Time Restricted Eating (a.k.a. Intermittent Fasting) and Fasting

When you eat the right foods, your health will improve; however, the best results are when you eat the right foods at the right times.

Suggestions on how to start

Step 1: Eat while the sun is up (no later than 7 PM)

Why?  The body becomes progressively more insulin resistant as the days go on so we store more of what we eat later in the day.

Step 2: Decrease your eating window i.e. Intermittent fasting (also known as time restricted eating)

Contrary to conventional wisdom, eating throughout the day often contributes to over-eating and disease.  Restricting your eating hours to a 6-11 hour window (or less) can dramatically improve health.   Women of child-bearing age should be less aggressive in restricting their eating periods.  Men and some individuals with significant health issues may benefit from a shorter eating window of 2-6 hours.   Generally, one should practice intermittent fasting only 5-6 days a week in order to ensure adequate overall nutrient intake and to prevent your body from adapting.  

When should you eat? While some studies show benefits with eating breakfast, this does not work for everyone. Other issues to consider are when your family eats together and when you are naturally hungry.   You definitely want to avoid eating after 6-7 PM as calories in the evening promote insulin resistance and inflammation.  

Why does just eating part of the day make a difference?  Why does it improve your health?  It keeps your insulin low and gives your body time to do some important maintenance work such as clearing stores of sugar and starts the burning fat process (i.e. making ketones).  Burning fat as your fuel source has wonderful effects on your health: lower glucose, triglycerides, inflammation and weight.  Eating less hours also allows our distended stomachs to return to a smaller size which helps normalize our super-sized American appetites. Once you have mastered intermittent fasting, consider moving on to some additional steps to improve your health.

Step 3:  Occasionally, eat just once a day

This is an advanced version of the above intermittent fasting, you may want to do this 1x/week.   When you eat only 1x/day it is really important to eat nutritionally dense foods like healthy fats (avocado) and the "G-BOMBS" Joel Fuhrman refers to: Greens, Beans, Onions, Mushrooms, Berries and Seeds.

Step 4: Water fast for 24 hours

While not eating for part of the day or even several days may sound extreme, keep in mind that water only fasting has been done safely for millennium.  Recently, numerous studies have been published showing fasting to be one of our best tools for staying healthy and even reversing disease. Fasting truly can be the fastest route to better health, fasting can improve your brain, heart, blood pressure, blood sugar, arthritis, inflammation, mood, autoimmune problems, migraines, allergies, cravings and more.  Even outcomes of cancer therapy are improved with fasting. 

People often skip this powerful "fountain of youth" because they assume it's too hard.  You will find options for water fasting as well as eating reduced calories that can be used in conjunction with many eating strategies including plant based, paleo and ketogenic.  Despite the safety of limited fasting, prior to fasting I recommend you have a discussion with your medical provider.

Fasting Produces Cellular House Cleaning (autophagy), Repair and Growth of New Cells    

Why does fasting make such a profound effect on our health and likely our longevity?  Fasting, as well as caloric restriction, promotes the ultimate cellular detoxification process referred to as 'autophagy.' Autophagy involves removing cellular debris which enables our body to work more efficiently, essentially act "younger."  Incredibly, fasting not only cleans out our cellular debris but it also stimulates our stem cells to gear up and start rebuilding and repairing our body (i.e muscle, brain, immune systems).  Finally, fasting also teaches our body to use fat for fuel, turning fat into ketones (ketosis).

If you do well with intermittent fasting for 18 hours, just add 6 more and try to do this regularly i.e. every 1-2 weeks.  Water is the ideal drink but if you regularly consume caffeinated drinks, drinking a small amount can prevent a headache.  You can also have Yerba Mate if desired.  Remember not to use juices, creamers or amino acid supplements as the goal is to actually be fasting.

Step 5: Short term fasting for 2-4 days

Note: we recommend you discuss this with your medical provider prior to fasting more than 24 hours and note that women of child bearing age should usually limit fasting to 24 hours 1x/week rather than longer periods. 

If you did well with a 1 day fast, you are ready to try going 2-4 days in a row for more potential benefits. Important tip, you want to be eating low carb when you try this so you your body will be adapted to using fat.  Make sure you tolerate intermittent fasting as well as a 1 day fast prior to trying the 2-4 day fast.  While fasting, it helps to exercise moderately to stimulate fat burning and preserve muscle mass.  By regularly fasting, your body's stem cells become activated which helps regenerate & rejuvenate your body (more muscle fibers and improved brain function).  I recommend you limit fasting to no more than 4 days per month. Interestingly, many find it is just as easy to fast 4 days as 2 because as you burn fat and make ketones, your appetite drops dramatically and energy often increases.  The 3-4 day fast can be repeated every 1-4 months. Note that fasting results in sodium and potassium loss, use water with sea salt to balance, see the final thoughts below.  

Not ready for short term fasting? Calorie Restriction Options

Option 1) Calorie restriction several times a week Studies have shown when calories are dropped every other day, health improves.  In the studies, men eat 600/women 500 calories every other day.  The non-calorie restricted days do not have any specific limits as how much is eaten or when, yet weight drops and labs improve.  Benefits can even be seen if calories are restricted to just 2x/week, the so called 5:2 plan.

Option 2) The "Fasting Mimicking Diet" is a well-researched, convenient, albeit, pricey plan which involves consuming specific reduced calorie meals packaged and sold through www.prolonfmd.com.   The 5 day FMD can be done every 1-4 months.    

Who should not fast?

A few groups should not fast, most are obvious: Individuals with an eating disorder (anorexic or bulimic), children < 18, pregnant/nursing women, those who are underweight, the extremely frail i.e. uncontrolled heart failure, severe kidney or liver disease.  Also, those with certain metabolic disease like porphyria, and disorders of fatty acid metabolism.  Individuals with Type 1 Diabetes generally should not fast as they need very strict supervision and monitoring. Those with type 2 diabetes can fast but if taking medications to lower blood sugar, these medications typically should be reduced or not taken while doing a water fast - discuss with your provider.

Final thoughts:

Fasting is a very powerful wellness tool and most reasonably healthy non-pregnant adults can do.  Women of child bearing age should be less aggressive in total water fasting – suggest no more than 24 hour fast per week and avoid longer fasts.  Most should limit water fasting to a 4 days/month (either in a row or spread out).  You should generally feel well during a fast.  During a 3-4 day fast, you generally would stay on your hormones and  hold off vitamins, unless you know stopping a vitamin will cause issues for you to stop (i.e. getting constipated off magnesium, fatigue off B vitamins).  Adding some sea salt to replace some of the electrolytes you can lose during fasting can help you address headaches or energy slumps (1/4 tsp to glass of water as needed or 1 tsp to 1 gallon of water).  If you have cramping, add potassium 99 mg 2 caps 2-3x/day. The extra energy you have doing a fast might make sleep a bit off, extra magnesium or melatonin can help.  Please use common sense here:  If you have an issue that does not resolve with more water/sea salt or bone broth, you should eat. For example, if you lose too much weight, experience weakness, lightheadedness or just generally feel bad add food back in. When you break the fast, start very slowly with soup or bone broth. 

For more information see:

Youtube videos

"Eat, Fast & Live Longer BBC Documentary.” 

Youtube channels: Eric Berg; Thomas DeLauer

Books on Chrono-nutrition, intermittent fasting and fasting:

"What to Eat When" by Michael Roizen

“Waist Away” by Chantel Ray – focus on eating windows (intermittent fasting) and fostering healthy eating attitudes and practices

“The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended" by Fung and Moore

"Fasting and Eating for Health" by Joel Fuhrman (note that Dr. Fuhrman includes information on more extended fasting beyond the scope of this article).  

Paradox Eating by Steven Gundry

The Longevity Paradox: How to Die Young at a Ripe Old Age

The Plant Paradox

Books on the Ketogenic Diet

"Ketotarian" Dr. Will Cole - a mostly plant based ketogenic plan

"The Ketogenic Bible" by Jacob Wilson & Ryan Lowery

"The Keto Reset Diet" by Mark Sisson and Brad Kearns


"Simply Keto" by Suzanne Ryan

"The Keto Diet: The Complete Guide to a High-Fat Diet, with More Than 125 Delectable Recipes and 5 Meal Plans to Shed Weight, Heal Your Body, and Regain Confidence" by Leanne Vogel