Disclaimer: I'm an obsessive researcher, not a doctor, and the following is intended as advice. I'm not diagnosing or treating any disease, since the AMA has a government-granted monopoly on that.

Don't care about the details? Skip right to the take-home message

Dr. Atkins has claimed many times that the "benign dietary ketosis" (BDK) which a low-carb diet induces is different from diabetic ketoacidosis (DKA), and the former has none of the ill effects of the latter (ie this interview). In DKA, which happens to diabetics who eat too much sugar or have too little insulin, the bloodstream is full of sugar ("hyperglycemia"), but there is no insulin available. So the body can neither remove sugar from the blood nor utilize it for energy. Hyperglycemia is dangerous, and high-levels are fatal (more info). DKA also results in high levels of ketones, because without insulin, the body must burn fats for energy.

Atkins appears to have invented the term BDK to denote a state of mild ketosis without hyperglycemia. This commonly results from eating a low-carb diet, or fasting, so the body has to burn stored fat. As a note, this sort of ketosis is what causes morning breath, because our body often runs out of carbs during the night. So the main difference between BDK and DKA is whether there are high (or extremely high) blood sugar levels along with the ketosis.

Its true that extreme hyperglycemia is quite bad, and believed to be the cause of the most acute symptoms of DKA. However, that does not mean that all the effects of DKA are due to hyperglycemia and none to ketosis. It does not mean that ketosis has no long-term chronic effects. Yet Atkins claims, without any proof that I've been able to find, that BDK is completely healthy, totally different than DKA, and has none of its ill-effects.

Ketones are acidic and mildly poisonous. Two major ketones are acetoacetic acid and beta-hydroxybutyric acid, which are strong organic acids. Excreting them causes the loss of sodium and potassium. The way acetoacetic acid is broken down (spontaneous decarboxylation) produces acetone - not a nice thing to have in your bloodstream. Acetone accumulates in plasma and is slowly disposed of by respiration (reference).

This doesn't mean that ketosis is terrible for you, just that we shouldn't assume its totally safe without evidence. Luckily, the medical literature contains several references on "ketogenic" diets - diets which are low in carbs and induce ketosis. While most of us are interested in low-carb diets for cardio health or weight loss, these diets are studied for a different reason - they help prevent seizures (study showing effectiveness) . This dietary approach to controlling seizures is used when there are reasons not to use drugs, such as children who are epileptic. By looking at this literaure, we can obtain a more balanced viewpoint than that of Dr. Atkins. Brief summaries of the articles I found are below, along with links to their abstracts.

Good things about ketosis:

• The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. This study found that cyclists who switched to a ketogenic diet had no reduction in their aerobic exercise endurance, although their body switched from using sugar to using fat for energy.

• The human metabolic response to chronic ketosis without caloric restriction: physical and biochemical adaptation. "the ketotic state induced by the EKD was well tolerated in lean subjects; nitrogen balance was regained after brief adaptation, serum lipids were not pathologically elevated, and blood glucose oxidation at rest was measurably reduced while the subjects remained euglycemic".

• Higher ketogenic diet ratios confer protection from seizures without neurotoxicity.

• Diet-induced ketosis does not cause cerebral acidosis.

• The ketogenic diet may have mood-stabilizing properties (for bipolar disorder).

• beta-hydroxybutyric acid reduces seizure likelihood.

• A rat study found no neurotoxicity.

• This study seems to indicates that mild chronic ketosis is usually OK, but can cause problems and should be monitored carefully.

Bad things about ketosis:

• ketosis increases likelihood of bruising.

• fasting decreases immune function (this study suggests that the first study applies to atkins-induced ketosis).

• ketosis does bad things to the kidneys.

• Some evidence that ketosis in diabetics is identical to ketosis in normal individuals (although perhaps more extreme).

• Low-carb is better than no-carb ("Although some workers use VLCD consisting only of protein, the author prefers those also containing carbohydrate because they prevent excessive ketosis, hyperuricemia, diuresis, electrolyte loss, re-feeding oedema, and may improve muscular endurance").

• ketosis causes vitamin D deficiency and decreased bone mass.

From this evidence we can see that Atkins portrayal of "BDK" as totally harmless is a distortion of the truth. Because ketosis usually occurs in the context of DKA, he can blame all the ill effects on the hyperglycemia & extremeness of the ketosis. These are likely responsible for the acute effects, but ketosis is not harmless. It is unclear exactly what the health risks of long-term mild chronic ketosis is, but we can see that there are some, although they appear fairly mild. BDK is thus a loaded term, and in my opinion this reflects poorly on Dr. Atkins and his reliability.

However, please don't let the takeaway lesson be that Atkins is a nut or that eating low-carbs is bad for you. I believe firmly in milder versions of much of what he preaches (having researched the subject a fair amount). Instead, let the take home lesson be:

By letting your body get some energy from burning low-glycemic index sugars, you should reduce or avoid the mild dangers of ketosis while avoiding the many serious, long-term dangers of sugar, and in particular of elevated blood sugar levels. Epileptics on ketogenic diets generally don't have serious problems, and the diets are considered fairly safe, if not completely without side effect. It is likely that for many, any ill effects of mild BDK are outweighed by the advantages of a low-carbohydrate diet. There is plenty of strong evidence for the advantages of low-carb and low-glycemic index diets. Personally, I eat a low-carb diet w/ lots of protein, fat, and veggies, and enough low-gi carbs to keep my ketones low. You are welcome to read the abstracts above and judge for yourself.

The South Beach Diet, pictured at the right, is one of the closest to ideal that I know, as unlike Atkins it stresses the difference between types of fat and types of carbs.

Here are some other views I found on the Atkins diet. While I think the negative ones are exaggerated and not good representations of the truth, they are included for completeness.

GetZoned Australia: "It's bad for your kidneys" is the common criticism of this diet. The reasons given are invariably one or more of: too much protein causes kidney disease, too much protein causes ketosis, and too many ketone bodies cause kidney disease. Part of the problem stems from the failure to distinguish between benign dietary ketosis, the harmless form of ketosis that the Atkins' diet strives for, and ketoacidosis, a dangerous form that type I diabetics can develop that is not related to diet. As for the high level of protein, yes it does make your kidneys work harder, Dr Atkins even warns people with kidney disease against his diet, but it doesn't cause kidney disease. Healthy kidneys are perfectly capable of coping with the added load of protein, and ketone bodies for that matter. [link]

Contrary views:

Hazards of a Low Carbohydrate Diet: "diets high in protein, especially animal protein, are very hard on kidneys, causing them to work too hard to remove the waste products of protein metabolism." Further information can be found here: [link]

"Cox and Knutsen also are skeptical about the metabolic mechanism, ketosis, that initiates the rapid weight loss. Ketosis results from the incomplete metabolism of fatty acids. It comes on when the body is deprived of carbohydrates, its preferred fuel source, and turns to its own fat and the fat in food for fuel. The body assembles the fatty-acid fragments into substances called ketones. These are poisonous to the system, and the body flushes them out in the urine with water, according to the Tufts University Health and Nutrition Letter. So the initial rapid weight loss on the Atkins diet is mostly water.

"The body must also break down its own muscle tissue to provide the brain and red blood cells with glucose, a required nutrient," Cox says. "Muscle tissue holds water, and when lost, results in a significant amount of weight loss."

Getting the body into a state of ketosis is the induction or "crash" phase of the Atkins diet, accomplished by cutting daily carbohydrate intake to 40 grams, down from the 300 grams the average person consumes. In this state, which Atkins calls "benign dietary ketosis," the appetite is suppressed. Cox and Knutsen doubt that any kind of ketosis is benign. Knutsen says it's basically metabolic starvation. And Cox says that according to the American Dietetics Association, ketosis is dangerous for people with kidney problems or gout, and it's not good for pregnant women or nursing mothers." [link]

"Dietary protein and weight reduction: a statement for healthcare professionals from the Nutrition Committee of the Council on Nutrition, Physical Activity, and Metabolism of the American Heart Association"

Note: This is one of the most popular pages on my website, almost all from search-engine hits. Clearly a lot of people are interested in learning about how ketosis from a low-carb diet affects health. I've re-written this article and it should now be a lot easier to read and understand (5/03).

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