Today, low carb diets are popular among people who want to lose weight fast and bodybuilders. The main philosophy revolves around a condition called "ketosis" -- a state in which fat is primarily used to fuel the body. Ketosis occurs when a person fasts, excessively exercises, or dramatically reduces carbohydrate consumption.

Consuming large amounts of carbs raises blood glucose levels, which are balanced out with insulin. But insulin also acts as a storage hormone, which conditions the body to store future carbs as fat in adipose cells in case of starvation. Furthermore, insulin also incites the cells not to release the stored fat.

Low carb diets prevent this. The less carbs you eat, the less insulin you produce. Low carb diets claim to allow their followers to eat anything they want, even fatty foods, because the body does not store fat on account of the aforementioned insulin fact. Simply put, since there are no carbs to use as fuel, the body burns fat.

Following the diet, one should eat between 10-60 grams of carbohydrates a day. Low carb diets base their claim on ketosis, but this state does not have to come exclusively from carb suppression. Exercising while following the low carb diet will help speed up the process.