In the absence of carbohydrates the body burns fats in an inefficient manner producing toxic byproducts called "ketones." To wash these toxic waste products out of the system large amount of body fluids are expelled through urine, which is mainly responsible for the rapid loss of weight in the first few weeks of starting a low carb diet such as Atkins'. (Sachiko et al, 2001) The other reason for weight loss in low carb dieters is the loss of appetite associated with ketosis, which leads to lower total caloric intake. Weight loss may also occur because most dieters find low-carb diets relatively unpalatable in the long term and eat less calories. Hence, there is no 'magic' behind the weight loss in Atkins' Diet. Further, loss of weight through loss of fluids and loss of appetite is neither desirable nor sustainable in the long-term as the body regains water and appetite rapidly as soon as normal diet is resumed.

There are a number of adverse health-effects which can follow a severe unbalancing of diet such as recommended by Atkins. The American Heart Association (AHA), for example, points out that most Americans already eat more protein than their bodies need. It warns that high-protein animal foods (recommended by low carb diets) are usually also high in saturated fat, and their consumption for a sustained period "raises the risk of coronary heart disease, diabetes, stroke and several types of cancer." ("High Protein Diets," 2001) The AHA also points out that a