A lot of people believe that high protein diets with low carbohydrates are the way to obtain lean muscle and lose weight.  Here is a molecular example of how low carb diets are bad for you and what they do to your body:

-NH2 with H-C-R and -COOH is primarily an amino acid  (a protein) ---->  -NH2  +  HOC=O (carboxyl to get glucose)  +  C5H4N4O3 (Uric acid)  ---> NH2C=ONH2  (urea) + H2O

The nervous system feeds off carbohydrates so it extracts it from proteins because it has no choice with a low carb diet. 

In order for this happen, the -NH2 breaks off the amino acid and the body is able to extract glucose from the amino acid.

The problem is that the metabolic cost for this action is ammonia and uric acid.  These products negatively affect the liver and  the kidneys.  These are two carcinogens that affect two major vital organs. 

Carbohydrates accelerate cellular metabolism  in order for fat cells to be used for energy.  Eat carbohydrates and you will aid your body in boosting your metabolism.  But remember you have to be active somewhat for your cells to be active.  Just eating carbs and being lazy will just result in slower cell metabolism.