"One of the possibly side effects is decreased kidney function from the rapid increase of proteins in the diet (which don't metabolize very cleanly compared to fasts or carbohydrates). People with kidney issues or possible problems should avoid these diets." You are confused and incorrect on this point at least, I recommend anyone considering this to go to some legitimate sources of information. There is a liver condition that is unrelated to ketogenic diets which people confuse mightily.

Nope, I'm definitely correct on this point. There's an unbelievable amount of bullshit in ketogenic diet circles about it - to the point an absurd reverse of well researched results. It's one of the very well researched downsides of any low-carb, high protein diets. The trick is to eat low-carb and low-protein as high-protein diets simply aren't good on kidneys. But then you're basically just eating fats and that gets boring. It's very hard to get dietary fats without one or the other though.

https://en.wikipedia.org/wiki/Ketogenic_diet

http://site.matthewsfriends.org/uploads/File/StonesPolycitra...

http://www.webmd.com/diet/high-protein-low-carbohydrate-diet...

"By restricting carbohydrates drastically to a mere fraction of that found in the typical American diet, the body goes into a different metabolic state called ketosis, whereby it burns its own fat for fuel. Normally the body burns carbohydrates for fuel -- this is the main source of fuel for your brain, heart ,and many other organs. A person in ketosis is getting energy from ketones, little carbon fragments that are the fuel created by the breakdown of fat stores. When the body is in ketosis, you tend to feel less hungry, and thus you're likely to eat less than you might otherwise. However, ketosis can also cause health problems, such as kidney failure (see below)."

"What Are the Risks Linked to High Protein, Low-Carb Diets?

High protein, low-carb diets can cause a number of health problems, including:

Kidney failure. Consuming too much protein puts a strain on the kidneys, which can make a person susceptible to kidney disease. High cholesterol . It is well known that high-protein diets (consisting of red meat, whole dairy products, and other high fat foods) are linked to high cholesterol. Studies have linked high cholesterol levels to an increased risk of developing heart disease, stroke, and cancer. Osteoporosis and kidney stones. High-protein diets have also been shown to cause people to excrete a large amount of calcium in their urine. Over a prolonged period of time, this can increase a person's risk of osteoporosis and kidney stones. A diet that increases protein at the expense of a very restrictive intake of plant carbohydrates may be bad for bones, but not necessarily a high-protein intake alone. Cancer. One of the reasons high-protein diets increase the risks of certain health problems is because of the avoidance of carbohydrate-containing foods and the vitamins, minerals, fiber, and antioxidants they contain. It is therefore important to obtain your protein from a diet rich in whole grains, fruits, and vegetables. Not only are your needs for protein being met, but you are also helping to reduce your risk of developing cancer. Unhealthy metabolic state (ketosis). Low-carb diets can cause your body to go into a dangerous metabolic state called ketosis since your body burns fat instead of glucose for energy. During ketosis, the body forms substances known as ketones, which can cause organs to fail and result in gout, kidney stones, or kidney failure. Ketones can also dull a person's appetite, cause nausea and bad breath. Ketosis can be prevented by eating at least 100 grams of carbohydrates a day."

There's tons more. But I can't be bothered right now.

That's with respect to high protein diets, and not necessary to keto, which is typically a medium protein, high fat diet. I'm also not certain an uncited webmd link is the best nutritional reference.

Seriously, if webMD is getting canned as a fringe site these days with inaccurate medical information and nothing to counter their medically accurate information, then there's literally nothing you can trust on the internet.

It's literally the accredited health care information site.

I'm not saying that their information is free from being wrong, just that given a standup between webMD and some random keto blog, I'll go with webMD.

Regardless of the source of dietary calories, a diet that triggers ketone production, which is the point of a ketogenic diet, introduces ketones into the bloodstream, which are processed in the kidneys.

Because there appears to be at least 2 people on HN who don't know about ketones (a family of organic compounds that includes acetone), but know about ketogenic diets, a well known and researched diet intended as a medical aid for epilepsy in children with a wealth of academic research on the effects of the diet both positive and negative. But it's also used widely to treat type 1 diabetes. Since diabetics often have reduced kidney function, ketone management can become critically important.

We know that ketogenic diets stress kidneys. This is basic information known to medicine. It's about as basic anatomy.

Other well known side effects include bone demineralization, constipation (which increases risk for colorectal cancer and other lower digestive complications), menstrual irregularities in women, increased colestrerol (up to 30%!), kidney stones are recorded at rates as high as 1 in 20, acidosis and all that includes.

It's considered as a diet that you should only go on under doctor supervision and constant blood tests.

Anecdotally

I've gone on keto 3 times, for different periods of time, and after being off of them for a month or so, I've developed kidney stones.

I have no idea if they're related, but I am the only one in my family that gets them (no medical history) and it's the only 'abnormality' in my normal, generally healthy, life.

Kidney stones are a well known side effect of ketogenic diets.