I received an email like the one below a couple days ago and thought that it might be helpful to some here. Sometimes the really basic stuff gets left behind…
Question: I’ve had an eight lb. gain of fat or muscle, in short period on a new book’s diet program…
Answer: I cannot give specific health-related advice to you for liability and responsibility reasons. I can say, just as general information, that the scale can be misleading when weight training is involved. Although even a few pounds of muscle take several weeks to build, it can certainly add to one’s body weight.
A technique like use of the skinfold caliper can help athletes determine whether weight gain is fat (more millimeters in a man’s abdominable “pinch” or combined chest+ab+thigh “pinches”) or if it is indeed likely to be muscle (weight gain and new upper arm size without changes in the total mm of skin folds).
But skin folds are just a gross estimate, even in the hands of a well-practiced technician. (Those who have done fewer than 50 whole body analyses aren’t properly trained.) You may want to do an Internet search on “body composition” or “skin folds”.
(There’s much more to skinfolds than what I’ve written. I believe it’s a best choice among body composition tests for consumers.)