There is a difference (or shall I say --distinction) that should be made between some of the terminology used to describe "building muscle" mass and "toning" your muscles.
The term " tone " is thrown around a lot and seems to mean different things to different people.
Exercise with weights can build muscle mass and or "tone" your muscles.
What does it mean to "tone" your muscles? Muscle "tone" has to do with how contracted your muscle stays when you relax. When you're out of shape, you have poor tone and your level of contraction when at rest is low...your abs and arms and legs look "mushy" even if they're thin.
When you're in shape, you have good tone and your level of contraction when at rest is high. You can be toned without having to add a lot of muscle mass. And don't confuse looking " toned" with looking "lean" (i.e lean as in where you muscles are very obvious) which is a matter of losing body fat. For example, having a 6-pack of abs is all about losing fat (and toning ab muscles) - not muscle mass.
This is why getting your body fat down is a key part of getting a " toned " muscle. Remember fat is not only just under you're skin but (if you have a lot it) it's riddled throughout your muscles like the 'marbling' or fat you see in a steak. If you want your muscles to to 'taut' and 'toned' and you want nothing but muscle,you have to get rid of the 'marbling' by burning the fat IN YOUR MUSCLES as well as the fat on top of your muscles ...and usually the best way to do this is via weight training , a good diet and some form of cardio.
Muscle loss from dieting usually occurs when the calorie deficit is significant enough such that your body thinks it's approaching some form of starvation period. In response, your body makes it a priority to actually conserve more fat and instead of burning fat for energy as it normally would, it turns to other sources of energy....namely, amino acids (usually reserved for lean tissue synthesis - i.e building / maintaining muscle) which are now being converted to energy.
Muscle loss from prolonged cardio over days/weeks can also occur in situations where glycogen stores are not replenished enough over time to meet training demands and - as in the other example - your body turns to cannibalizing muscle protein for use as energy. This is why you see some long distance runners who train with longer cardio sessions over time having very little muscle on their upper bodies, sporting that "emaciated" look.
After losing 40+ unwanted lbs:
Last edited by Chillen; 04-24-2012 at 07:23 PM.