Retaining your muscle mass while on a weight loss program is one of the most important aspects that you need to concentrate on as this will help you to keep your fat percentage down long-term.

On the ultra low calorie diets the body begins to cannibalize its own muscle tissue as its defense mechanisms come into play.

An example of this is shown with some of these apparently slim fashion models who have quite high levels of body fat in proportion to their overall size.

The reason for this is the fact that they haven't done any form of exercise or resistance training to maintain any reasonable level of muscle mass and this is only made worse by the fact that they are often eating a very low quality diet and nutrition is lacking.

It is not uncommon to see skinny models with cellulite and that is a sure sign that they are retaining fat in a higher percentage than they should be.

They would find that if they added a little bit of resistance training or even some form of decent exercise to their daily routine they would be able to still retain a slim figure but the body fat percentage would be considerably lower and they would look a lot more toned and healthy.

And healthy is what you should be aiming for when you go on a weight-loss program and not simply losing weight as actually improving your overall health and well-being will help you to live a better lifestyle for a lot longer.

Increasing your muscle mass also improves your metabolic rate whereas body fat has a very low level of metabolic activity. Nutritionists regard muscle as the furnace that burns in the body and this is what you should be aiming for.

If more weight loss programs focused on retaining muscle mass people would be unlikely to put the weight back on rapidly once they finished the program.