimes even bone broth can be consumed during fasting.

One final tip: when you do eat, focus on calories coming from highly nutrient-dense foods. You worked hard to help your body optimize how it functions – don’t undo your work with poor quality, nutrient-poor foods. If you aren’t sure if you are a good candidate for fasting, or would like a diet check-in, schedule a session with Rachel Wood, Newbridge integrative nutritionist, to get started.


  1. Fasting, circadian rhythms, and time restricted feeding in healthy lifespan
  2. Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems
  3. Effects of Ramadan fasting on glucose homeostasis and adiponectin levels in healthy adult males
  4. Emerging Concepts on the Gut Microbiome and Multiple Sclerosis
  5. Low-dose growth hormone treatment with diet restriction accelerates body fat loss, exerts anabolic effect and improves growth hormone secretory dysfunction in obese adults
  6. Effects of intermittent fasting on health markers in those with type 2 diabetes: A pilot study
  7. Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma
  8. Enhanced Phase II Detoxification Contributes to Beneficial Effects of Dietary Restriction as Revealed by Multi-platform Metabolomics Studies