Weight Loss while Fasting

So, just how much weight should you expect to lose while fasting? I hear that question from a fair number of people, so I although it will be a short article, I thought I’d answer that question today.

According to Dr. Jason Fung, whom I consider to be the world’s leading expert about fasting for medical purposes, you should lose about a half pound of fat per day while fasting.

A lot of people think the weight loss will be a lot more than that, but I find that number to be fairly accurate. Weight loss that you will sustain is usually about half of a pound per day. Sometimes I lose significantly more than that in a day, sometimes I even gain a little while fasting. The difference, I believe, is the water fluctuations in your body. With my Tanita Body Composition Monitor I can see the daily fluctuations in water in my body, and the more water you retain, the more your weight will be, of course. Having water in your body is not a bad thing… in fact, if all of your water was gone you’d be dead, so don’t worry about it! Just keep in mind that if you gained a little weight one day, that does not necessarily mean you have more fat!

When you fast, you will usually lose significant weight after the first day, and a fair amount after the second day. But when you are fasting, your body generally releases a fair amount of water, which means you lose more on those first couples of days. For example, in my current fast, I lost 3 pounds after day 1. However, you should expect that after you start eating again, that water loss will return. So, for example, let’s say that you fast for 10 days, and your total weight loss is 10 pounds. That is 1 pound per day! But, after you eat for a couple days, you will probably gain back 4 or 5 pounds, which is all water. So, your actual fat weight loss at the end will be more like 5 or 6 pounds, or, as Dr. Fung says, about a half pound of fat loss per day.

I would say that over the past, I have probably lost slightly more than a half pound per day while fasting, but less than a pound per day. Not significantly more, but maybe .6 pounds per day instead of .5. Perhaps the reason is that I had so much weight to lose, I can’t say.

Overall, though, I would say that Dr. Fung’s estimate of weight loss is pretty accurate, and it is what you should expect. Don’t get discouraged when you gain back that water weight after the fast is over, that is just natural.

Keep on fasting!