The simple answer is - imagine someone who is working out regularly and someone who isn't.
The person who work out regularly may have more muscles than the other one, but at the same time, he has a worse genetic predisposition for muscle gain. The guy who does not work out on the other hand, has a better genetic predisposition for muscle gain, yet does not work out.
This is how our environment can influence muscle structure.
Answer:
The main reason for including this label is so consumers can be informed when making dietary decisions. For example, a "Hamburger Helper"-type box meal may say it only has 400 calories per serving as packaged.
