What is heavier: a ton of feathers, or a ton of bricks?

They're both a ton, so they're both the same weight. Well, a pound of fat weighs the same as a pound of muscle. It's logical. A personal trainer dispels the gym myth about replacing lost fat with muscle and answers the question I hear so often as a marathon/half marathon walking coach:

Why Doesn’t Exercise Always Affect Body Weight?

TUESDAY, April 1 (HealthDay News) -- Despite appearances to the contrary, more than half of normal-weight Americans have a high percentage of body fat. And, like their overweight contemporaries, this makes them susceptible to heart disease, diabetes and other metabolic disorders, a new study says.

Men whose body fat is greater than 20 percent and women whose body fat is greater than 30 percent are suffering from "normal weight obesity," the study authors said, even though their weight may be normal for their size.