Intermittent Fasting (IF) refers to a dietary regimen that establishes periods of the 24 hour day into eating and non-eating periods.  Options include: 12 hours fasting with a 12 hour eating window, up to 16 hours of fasting with an 8 hour eating window. Most commonly, this is achieved by abstaining from food beginning in the evening, say around 8 pm, and having the first meal the next morning.  If doing a 12 hour cycle, the morning meal would begin at 8 am, if doing a 16/8 hour cycle, the first meal would begin at noon.  Some people take “intermittent” to mean abstinence of food anywhere from 12 to 18 hours, and may vary these throughout the week.

Intermittent Fasting Benefits: Is Intermittent Fasting Just Another Fad?

The short answer is no. Although not a lot of human studies have been done about Intermittent Fasting, this is in no way a new phenomenon. In 1900, an American physician by the name of Edward Hooker Dewey wrote a book called The No-Breakfast Plan and Fasting Cure.

The premise of his book, is that we should eat when we are hungry.  The lack of hunger indicates Nature’s need to heal and digest existing food and to successfully function and fight against the disease, there must be adequate time to fully digest and absorb a meal, and another meal shouldn’t be introduced too early. He suffered from headaches and digestive upset most of his life until he awoke one day and went without his breakfast, which he ate more out of habit than hunger. It was the first day he felt truly well, and he adopted the No-Breakfast Plan for himself. But Intermittent Fasting is more than just “skipping breakfast”.

Benefits reported by Intermittent fasting include weight control, improved energy, reduced brain fog, reduced abdominal pain, gas and bloating, better insulin and blood sugar control, improved sleep, down regulating inflammation, improved blood lipids, reduced oxidative stress. 

How is Intermittent Fasting Different Than Other Fasts

While there may be some calorie reduction during Intermittent Fasting, it does not focus on this aspect. Instead, the focus is on giving the digestive tract a chance to fully digest, absorb, eliminate and heal properly. Intermittent Fasting is a lifestyle, whereas other fasts are for specific, often short-term periods of time.

16:8 Diet

This is the most common version of intermittent fasting. It involves restricting your eating window to eight hours per day, while fasting for the remaining 16. People will consume all their calories for the day between, for example, 10am and 6pm or 12pm and 8pm.

Technically, people are allowed to eat whatever they want within that window, but we suggest sticking to nutrient-dense and energy sustaining whole-foods diet to achieve maximal results. Experts also suggest, as reported by Prevention, starting your eating window earlier in the day because blood sugar control and metabolism tend to be higher in the morning. This will help burn calories more efficiently.

How Intermittent Fasting Helped This Doctor Lose 125 Pounds in 18 Months

In life, sometimes it takes drastic events to take place before we take action. For Fairhaven, Massachusetts physician, Dr. Kevin Gendreau, it was his 32-year-old sister’s battle with ovarian cancer. After watching the aggressive disease take her life, he had a wake-up call.

At the time, 5’9” Gendreau weighed in at 300 pounds. This extreme weight gain began in his first year of college, where he tacked on 50 pounds due to stress-eating. But it got even worse when Gendreau found comfort in food after a fight with melanoma took his father’s life that continued through medical school.

“My poor sister, Rachel, she had no choice with her health,” said Gendreau.
“I was choosing to be unhealthy.”

In hindsight, Gendreau realized that many of his health problems – depression, sleep apnea, diabetes, high blood pressure and cholesterol – were linked to an unhealthy lifestyle. It was that realization which kickstarted his lifestyle change. That was back in August 2016…

Gendreau started by simply cutting out processed carbs and limited his calorie intake to 1,700. Those two tweaks resulted in an almost immediate 40-pound weight loss. However, like many will relate to, he hit a plateau in his weight loss journey – a barrier that can make or break one’s progress.

“Ninety percent of my weight loss… is from diet.”

However, Gendreau acknowledged the reality and adjusted his diet accordingly. In addition to keeping out processed carbohydrates, he also consumed more:

  • Chicken
  • Turkey
  • Legumes
  • Vegetables
  • Black coffee
  • Tea
  • Non-fat Greek yogurt
  • Fruit
  • Raw nuts

“When you have a history of binge eating and emotional eating, you have lost all faith in your ability to control your emotions and hunger,” he said. “I had no idea I was as mentally strong as I actually am.”

However, despite making progress, Gendreau could not seem to get his weight down past 225 pounds. It wasn’t until his sister Rachel’s death in June 2017 that he started intermittent fasting, specifically the 16:8 diet. Although it’s hard to eat within an eight-hour window every day, knowing he would need to be even more involved with his sister’s two young children kept him motivated and accountable. Turns out, this type of intermittent fasting helped Gendreau lose another 60 pounds.

“I am shocked it works. There is always a new diet but this is very medically sound, which is why I loved it.”

But this 125-pound weight loss didn’t happen overnight; it took a year and a half and he recommends following three tips:

  1. Keep one pair of old pants and pictures. Gendreau believes keeping one reminder of old clothes and side-by-side pictures will remind you of how far you’ve come and how much progress you’ve made.
  2. Find your reason.For Gendreau, his motivation was rooted in losing both his father and sister. This may look different for you, but it’s important to have a motivator that helps keep you accountable and health.
  3. Spoil your appetite. Before going out to eat, he eats a handful of nuts or carrots and an apple. That way, he’s only hungry enough to consume a drink and salad. That way, you’re not only saving money but keeping your body fueled with high-quality whole foods.

Other Types of Fasting

While Intermittent fasting is a better option for long term health maintenance, there may be times when a shorter duration fast, that usually involves some degree of calorie restriction or eating very specified types of food, is prescribed by your health professional.  It is important that you have clearance by your doctor before starting a more extreme type of fast.

Juice Fast

This type of liquid fast is usually undertaken for cleansing and weight-loss purposes. Unless there are specific health restrictions which disallow for solid foods, there is no fixed rule for when or how often juicing fasts can occur. Individuals may choose a strict regimen of only fruit or vegetables for one to ten days; others try it for longer. Many people turn to this type of fast after holidays or after a period of binging to detox.

Cleansing Fast

Feeding the body something to expedite elimination and dispose of toxins is commonly practiced by many people. Cayenne and lemon is one example of this, as is aloe vera.

Alternate Day Fast (ADF) 

This type of fast is often compared with IF in terms of decreasing the digestive load, but it is more in line with a calorie restricted diet leading to possibly more difficulty in adhering to it. With IF, athletes and those requiring a specific amount of calories can still obtain those within the 8 hour period.

Fasting Mimicking Diet (some use the product Prolon)

This provides low calorie diet, but focuses on nutrient dense foods, primarily vegetables, broths, and easy to digest carbohydrates for 5 days.  Studies by Dr. Valter Longo, a biogerontologist and cell biologist, show that a process called “autophagy” is induced with fasting, which stimulates the immune system to clear out damaged cells that are the least healthy, and also triggers the release of stem cells to produce healthier cells.  It is considered a “regenerative” diet.


Studies to Support Intermittent Fasting Benefits

Other than Dr. Dewey’s accounts of treatments for his patients nearly 120 years ago, there aren’t many studies done on humans alone in our time. Obviously more human studies need to be done, but the following are extremely promising. Most thus far conducted are on mice, rats, and fruit flies. They are still noteworthy in relation to the beneficial effects of IF.

Improved Cognitive Function

A vital protein called brain-derived neurotrophic factor (BDNF) helps to produce new brain cells and protects these cells from premature cell death. Studies show that a deficient amount of BDNF has been present in instances of impaired learning, depression, and even Alzheimer’s. Early studies show that Intermittent Fasting can increase levels of BDNF.

A 2014 study conducted on rats and published in the Journal of Neuroinflammation showed BDNF reduction was prevented and brain inflammation was suppressed in the subjects on a 30 day IF regimen.

Weight Loss

Initially, IF appears to be another calorie restrictive diet, and some people treat it as such, but one indication is that a benefit to IF-induced weight loss is that it is visceral fat being lost, and not just wasting muscle or water, as in a crash diet or prolonged illness.

One study compared 2 groups of healthy, resistance-training males over an 8 week period to find that those put on an IF diet (consuming three meals in an 8 hour period at 1pm, 4pm, and 8 pm) “showed a decrease in fat mass,” even though both groups measured the same in maximal strength and measurements of arm and thigh muscle areas. The IF group also showed “testosterone and insulin-like growth factor 1 decreased significantly” while there were no changes in either of those to the control group (who consumed 3 meals in a 24 hour period at 8am, 1pm, and 8pm)

Diabetes Prevention

Early studies have found that IF could aide in the prevention of Type 2 diabetes, according to an article published in the Journal of Laboratory and Clinical Medicine. When comparing calorie restrictive (CR) diets to alternate day fasting (ADF) and intermittent fasting, the CR subjects have more weight loss, but all three had a comparable visceral fat loss, and reductions in fasting insulin, and insulin resistance. Given that CR is a more difficult diet to adhere to and often not realistic in terms of lifestyle, this is optimistic for type 2 diabetes treatment and prevention. (5)

Improved Cardiovascular Health

The Journal of Nutritional Biochemistry published an article in March 2005 linking heart and brain health to both CR and IF diets. Rodents on IF diets had higher resistance to heart and brain damage after heart disease or stroke episode. This is linked to “reduced oxidative damage and increased cellular resistance.”(6)

Is Intermittent Fasting Worth Trying?

Preliminary studies (as well as a text more than a century old) point to the following resulting from IF:

  • Increased cognitive function
  • Weight loss/maintenance
  • Diabetes prevention
  • Cardiovascular strength

Giving our bodies a chance to digest, heal, and function optimally is the goal. With proper planning, the intermittent fasting benefits could be fantastic.