Note the emphasis on ketosis as a temporary adaptive state. Our ancestors could not be in fasting-induced ketosis permanently because they would eventually exhaust their fat reserves (which were presumably far more limited than ours, owing to the simple fact that they ate less and moved more than we do). They would then progress from fasting to starving, and subsequently die.

The ketogenic diet is a mainstream dietary therapy that was developed to reproduce the success and remove the limitations of the non-mainstream use of fasting to treat epilepsy.[Note 2] Although popular in the 1920s and '30s, it was largely abandoned in favour of new anticonvulsant drugs.[1] Most individuals with epilepsy can successfully control their seizures with medication. However, 20–30% fail to achieve such control despite trying a number of different drugs.[9] For this group, and for children in particular, the diet has once again found a role in epilepsy management.[1][10]
As discussed in the first article of this series, ketosis is a metabolic state in which the brain switches to using ketone bodies – derived from the breakdown of fat – as its primary energy source, instead of glucose. This way body protein, which would otherwise be broken down and converted into glucose through the process of gluconeogenesis, are spared.
If you’ve decided to move forward in trying the keto diet, you will want to stick to the parameters of the eating plan. Roughly 60 to 80 percent of your calories will come from fats. That means you’ll eat meats, fats, and oils, and a very limited amount of nonstarchy vegetables, she says. (This is different from a traditional low-carb diet, as even fewer carbs are allowed on the keto diet.)
I just have to tell you, just to remind you, I am a type 1 diabetic and have been for 34 years. My kidney function has been going down gradually for several years including 4 points from June of this year to August. My GFR score was 42 in August, which I was told was stage 3 kidney failure. As of October 24 — I just got the results today — but as of October 24 my GFR score was 57 — 60 is considered normal. 
Our human ancestors did not consume high-fat, low-carbohydrate diets and therefore would not have been in diet-induced ketosis. Even the most successful early hunters could not possibly have consumed enough fat to enter ketosis since african wildlife such as wildebeests, warthogs and impalas all have low body fat – well under 10%, and as low as 0.3%[6] in the dry season.
Because the ketogenic diet alters the body's metabolism, it is a first-line therapy in children with certain congenital metabolic diseases such as pyruvate dehydrogenase (E1) deficiency and glucose transporter 1 deficiency syndrome,[35] which prevent the body from using carbohydrates as fuel, leading to a dependency on ketone bodies. The ketogenic diet is beneficial in treating the seizures and some other symptoms in these diseases and is an absolute indication.[36] However, it is absolutely contraindicated in the treatment of other diseases such as pyruvate carboxylase deficiency, porphyria, and other rare genetic disorders of fat metabolism.[9] Persons with a disorder of fatty acid oxidation are unable to metabolise fatty acids, which replace carbohydrates as the major energy source on the diet. On the ketogenic diet, their bodies would consume their own protein stores for fuel, leading to ketoacidosis, and eventually coma and death.[37]
Look, the good doctor is right – he only forgot to stress “portion control” which is why many fanatical dieters are so kee-jerk reactive to any discussion – odds are you over ate like a hog before your keto diet, and are weak and insecure in your diet plans. Eat EVERYTHING in small amounts, and you will live long and prosper. The only thing to avoid are processed foods. Cook your meals from scratch using quality ingredients.

Furthermore, humans develop a condition dubbed ‘rabbit starvation’[7] when they eat a diet that is low in fat and carbohydrates, and high in protein (> 35% of total daily energy intake). This is due to the inability of the human liver to sufficiently upregulate urea synthesis to meet excessive loads of protein. Consequently, hyperaminoacidemia, hyperammonemia, hyperinsulinemia, nausea, diarrhea, and even death can ensue within 2 to 3 weeks. These effects were recognized historically through the excess consumption of lean wild meat by early American explorers.[8]

First, that study, which was reported upon widely, was on mice. Mice are not like humans in the way they fatten or contract metabolic diseases. Journalists/media should stop reporting on mice stories as if they were applicable to humans, especially when there is such a large body of clinical trial data on humans. Let’s be clear: rigorous clinical trial data on humans trumps any data on mice. Every time. And what does the rigorous data on humans say?


Bread probably isn’t the first thing that comes to mind when you think about the ketogenic diet because it’s generally full of carbs. But, if you replace your store-bought bread with a homemade keto bread recipe, it can fit seamlessly into your keto low-carb, high-fat diet. How does bread even become keto-friendly? With almond flour, a lot of eggs, cream of tartar, butter, baking soda and apple cider vinegar.


A ketogenic diet could be an interesting alternative to treat certain conditions, and may accelerate weight loss. But it is hard to follow and it can be heavy on red meat and other fatty, processed, and salty foods that are notoriously unhealthy. We also do not know much about its long-term effects, probably because it’s so hard to stick with that people can’t eat this way for a long time. It is also important to remember that “yo-yo diets” that lead to rapid weight loss fluctuation are associated with increased mortality. Instead of engaging in the next popular diet that would last only a few weeks to months (for most people that includes a ketogenic diet), try to embrace change that is sustainable over the long term. A balanced, unprocessed diet, rich in very colorful fruits and vegetables, lean meats, fish, whole grains, nuts, seeds, olive oil, and lots of water seems to have the best evidence for a long, healthier, vibrant life.
A survey of 1,580 low-carb consumers published in late 2017 by the Journal of Insulin Resistance45 found that while more than 11% of respondents reported using sleep-aids before beginning their low-carb diet, less than 5% reported using them after their diet. Moreover, nearly seven in 10 reported improved quality of sleep after dieting while only 3.4% said their sleep quality had worsened.
There is nothing inherently difficult about following a ketogenic diet. We have many patients who do this very easily over many years. The metabolic benefits significantly outway any perceived challenges from limiting particular food types. Uptake would be far more widespread if nutrition professionals left their predujical opinions of SFA’s behind. Finally, given the expertise in Ketogenic Diets at Harvard, Dr David Ludwig, for one springs to mind, I am surprised the author did not avail themselves of the local expertise.

Full disclosure: I have followed a low-carb diet for nearly a decade and find no problem adhering to it. I’ve lost weight and all my cardiovascular biomarkers have improved. Moreover, I’ve studied the science and history behind low-carbohydrate diets, so beyond my personal experience, I bring an evidence-based perspective. (Previously, for 25+ years, I adhered faithfully to a “mostly plants” regimen of fruits, veggies, and whole grains, including my own homemade 7-grain bread, while exercising religiously. Yet during that time my blood lipids were unhealthy, and I never could shake an extra 10-20 pounds.)


The ketogenic diet reduces seizure frequency by more than 50% in half of the patients who try it and by more than 90% in a third of patients.[18] Three-quarters of children who respond do so within two weeks, though experts recommend a trial of at least three months before assuming it has been ineffective.[9] Children with refractory epilepsy are more likely to benefit from the ketogenic diet than from trying another anticonvulsant drug.[1] Some evidence indicates that adolescents and adults may also benefit from the diet.[9]
Even when exercising at a submaximal level (for example, biking at a moderate speed), heart rate and adrenaline levels rise more when people are eating a high-fat, low-carbohydrate diet[4] vs. a high-carbohydrate, low-fat diet. This results in those on the high fat diet perceiving that they are working harder to achieve the same pace as the high-carbers, and they have much more difficulty speeding up their pace in sprints or climbs.
Infants and patients fed via a gastrostomy tube can also be given a ketogenic diet. Parents make up a prescribed powdered formula, such as KetoCal, into a liquid feed.[19] Gastrostomy feeding avoids any issues with palatability, and bottle-fed infants readily accept the ketogenic formula.[31] Some studies have found this liquid feed to be more efficacious and associated with lower total cholesterol than a solid ketogenic diet.[18] KetoCal is a nutritionally complete food containing milk protein and is supplemented with amino acids, fat, carbohydrate, vitamins, minerals and trace elements. It is used to administer the 4:1 ratio classic ketogenic diet in children over one year. The formula is available in both 3:1 and 4:1 ratios, either unflavoured or in an artificially sweetened vanilla flavour and is suitable for tube or oral feeding.[51] Other formula products include KetoVolve[52] and Ketonia.[53] Alternatively, a liquid ketogenic diet may be produced by combining Ross Carbohydrate Free soy formula with Microlipid and Polycose.[53]
^ Freeman JM, Vining EP, Pillas DJ, Pyzik PL, Casey JC, Kelly LM. The efficacy of the ketogenic diet—1998: a prospective evaluation of intervention in 150 children. Pediatrics. 1998 Dec;102(6):1358–63. doi:10.1542/peds.102.6.1358. PMID 9832569. https://web.archive.org/web/20040629224858/http://www.hopkinsmedicine.org/press/1998/DECEMBER/981207.HTM Lay summary]—JHMI Office of Communications and Public Affairs. Updated 7 December 1998. Cited 6 March 2008.
Because people with type 2 diabetes are at an increased risk for cardiovascular disease, there’s a specific concern that the saturated fat in the diet may drive up LDL, or “bad,” cholesterol levels, and further increase the odds of heart problems. If you have type 2 diabetes, talk to your doctor before attempting a ketogenic diet. They may recommend a different weight-loss diet for you, like a reduced-calorie diet, to manage diabetes. Those with epilepsy should also consult their doctor before using this as part of their treatment plan.
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