As far as the kidney issue, unfortunately, there are medical studies that say that it has been proven that very high protein diets can damage the kidneys. These were not tested on the Atkins diet however.

It should be noted that if someone is doing Atkins properly, they will not be eating a very high protein diet. Atkins is essentially 65% fat/ 30% protein/5% carbohydrate. This is not too much protein unless someone overdoes the protein ratio by trying to avoid eating fat.

The Protein Power diet addresses the protein issue more directly. It makes you calculate your minimum protein requirement so that you limit your protein to this amount which can deter someone from accidentally overworking their kidneys.

It is important to prevent kidney damage from high protein diets by drinking the recommended amounts of water and by keeping hydrated by taking daily potassium supplements. These two things are the most essential formula for protecting your kidneys.

Until actual long-term research is done on low-carb diet's effect on kidneys, we really won't have the definitive answer.