I have a “body composition” measuring scale. In fact, it provides estimates based on measurements of electrical impedance. I don’t take the estimates as gospel, but I have tracked them for nearly five months, and done some basic statistical analysis of these figures.

In my case, (I’m male, 50 years old, 179 cm) I’ve gone from 90 kg at the start of February down to 79 kg (as of last week), and my estimated %BF has decreased from 28% to 22%, a reduction of slightly more than 7 kg of fat and 3.5 kg of non-fat weight. I say non-fat, as my scale does not provide and estimate of lean tissue or muscle mass. A fair bit of the non-fat weight is water, but I would be surprised if I have not lost a couple of kilos of muscle.

While there is some reason to believe that IF may do a better job of sparing muscle than most forms of calorie restriction, it’s nearly impossible to lose significant amounts of body fat (through diet) and not also lose muscle.

I’m tinkering with my overall diet and slowly adding in some strength training in an effort to arrest, and eventually reverse, my lost of muscle mass. However, I am certain that it continue to fall somewhat while I continue to lose fat. Mostly I’m trying to get fitter, so that I’ll have good habits and a good base fitness from which to start rebuilding whenever I decide that it’s time to stop losing fat.

I began with a goal of 75 kg, but I think that I’ll still be well above 15% body fat when I get there in a month or so. Consequently, I’m now beginning to think that I will try for 70 kg, but it is a very soft goal. I’m just going to keep doing what I have been doing and monitor how I look and feel, as well as the various biomarkers that my GP has supplied.

You mileage *will* vary.