New Intermittent Fasters: Pushing through a Tough Spot

If you hit a rough spot a few weeks into fasting, stick with it. If you can push through that adjustment phase, everything good is on the other side.

Here’s a common pattern I see in beginner fasters. Many people who start slow with something like 16:8 find the first week of fasting relatively easy. However, as they near the end of their first month and they are increasing their fasting a little more, they often hit a rough patch.

There’s a biological reason for this. I’ve mentioned before that the liver can store between 12-24 hours worth (depending on factors such as how active you are) of temporary, easy-access glucose in the form of glycogen. As you transition to eating two large meals instead of three and focus on high protein instead of high carb, your liver glycogen will slowly decrease and you will eventually run out.

So let’s suppose that in week one you start out with your liver glycogen at 100% and each day you fast for 16 hours, you’re burning through about 60% of what’s available during the fast. Then when you eat on day one, you only have enough carbs to go back to about 90% capacity. By the end of week one, your liver glycogen right before you eat is now dropping to 30% and you’re refilling to only 75%.

If this trend continues and you keep eating fewer carbs (fat and protein do not contribute to liver glycogen), you’ll eventually run out of liver glycogen during your fasts. When happens, you will feel it and usually fasting will get a harder for a time.

I want to assure you that if it stayed as hard as it feels during that transition, then nobody would do it long-term. But after you conquer this adjustment phase, everything begins to get easier.