The ketogenic diet is based on the principle that by depleting the body of carbohydrates, which are its primary source of energy, you can force the body to burn fat for fuel, thereby maximizing weight loss. When you consume foods that contain carbohydrates, the body converts those carbohydrates into glucose, or blood sugar, which it then uses for energy. (1)
On the ketogenic diet, carbohydrates are restricted and so cannot provide for all the metabolic needs of the body. Instead, fatty acids are used as the major source of fuel. These are used through fatty-acid oxidation in the cell's mitochondria (the energy-producing parts of the cell). Humans can convert some amino acids into glucose by a process called gluconeogenesis, but cannot do this by using fatty acids.[56] Since amino acids are needed to make proteins, which are essential for growth and repair of body tissues, these cannot be used only to produce glucose. This could pose a problem for the brain, since it is normally fuelled solely by glucose, and most fatty acids do not cross the blood–brain barrier. However, the liver can use long-chain fatty acids to synthesise the three ketone bodies β-hydroxybutyrate, acetoacetate and acetone. These ketone bodies enter the brain and partially substitute for blood glucose as a source of energy.[55]
Because some cancer cells are inefficient in processing ketone bodies for energy, the ketogenic diet has also been suggested as a treatment for cancer.[58][59] A 2018 review looked at the evidence from preclinical and clinical studies of ketogenic diets in cancer therapy. The clinical studies in humans are typically very small, with some providing weak evidence for anti-tumour effect, particularly for glioblastoma, but in other cancers and studies, no anti-tumour effect was seen. Taken together, results from preclinical studies, albeit sometimes contradictory, tend to support an anti-tumor effect rather than a pro-tumor effect of the KD for most solid cancers.[60]
Children who discontinue the diet after achieving seizure freedom have about a 20% risk of seizures returning. The length of time until recurrence is highly variable but averages two years. This risk of recurrence compares with 10% for resective surgery (where part of the brain is removed) and 30–50% for anticonvulsant therapy. Of those that have a recurrence, just over half can regain freedom from seizures either with anticonvulsants or by returning to the ketogenic diet. Recurrence is more likely if, despite seizure freedom, an electroencephalogram (EEG) shows epileptiform spikes, which indicate epileptic activity in the brain but are below the level that will cause a seizure. Recurrence is also likely if an MRI scan shows focal abnormalities (for example, as in children with tuberous sclerosis). Such children may remain on the diet longer than average, and it has been suggested that children with tuberous sclerosis who achieve seizure freedom could remain on the ketogenic diet indefinitely.[45]

The ketogenic diet—also known as "keto"—has become the latest big thing in weight-loss plans, touted recently by celebs like Jenna Jameson, Mama June, and Halle Berry. The diet involves cutting way back on carbohydrates, to 50 grams a day or less, to help the body achieve a state of ketosis, in which it has to burn fat (rather than sugar) for energy.

As for how it feels to follow the diet, St. Pierre says it will vary from person to person; as with most diet-related things, whether or not a way of eating works is in the eye of the beholder. He’s seen some people feel fine, but that “some clients have found it causes brain fog and lethargy, decreases their performance, disrupts their regular bowel movements, and makes them feel generally crappy,” he says. Some keto adherents also report having pretty atrocious breath, which might be caused by the presence of acetone, a ketone and byproduct of fat metabolism, in exhaled breath.

The ketogenic diet is not a benign, holistic or natural treatment for epilepsy; as with any serious medical therapy, there may be complications.[27] These are generally less severe and less frequent than with anticonvulsant medication or surgery.[27] Common but easily treatable short-term side effects include constipation, low-grade acidosis and hypoglycaemia if there is an initial fast. Raised levels of lipids in the blood affect up to 60% of children[37] and cholesterol levels may increase by around 30%.[27] This can be treated by changes to the fat content of the diet, such as from saturated fats towards polyunsaturated fats, and, if persistent, by lowering the ketogenic ratio.[37] Supplements are necessary to counter the dietary deficiency of many micronutrients.[3]


Don’t stick to chicken and steak just because you’re comfortable cooking them. Make dinner time the place where you can try new meats and recipes that increase your keto recipe resources. “At lunch and dinner, you can be creative and experiment,” Weaver says. “Just focus on cooking meat—pork, chicken, lamb, beef, or seafood. Meat is rich in iron and fish contains omega-3 fatty acids and vitamin D. Use only organic oils, such as avocado oil, coconut oil, and olive oil.”

I have been on a low carb keto diet for more than a year. As T2DM my A1C dropped from 9% to 5.4% & I discontinued meds. All my lipids improved even with ample healthy saturated fat. More than a year now so I wonder why this would be a short term improvement when its obvious that I will not go back to a high A1C and taking 3 diabetes medications including sulphonylureas. It is clear from this article that you lack the necessary experience that would be gained from wholeheartedly trying the diet or monitoring patients doing it properly like me. I would be probably be facing my first amputation if I believed the negativity in your article. So for people with diabetes who may be dissuaded by your article. Ignore it and take back your health by restricting carbs (<25 g a day) or as low as you reasonably can below 130g while being satisfied that you are getting adequate nutrition.
A keto diet has shown to improve triglyceride levels and cholesterol levels most associated with arterial buildup. More specifically low-carb, high-fat diets show a dramatic increase in HDL and decrease in LDL particle concentration compared to low-fat diets.3A study in the long-term effects of a ketogenic diet shows a significant reduction in cholesterol levels, body weight, and blood glucose. Read more on keto and cholesterol >
There are so many tricks, shortcuts, and gimmicks out there on achieving optimal ketosis – I’d suggest you don’t bother with any of that. Optimal ketosis can be accomplished through dietary nutrition alone (aka just eating food). You shouldn’t need a magic pill to do it. Just stay strict, remain vigilant, and be focused on recording what you eat (to make sure your carb and protein intake are correct).
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I’ve been sugar free for 14 years, but sugar free doesn’t necessarily mean low carb or keto. For me back then it meant no white sugar, white flour or anything white or refined. I still enjoyed sweet potatoes and even honey. As the years went on I discovered even natural sugars caused me to continue to crave and I eventually went low carb back in 2013. I started my blog in 2011 so prior to 2013, some of the recipes are not low carb just sugar free. Here’s a post I wrote about the Differences between a Sugar Free and a Low Carb Diet.
Con: Results can vary depending on how much fluid you drink. By drinking more water, you dilute the concentration of ketones in the urine and thus a lower level of ketones will be detected on the strips. The strips don’t show a precise ketone level. Finally, and most importantly, as you become increasingly keto-adapted and your body reabsorbs ketones from the urine, urine strips may become unreliable, even if you’re in ketosis.

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There are theoretically no restrictions on where the ketogenic diet might be used, and it can cost less than modern anticonvulsants. However, fasting and dietary changes are affected by religious and cultural issues. A culture where food is often prepared by grandparents or hired help means more people must be educated about the diet. When families dine together, sharing the same meal, it can be difficult to separate the child's meal. In many countries, food labelling is not mandatory so calculating the proportions of fat, protein and carbohydrate is difficult. In some countries, it may be hard to find sugar-free forms of medicines and supplements, to purchase an accurate electronic scale, or to afford MCT oils.[53]
Diarrhea can also be due to a lack of fiber in the diet, says Kizer, which can happen when someone cuts way back on carbs (like whole-grain bread and pasta) and doesn’t supplement with other fiber-rich foods, like vegetables. It can also be caused by an intolerance to dairy or artificial sweeteners—things you might be eating more of since switching to a high-fat, low-carb lifestyle.
The keto diet cuts out so many healthful foods and is so difficult to follow, even the most outspoken proponents of the plan say it should be followed only temporarily. The issue is that when people go off the plan, they gain the weight back—and then some, Macri says. Some people find success, though: Read the secrets of people who’ve maintained their weight loss.
I have great respect for Harvard Medical School. I notice that they support their readers posting comments and I am most appreciative of the article and all the many thoughtful comments by the readers. The readers seem to have the most expertise here and I hope that the doctor who wrote the article will think long and hard about the comments by readers. After 35 years of clinical practice in mental health, I notice that all issues of emotion involve medical issues, nutrition, and the gut bacteria. I would say that these issues and all of the executive brain functions seem to improve with ketogenic principles. For those that apply it in a flexible and smart manner, it appears to improve every area of their lives. I strongly encourage the author of the article to take one class via The Institute for Functional Medicine. If he is open to more learning he can take more classes and get certified. I’m sure a fine doctor, he will be an even better doctor and personally healthier, if he gets more training. Are we all open to new learning(especially us healthcare providers)?
But to summarize, I started keto as a pretty vocal anti-keto'er. After a bunch of research on infertility and how the keto diet may help with it, I just had to give it a try. No baby yet, but wow, the changes are remarkable. Currently I'm doing about 1/2 lazy keto and 1/2 strict keto, due to how much I travel for work. 1-2 days/week I walk an hour. That's it.
One of the most common side effects of starting the ketogenic diet is the “keto flu.” This term describes the often unpleasant, fatigue-inducing symptoms that occur as the body adjusts from a high-carbohydrate to a low-carbohydrate diet. During the keto flu, the body’s stored glucose begins depleting, and the body starts adapting to producing and utilizing ketones as energy. (2)
What's more, it's especially important to make sure your diet is well-planned when you're eating keto-style, because the foods you can choose from are limited. In addition to checking in with a dietitian if you're able, Stefanski recommends that you "talk to your doctor and make sure she or he is aware that you'll be starting a diet that completely changes how your body metabolizes energy." You might also want to check your most recent bloodwork levels for things such as cholesterol, vitamin D, and other indicators of health because these can change while on keto. That's because for some people, a prolonged keto diet can result in certain nutritional deficiencies or even high cholesterol. But most experts will tell you that the ketogenic diet is not a permanent lifestyle change (as could be the case for something like the 80/20 approach to eating or a Mediterranean eating style).
Achieving optimal ketosis hinges on finding the right balance of macronutrients (or “macros” in keto-speak); these are the elements in your diet that account for the majority of your calories, a.k.a. energy—namely, fat, protein, and carbohydrates. By the way, it’s often “net grams” of carbohydrates that are counted toward your daily intake; “net” deducts the amount of fiber in a food from its carbohydrate total.
Dr. Campos, it is so discouraging to see that you disparage the ketogenic diet based on your assumption that it is very heavy in poor quality processed meats. No diet that relies on processed foods can be viewed as “healthy”. Become better informed by getting up to speed with what Jeff Volek, RD, PhD, calls a “well-formulated ketogenic diet.” Also, learn more about the potential of the diet to slow cancer progression (my specialty). You owe it to your patients who are depending on you for advice. Present them with facts, not opinions.
First real post! Bear with me lol. I’m just hoping I did it right. I started keto in early September after losing about 50 pounds counting calories. I was happy with the loss but it took so long and I couldn’t stick with it. I felt yucky most days and I was always hungry. Then a girl I worked with told me about keto. I started researching it and found reddit and y’all. You guys are by far the most supportive, enthusiastic, and kindest group on reddit! I come here every morning and every evening to check out your pics, progress, and tips. Everyone is so inspiring. Your enthusiasm is contagious. I do lazy keto. Very. I don’t really count anything. I just eat keto foods and I’m full all day. I still have a long way to go. But I’m sure this time, it’s last time I’m losing weight. Rock on fellow keto peeps! I’m thankful for all of you😀

The main objective of the ketogenic diet is to get the body to start relying primarily on fat for energy. In general, our bodies are predominantly fueled by glucose (also known as blood sugar), which we get from carb-rich foods (bread, cereal, pasta, rice, etc.). The digestive tract breaks these foods down into glucose so it can be converted into adenosine triphosphate (ATP), which is the chemical our bodies can use for energy. But when the body is deprived of carby delights, it finds other ways to make energy, and one way is a process called ketogenesis. During ketogenesis, the body turns to fat for energy; the liver breaks it down into ketones, making it a usable energy source, Amy M. Goss, Ph.D., assistant professor at the University of Alabama at Birmingham’s Nutrition Obesity Research Center, explains to SELF via email.


To get the most benefit from the Keto diet, you should stay physically active. You might need to take it easier during the early ketosis period, especially if you feel fatigued or lightheaded. Walking, running, doing aerobics, weightlifting, training with kettlebells or whatever workout you prefer will boost your energy further. You can find books and online resources on how to adapt Keto meals or snacks for athletic training.
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