What is Intermittent Fasting?

Intermittent fasting is an eating pattern that creates long fasting periods which helps with weight loss and offers many other health benefits as well.

What happened to eating frequently throughout the day?

For many years, we all gobbled up the idea that we need to eat 6-8 small meals a day in order to maintain a healthy weight and “keep our metabolism up”.  It didn’t take long to realize that for most people, eating all day long simply does not help one maintain a healthy weight; quite the opposite occurs, actually.

Let’s think about it.  Our bodies are efficient machines.  They don’t like doing things that use up more energy than they have to.  This is a quality of most surviving species on Earth.  Our bodies are designed to store excess energy as fat so that when there is a famine, we have a way to survive.  Our bodies protect this stored energy and consider using it only as a last resort. Additionally, burning fat requires energy to be used, which is inefficient for the body.  So our body really doesn’t want to burn fat.  Eating frequently provides a flow of calories to our body throughout the day.  Our bodies happily utilize these calories, and the need to burn its stored fat is eliminated.

Let’s take a slightly deeper look at this.  When we eat food, especially foods that are high in carbohydrates, our bodies secrete insulin in response.  Insulin is a storage hormone.  It tells our body to store the energy we’ve just eaten and tells our body not to burn fat.  When we are in this “fed state”, we have insulin flowing through our body, putting us in “storage mode” and unable to burn fat.

When we are fasting, however, insulin is not secreted.  It is sleeping soundly in our pancreas.  Thus, if we are needing energy and we are in the fasting state without insulin, our bodies are able to burn fat for the energy we need.  You can see, then, that in order to burn fat, we need to have fasting periods throughout our day.

How do I do it?

Intermittent fasting means that you choose certain periods of time where you fast.  While fasting, you do not consume any calories at all, liquid nor solid. There are several types of intermittent fasting.  The most common types are:

• The 16/8 type of intermittent fasting involves fasting for 16 straight hours per day, every day. You have an 8-hour window in which you may eat. You should eat healthful foods and drink 64oz of water daily.
• The 5:2 method involves eating regularly for 5 days out of the week, and fasting for 24 hours two days a week. For example, on Monday and Thursday you take in only water; no calories liquid or solid at all from midnight to midnight. On the other days of the week, you eat a healthful diet.
• Alternate Day Fasting is another method. It entails fasting every other day.

What are the benefits?

Intermittent fasting has many health benefits.  In addition to weight loss, benefits are also seen for diabetes mellitus, cardiovascular disease, cancers, and neurologic disorders.  Intermittent fasting helps our mental and physical health and improves our ability to resist disease.

In animal studies, mice on alternate day fasting programs had better running endurance than those on an unrestricted diet, even when they were of similar weights. Animals on time-restricted feeding and alternate day fasting demonstrated superior balance and coordination than those on an unrestricted diet.

Will I be hungry?

Studies have shown that hunger is not decreased on the 5:2 or Alternate Day methods of intermittent fasting, but it can be decreased by time-restricted eating, specifically when the eating window is early in the day, with the last calories consumed by 2:00pm.

A study done by Ravussin, Beyl, Poggiogalle, Hsia, and Peterson at Pennington Biomedical Research Center demonstrated that patients using the intermittent fasting 16:8 method with early eating hours from 8am to 2 pm showed decreased ghrelin levels.  Ghrelin is a hormone that is responsible for our sensation of hunger.  Those patients reported a decreased desire to eat and an increased sense of fullness.

What is the history of intermittent fasting?

The concept of Intermittent fasting goes back for ages, but in reality, it has been around forever.  In our days as hunters and gatherers, we ate when there was food, and we fasted when we didn’t.  It is a more natural approach to eating than our regimented mealtimes.  It became popular as an eating plan in 2010’s with the book The Fast Diet by Dr. Michael Mosley, The 5:2 Diet by Kate Harrison, and The Obesity Code by Dr. Jason Fung.  People started trying it and had good results, and thus the movement grew.

Recommended Diet for Intermittent Fasting:

• Choose lean proteins, including poultry, white pork, lean red meat, fish, eggs, soy, and dairy
• Make vegetables 50-60% of your diet. Choose the darkest colored vegetables and a wide variety.
• Eat some fruit, but not large amounts, as they contain high amounts of sugar. Limit to 1-2 servings per day.
• Consume small amounts of healthful fats, including avocado, olive oil, olives, nuts, seeds, and fatty fish like salmon
• Choose whole grains such as barley, farro, and quinoa instead of processed foods like bread and pasta.

Tips for Intermittent Fasting:

• Choose the earliest time frame possible for you, such as 8:00am – 2:00pm, to minimize hunger.
• Avoid liquid calories. Choose healthful foods that will help with satiety.
• Drink 64 oz water daily. Maintain adequate hydration to minimize false-hunger signals.
• Minimize caffeine to 1-2 cups/day to minimize dehydration.
• Limit artificial sweeteners to avoid stimulation of insulin release and increased sweet cravings.
• Avoid eating while reading, working on the computer, or watching TV. Make your eating mindful.  Eat only to satisfy hunger.
• Exercise at least 30 minutes a day with components of both aerobic and anaerobic exercise. Don’t overdo it.  Excessive exercise can increase your appetite.
• Have a good support team. Practicing intermittent fasting with a partner can be very helpful.
• Even during your eating window, don’t eat constantly. Fast in between your meals.

Intermittent fasting is a lifestyle and eating pattern that shows many health benefits.  For more information or support, contact Sage Bariatric Institute, whose multidisciplinary team and obesity specialist doctors can support you on your journey.

Resources:

Effects of intermittent fasting on health, aging, and disease. de Cabo R, Mattonson MP. New England Journal of Medicine, December 2019.

Metabolic Effects of Intermittent Fasting. Annual Review of Nutrition, August 2017.

Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metabolism, May 2018.

Intermittent fasting: Surprising update. Tello, Monique MD, MPH. Harvard Health Publishing, June 29, 2018

Early Time‐Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans. Obesity, 24 July 2019.

Sage Bariatric Institute Website: www.sagebariatric.com