There’s a new television ad for Bally’s fitness centers in which several clients give testimonials about their improved physical state. One such client states that he’s “lost 8 pounds of fat and gained 4 pounds of muscle”. How could one possibly know the ratio fat lost to muscle gained?
There is a caliper(sp) you can have done at a gym that measures fat and muscle. There is an electronic one too but it is not as accurate. The caliper is a pinching type apparatus that squeezed the skin on certain parts of the body arm, thigh, stomach and chest.
AFAIK, there are 3 ways to determine the percentage of fat. In order of ascending accuracy they are: (a) skin calipers, (2) bioimpedance, and (3) water immersion.
While that is true, I agree with ther OP that since all of these measurements are somewhat inaccurate, it would be hard to measure such a small gain/loss with lots of certainty.