Is it unhealthy to be in ketosis for more than 6 months on a low carb diet? I would like to be in ketosis for a year if healthy.


Long-term ketogenic diet can have various side effects.

Safety and tolerability of the ketogenic diet used for the treatment of refractory childhood epilepsy: a systematic review of published prospective studies (PubMed, 2017):

The most common adverse effects included gastrointestinal disturbances (40.6%), hyperlipidemia (12.8%), hyperuricemia (4.4%), lethargy (4.1%), infectious diseases (3.8%) and hypoproteinemia (3.8%).

Dietary Therapies For Epilepsy (BioMed Journal, 2013):

Side effects include constipation, dyslipidemia, growth slowing, acidosis, and kidney stones.

Ketogenic diets and physical performance (PubMed, 2004):

Impaired physical performance is a common but not obligate result of a low carbohydrate diet.

Ketogenic diet in endocrine disorders: Current perspectives (PubMed, 2017):

The moderate adverse effects comprised of...mineral deficiencies...

Ketovale mentions many side effects from a mixture of anecdotal and study reports: the side effects mentioned above plus keto flu (headache, weakness, brain fog, increased hunger and fatigue), acetone-like breath, muscle cramps, insomnia, reduced bone mineral density, keto rash...

According to 2 cohort studies following 3,966 adults for 20-26 years: (PubMed, 2010)

A low-carbohydrate diet based on animal sources was associated with higher all-cause mortality in both men and women, whereas a vegetable-based low-carbohydrate diet was associated with lower all-cause and cardiovascular disease mortality rates.

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    Plus we don't have a lot of data on long-term safety (health impact) of ketogenic diets, especially the extended high fat intake (most especially the large quantities of animal fats) – DoctorWhom Nov 17 '18 at 11:46

You might be interested in this study: Long-term effects of a ketogenic diet in obese patients.

Specifically, for 83 obese study participants on a ketogenic (<30g carb/day) diet for 24 weeks:

The weight and body mass index of the patients decreased significantly (P<0.0001). The level of total cholesterol decreased from week 1 to week 24. HDL cholesterol levels significantly increased, whereas LDL cholesterol levels significantly decreased after treatment. The level of triglycerides decreased significantly following 24 weeks of treatment. The level of blood glucose significantly decreased. The changes in the level of urea and creatinine were not statistically significant.

All of these changes (weight and BMI decreased, total cholesterol decreased, LDL decreased, triglycerides decreased, HDL increased, blood glucose decreased) are normally considered to be indications of improved health.

  • This is a single and relatively small and short study. You can lose weight on any hypo-caloric diet and all the mentioned metabolic benefits could be simply a result of weight loss, not a ketogenic diet itself. You can read in this review that the metabolic complications can be simply due to obesity: "metabolic complications of obesity, such as type 2 diabetes, metabolic syndrome, impaired glucose tolerance, insulin resistance, hyperglycemia, and inflammation..." – Jan Nov 22 '18 at 10:13
  • The conclusion of this study review is that "ketogenic diets may be associated with some improvements in some cardiovascular risk factors, such as obesity, type 2 diabetes and HDL cholesterol levels, but these effects are usually limited in time." – Jan Nov 22 '18 at 10:36
  • The effects may be more related to the weight loss than the diet, as well - it is impossible to tell from this study. – DoctorWhom Nov 22 '18 at 19:38

Ketosis is not a healthy state for your body, a low carb diet by itself isn't healthy either as Dr. Klaper explains here. While you may not notice serious health problems after a year in ketosis, a great deal of damage will be done to your body.

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    Could you expand this answer? We look for an explanation as to why and less for argument from authority in videos but from reliable references. – LаngLаngС Nov 16 '18 at 19:29
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    I've read a good deal of Greger's work and have talked with him; he has historically been very evidence-based, so it shouldn't be too difficult to find some of his references he bases it on. I am a strong proponent of whole foods, plant-based diets, including in my own health, in part because of Greger. If you know where he's gathered references for evidence about ketogenic diets, I'd love to check it out – DoctorWhom Nov 16 '18 at 23:56
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    I'll check out the sources and update the answer. – Count Iblis Nov 17 '18 at 1:44

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