I will give you a little more detail:

First time, I just wanted to fast for 3 days. But after 3 days, I felt great, so I kept going. I stopped after 7 days, not because I was hungry, but I just was bored with not eating (not a good reason, but that was why). During this time, I did not exercise at all because I thought I might be somehow using "too much energy."

Also, this was zero food, only water, and then only when I felt like I needed it, so mostly dry fasting.

I used an online bodyfat calculator, which takes weight and waist measurement to calculate lean weight, fat weight, and bodyfat percentage. It might not be the most accurate tool, but it is quick and easy and free to do it, and as long as I am consistent with my method, I figured it was good enough to know what was going on with my body.

Results:

Fast: 7 days Total Weight: -15.0 lbs Lean: -12.08 lbs Fat: -2.92 lbs Bodyfat: +0.40%

Months later, I started wondering what would happen if I did the same thing, but this time did a fullbody, brief workout, every other day.

Results:

Fast: 7 days Total Weight: -15.0 lbs Lean: -8.97 lbs Fat: -6.03 lbs Bodyfat: -0.70%

Finally, I wondered what would happen if I did my workout every day during the fast. Unfortunately, I had a last minute change of plans and had to go out of town, so I ended the fast after 4 days. But there are some interesting results, nevertheless.

Results:

Fast: 4 days Total Weight: -9.2 lbs Lean: -4.67 lbs Fat: -4.43 lbs Bodyfat: -0.80%

Notice, in 4 days, the bodyfat loss was equal to the lean loss.

Also, when I did not workout at all, the drop in bodyfat was fairly steady during the 7 days.

But when I did the 2nd experiment, the bodyfat drop was quick during the first 4 days or so, and then less so after that.

This is consistent with the 3rd experiment, where the first few days had a very sudden drop, but then I stopped.

Also, "lean" means everything that is not fat is included in the lean. That means that water weight is included in the "lean." Since I lost 4+ pounds of "lean" in 4 days, that might have merely been water and I might have actually maintained all lean. But I can't be sure because I did not use a more sophisticated scan to measure. IOW: That 3rd time might have been 100% fat loss with no lean muscle loss, but only some fluctuation in water.

I suspect this might be the fastest and healthiest way to lose excess bodyfat, but it is an aspect of fasting that nobody seems to know about.

An optimal strategy might be a series of 3-day fasts, lifting weights every day (7 days per week), and eat one meal every 3rd day (72 hours), and then repeat that process. Maybe even don't workout on that Day #3.

Anyway, I found it suprising and interesting.