Nutrition 101 - Intermittent Fasting
What is Intermittent fasting?
Intermittent fasting is a fasting technique that involves dividing your days (24 hours) between periods of eating and periods of fasting.
It is more than just skipping meals. You choose to eat during specific periods and then fast in between. The idea behind intermittent fasting is to eat all the calories and nutrients you need during your feeding window and then fasting – aka not eating any calories, during the remaining fasting window.
It is not about starving yourself. When done right, it is an incredibly effective therapeutic approach that produces amazing results for weight loss and type 2 diabetes, and it can
even help slow aging, prevent cancer, and improve heart health. Starving and fasting are completely different. Starvation is the involuntary abstention from eating; starving people have no idea when their next food source or meal will come. This occurs during a famine, war, or when food is scarce. Fasting is the voluntary abstention from eating for spiritual, health, or other reasons. It is controllable. The terms should never be used interchangeably.
Fasting is really interesting, and it has been a newer path for a lot of patients. I grew up learning (even in medical school) that the ideal was three meals a day and two snacks - with breakfast being the most important meal of the day. Research is not really showing this. I am not sure if it was an economical motivation from the food industry or advertising, but we have to go with the science.
Fasting has been around for millennia. It was considered part of everyday life. It has no standard time – since it merely is not eating. For example, if you fast between dinner and breakfast the next day, about 12 hours or so, that is fasting. Where do you think the word breakfast came from – it means to break your fast. It is not a fad diet, rather an eating pattern.
Why is it good? What happens when we fast?
Without boring you all to death with a bunch of science, I'll list just a few of the things that occur:
Insulin goes down. Regularly lowering insulin levels lead to improved insulin sensitivity. Your body becomes more responsive to insulin. This is the opposite of insulin resistance which is the root problem of type 2 diabetes. Type 2 diabetes is linked to heart disease, strokes, Alzheimer’s disease, cancer, etc.
Adrenaline goes up and so does metabolism. You have more energy and mental clarity.
We burn fat, not sugar, therefore most people lose weight and fat.
Autophagy increases. This is a fancy name for our cells cleaning up their garbage. They are sort of taking out their own trash.
We become much more metabolically flexible. This is the ability to respond or adapt to conditional changes in metabolic demands. Metabolic flexibility is essential to maintaining energy balance in times of either caloric excess or caloric restriction and in times of either low or high energy demand, such as during exercise.
Resistance to stress improves, as does our mitochondrial functioning (these are the work horses of our cells).
Inflammation is decreased - Inflammation is tied to so many things including heart disease, cancer and dementia.
Different intermittent fasting methods
Time-restricted feeding. The 12/12, 14/10 or 8/16 (eat/fast) periodic fasting techniques are some of the most common. These are the least intrusive intermittent fasting techniques as they includes a feeding period of 8-12 hours and a fasting period of 12-16 hours. Most anyone can do a 12 hour fast- just don't eat after dinner, sleep, and then eat breakfast 12 hours after your last meal. The most popular is the 8/16 approach, as it is simple and consistent. Every day of the week, you eat for an 8-hour window of your choosing and then fast for the remaining 16 hours. For women, the eating window can be longer. So, the schedule is 10/14 (eat/fast.) The 8/16 system assumes that your diet is generally healthy and nutritionally balanced. It does not require specific dietary restrictions. In other words, the benefits of this fasting technique are largely due to the timing of meals. While a healthy diet will greatly improve your results, the emphasis is on the timing. You must stop eating at the end of your eating window. The advantage of this approach is that you can schedule the 16-hour fasting window to include sleep. So, you are only fasting for 4 hours before bed and 4 hours after you wake up. This is what I do most of the time. I usually fast 14-16 hours and eat the other 8-10. I do this just so I can get in all those macronutrients, micronutrients and phytonutrients I have been writing about. Otherwise, I don't think I am eating enough, especially protein. (I also do a 24 hour fast about once a month.)
Alternate-day fasting - 3-5 days a week. The basic idea is that you fast one day and then eat what you want the next day. This way you only need to restrict what you eat half of the time.
Periodic fasting or 1-2 nonconsecutive days of fasting. The 5/2 periodic fasting program is based on a much longer interval. The idea is to eat normally throughout the feeding days and then pick one or two days per week when you will fast for the entire day. You will fast during the entire fasting window of a full 24-hour period. Ideally, you would fast two days per week.
The beautiful thing about this is how many options there are for patients. We can individualize or tailor this based on the patient’s preferences and what is realistic for them. We are all genetically different and have our own circadian rhythms; it is great to be able to work with each individual and adapt it to something that they can make part of their lifestyle.
It’s simple, free, convenient, and powerful... AND you can still enjoy treats!
Who do I NOT recommend to Intermittent Fast? This is a very big caveat!
Those who are severely underweight, malnourished or chronically ill. Many time these patients are struggling to get enough calories, fat, and protein already. Cutting their eating window would make it even harder.
Children under the age of 18. They are growing and need the nutrition and calories.
History of or propensity for eating disorder. I am super cautious with these patients. You do not need to have something else regarding food and control to fixate on.
Pregnant or Breastfeeding. Again, you are feeding more than one person. Fetal development and infant nutrition are so important.
People that need to do it under the care of their doctor:
Anybody who is taking regular medications for conditions should consult with their physician, as some medications are best taken with food.
Diabetics, especially type 1. Careful monitoring of glucose is crucial.
Fasting is a stress on your body, and that is some of the reason it is beneficial. You have to look at each person individually at different times in their lives. A lot depends on overall health and adrenal health. This is where talking to your health care provider is so important.
The Importance of eating healthy
Of course, fasting isn’t a cure-all! Healthy eating still matters. I always tell my patients that “Food over Fasting”. You must eat health-ily. You cannot eat a bunch of crap. I know I am repeating myself!!! Look at all my previous posts!
Eat whole, unprocessed foods.
Reduce sugars and refined grains
Eat more natural fats and less artificial fats.
You have to stay hydrated during your fasting period. Water, black coffee, herbal teas, and homemade broths are all acceptable.
Understanding the rhythms of life
Fit fasting into your schedule, not the other way around.
If you know you have a dinner to go to that night with your friends, lengthen your fasting window so you can enjoy being with them. Avoiding all social situations during fasting is not healthy and will likely lead you to just throw in the towel and quit.
One of my favorite books on fasting and one I highly recommend is written by a nephrologist and is credible, evidence-based and sound. The Complete Guide to Fasting by Dr Jason Fung MD.
He has a couple of paragraphs in his book that I love!
“Celebrations with family and friends are integral to a life well-lived. Every once in a while, we need to remind ourselves that life is sweet, and we are lucky to be alive. And through human history, we have done that through feasting. The very act of eating is a celebration of life and when we celebrate important events, we do it with a feast. Any diet that does not acknowledge this face is doomed to failure. We eat cake on our birthday. We have feasts on holidays like Thanksgiving and Christmas. We prepare wedding banquets. We go to a nice restaurant on our anniversary.
We don’t celebrate with birthday salad. We don’t eat wedding meal replacement bars. We don’t gorge on green shakes on Thanksgiving.”
"There are times in your life that you should eat a lot. There are other times that you should be eating almost nothing. That is the natural cycle of life. When the harvest came in, they feasted. Bur they often fasted in the winter.
What has happened in the past fifty years or so is that we have kept all the feasting, but eliminated all the fasting. The normal balance has been perturbed, and obesity is the predictable outcome. If you feast, you must fast. That's all there is to it."
Well said!!! Enjoy your life. It is a balance. It is the only life you will ever have!
All material was gathered and researched through my amazing fellowship program, The Arizona Center for Integrative Medicine.
and
https://www.ifm.org
Fung MD, Jason & Moore, Jimmy.The Complete Guide to Fasting.Toronto, Canada. Victory Belt Publishing Inc, 2016.
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