To fast or not to fast? Fasting has quickly become a popular health and fitness trend that is helping people lose weight, improve overall health and reverse type two diabetes, sign me up! Don’t just take my word for it (though I did reverse my diabetes through a combination of a low carb diet and intermittent fasting), studies have shown that it can have many benefits on your body and mind. It’s possible that it may even be the secret to longevity.
The thing is, fasting is far from being a new concept. People have fasted through the ages, and it was probably quite common for our hunter and gatherer ancestors to fast for days as they searched for food or came across unfavorable situations. In recorded history, many of history’s greatest philosophers and prophets were big advocates of it. Jesus, Buddha, and Muhammad all believed in the healing power of fasting. The scriptures are littered with fasting as a means to cleanse the body of illness and for spiritual reasons. It was seen as something intrinsically beneficial to the body and spirit, and is still practiced in religions around the world.
Hippocrates, largely considered the father of modern medicine, believed that, “Everyone has a doctor in him or her; we just have to help it in its work. The natural healing force within each of us is the greatest force in getting well. Let food be thy medicine and medicine be thy food. But to eat when you are sick, is to feed your sickness.” He refers to the natural urge inside of us that refuses to eat, or can’t bear to eat, when we’re sick. Our bodies developed this instinct as a means to heal themselves, an instinctual fast. Benjamin Franklin said, “The best of all medicines are resting and fasting.”
Fasting is a form of medicine, but a medicine for what exactly and how can it help you?
Fasted and Fed States
Our bodies are perpetually in one of two states, the fasted state or the fed state. When we eat food, our bodies release insulin and we go into storage mode, the fed state. We store glucose, sugar, in the liver and muscle cells first, but as those fill up and they fill up quickly, we store the extra sugar into fat cells. In the fasted state, we do the opposite. Our bodies pull sugar and fat from cells and utilize it as energy. That’s why we save the energy in the first place, it’s our energy reserve. This is a very normal process, and we evolved to survive without food for hours or days without any negative health consequences.
The problem though, is that it takes time about 12 hours after our last meal for the body to enter a fasted state. If you eat a regular breakfast and dinner, then your body is in the fed state, storage mode, for most of the day. You never end up burning what you have stored, and live off of the food coming in which will eventually lead to weight gain. Worse yet, in the fed state, you have elevated levels of insulin and if left unchecked, you may become insulin resistant. Learn more about insulin resistance here.
Intermittent fasting is simply a way to use that stored energy, and for all my type two diabetics out there, a way to lower your resistance to insulin. Note, if you are on medications, you’ll need to speak to your physician before starting because you’ll probably need much less medicine to avoid hypoglycemia.
Benefits of Fasting
There are many benefits to fasting, the most obvious and proven are weight loss, fat burning, lower insulin levels, and decreased insulin resistance. Fasting is also simple, doesn’t cost you any money, is flexible - cheat meals are easier to work in, adjustable - you can fast longer, and can be added to any diet. The following are all potential benefits of fasting but they need to be studied in more depth, though I can personally attest to most of these:
Reversal of type two diabetes
Improved mental clarity and concentration
Increased growth hormone, though it takes a much longer fast (days vs hours)
Improved blood cholesterol profile
Reduction in the risk of Alzheimer’s disease
Longer life (yes please)
Cellular repair and cleansing through autophagy, cell digests old and unused parts
Reduction of inflammation
How to Intermittent Fast
Fasting can be done a number of different ways and different people have popularized different styles of intermittent fasting. I’m going to cover the basic ones, but they can generally be broken up into two categories, short (<24 hours) and long (>24 hour) fasts. Longer fast will typically require medical supervision.
The 16/8 Method - You intermittent fast for 16 hours straight and eat all your meals in a window of 8 hours. Breakfast is typically skipped and most people start at lunch and go through dinner. Its a matter of preference. You will eat about the same or less than you would normally eat, so you also benefit from slight caloric restriction.
The Warrior or 20/4 Method - Inspired by Romans and Spartans, this fast lasts for 20 hours and your eating window is reduced to 4 hours. This is typically just one giant meal in the evening.
The 5:2 Fast - This fast calls for 5 days of regular eating with two non-consecutive days where you only eat 500 calories. You can eat the calories in any way you choose - throughout the day or as a single meal.
The 24 Hour Fast or Eat Stop Eat - This intermittent fast is done by not eating for 24 hours, typically from dinner to dinner or lunch to lunch. You space it out and only do it two or three times a week.
36 Hour Fast - This fast is tough, you skip an entire day’s worth of food and pick it up again the following breakfast. It does however provide a more powerful weight loss benefit.
Longer fasts exist but should be done with caution. There is technically no real limit to how long you can fast. However, there are certain people that may need medical supervision during a fast. People who:
Are on prescribed meds
Have serious medical conditions like liver, heart or kidney disease
You should absolutely NOT fast if:
Have an eating disorder
Are pregnant or breastfeeding
Are a child under 18
Common Myths and Questions About Intermittent Fasting
There are many myths about what fasting is and isn’t. Won’t fasting…
Put me in starvation mode?
Make me lose muscle?
Deprive me of nutrients?
If our bodies were so poorly adapted to one day of fasting then our species wouldn’t have made it very far. Our bodies are designed to burn sugar first then fat. If we went without food in the wild and our bodies started eating our own muscle tissue for protein, wouldn’t we then be too weak to hunt and gather? You preserve muscle and bone until the end, and the secretion of human growth hormone ensures that your lean body mass does not suffer. You’ll burn sugar, fat, and use up your nutrients, that’s the whole point! :D
Here are the most frequently asked questions about intermittent fasting:
Can I exercise during a fast? Yes, you can. Just be sure to hydrate.
What can I have while I fast? Black coffee, tea, or water. No calories of any kind.
How do I deal with hunger? Hunger comes in waves, ride it out with a tea or coffee and keep your mind busy. Hunger will generally increase the second day and then disappear afterwards for long fasts.
How do I break a fast? Eat a regular meal, there’s no need to gorge as that's a good way to get stomach aches.
Will fasting slow down my metabolism? Quite the opposite. Short fast actually increase metabolism.
Fasting can and will most likely help you lose weight and improve your overall health if you stick to it. It’s all based on when you eat not what you eat, but don’t be fooled, you can’t just eat junk food and expect to see substantial changes. Food quality is and will always be important, I personally follow and recommend a low carb diet in line with the 16/8 method of fasting. Remember to be mindful about what you eat, and pay attention to your body’s response to the food you eat. For more on mindfulness, check out our previous blog.