Fasting: A Case in Self-Experimentation

One of my favorite quotes is “necessity is the mother of invention." I have no idea who came up with it, but if you think about it, it certainly rings true. When a need becomes present, human beings will find a way to get something done. Fasting has been a part of world culture for eons, but it’s recently become a popular method for weight loss in western diets. I’ll tackle some of the science behind the reasoning for and against it in this blog post.

Why it might work: Fasting is something early humans had to deal with. You can imagine being a caveman or hell even an early settler in colonial days and not knowing when your next meal was going to come. Fasting became a part of human DNA, and thus, we evolved with a mechanism that allowed us to survive it. When you fast, and to be clear I mean roughly 8+ hours without any kind of food, your brain sends a signal to your liver to make glucose. Your brain needs a certain amount of glucose to function at all times. Should you not have any, your liver will use either your fat or muscles stores as a way to make more glucose. This is particularly ideal if you’re trying to lose fat. If you’re trying to put on muscle, however, it makes it a little tricky as we have NO idea as to where your body is pulling the glucose from first. But, either way, your liver makes more glucose and now your brain is happy and prepared to sustain functionality for a few more hours.

There’s no real book on when to allow yourself to eat when you are practicing fasting. Should you try to fit the majority of your eating into a 4 hour, 6 hour or 8 hour period? Who knows? I say the best thing is to find what works best for your schedule depending on when you can get some food. The one thing you do need to consider when fasting is that the first time you do eat should ABSOLUTELY be a balanced meal. I would say roughly 40% of the calories coming from carbohydrates, 30% from protein and the last 30% from fat. If you are to eat a meal that is primarily carbohydrates, you will basically shoot your fat-using process in the foot, as you will spike your insulin and immediately store the excess glucose that gets left floating around in your bloodstream.

Why it can be dangerous: The human body is by far the best thing in the world at adapting to whatever signals you may be sending it. This is both a good and bad thing and unfortunately for those of you looking to drop significant pounds of fat, fasting may make it adapt in a negative way. When we fast, our brains start instructing our livers to make glucose as we stated earlier, however, it also begins to prepare your pancreas to do its job much better. Your pancreas is responsible for releasing the hormone insulin into your bloodstream in order to remove excess glucose. The response you always want when releasing insulin is that of a normal heartbeat. You know, just like a little blip on the screen comes up and it goes right back down. It goes up just slightly when you eat something and then again goes right back down.

Well, as you begin to fast your brain tells your pancreas, “Not sure when something else is coming in so when it does make sure you really store it to our fullest potential.” Fasting can raise your insulin sensitivity, which is not a good thing. Your brain needs to ensure you have that backup generator to provide it with glucose whenever it needs it. If you start to fast, it’s going to ensure that you really fill up that backup generator, no matter what you eat. So, you take a day off from fasting and have some normal-sized meals all throughout the day, that glucose is getting stored in a hurry. If you are already vastly overweight, I strongly recommend an insulin sensitivity test before you begin implementing it.

If you have further questions, feel free to email me at jobie@crossfitvirilis.com, or come see us!

Jobim Zapico