In a study done with 8 groups of obese individuals, researchers found that different amounts of dietary carbohydrates affect T3 and reverse T3 levels in different ways. T3 levels only decreased when the subjects consumed 120 grams of carbohydrates per day or less (regardless of how calorie-restricted they were). Reverse T3 levels, on the other hand, began to increase when carbohydrate intake was between 40 and 50 grams of carbohydrates per day.
Another mineral you may want to supplement is potassium. While there is no concrete evidence that a dramatic potassium loss occurs on a low-carb regimen, Sondike says to ensure against problems he recommends patients use Morton's Light Salt -- a potassium chloride product that he says can add back any of this important mineral that's lost. Eating a few almonds is also a good way to supplement this mineral without adding carbs to your diet.
Normal dietary fat contains mostly long-chain triglycerides (LCTs). Medium-chain triglycerides (MCTs) are more ketogenic than LCTs because they generate more ketones per unit of energy when metabolised. Their use allows for a diet with a lower proportion of fat and a greater proportion of protein and carbohydrate,[18] leading to more food choices and larger portion sizes.[4] The original MCT diet developed by Peter Huttenlocher in the 1970s derived 60% of its calories from MCT oil.[15] Consuming that quantity of MCT oil caused abdominal cramps, diarrhea, and vomiting in some children. A figure of 45% is regarded as a balance between achieving good ketosis and minimising gastrointestinal complaints. The classical and modified MCT ketogenic diets are equally effective and differences in tolerability are not statistically significant.[9] The MCT diet is less popular in the United States; MCT oil is more expensive than other dietary fats and is not covered by insurance companies.[18]
Eating slightly more carbs may potentially slow down weight loss and mute rapid, dramatic health improvements, but it can still lead to better health, especially if you are cutting out sugar and processed foods. And keto flu will no longer be an issue. Once you’ve adapted to low-carb eating, feel free to try eating less than 20 grams of carbs again to see whether your body prefers this or slightly higher carb intake.
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the WebMD Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
For patients who benefit, half achieve a seizure reduction within five days (if the diet starts with an initial fast of one to two days), three-quarters achieve a reduction within two weeks, and 90% achieve a reduction within 23 days. If the diet does not begin with a fast, the time for half of the patients to achieve an improvement is longer (two weeks), but the long-term seizure reduction rates are unaffected.[44] Parents are encouraged to persist with the diet for at least three months before any final consideration is made regarding efficacy.[9]
However, there is one caveat with eating more fat (and it is not heart disease). Most fats aren’t readily used as fuel, especially during the first few days of carbohydrate restriction. In fact, animal fats from meat and dairy have to go all the way through your lymphatic system to your heart, muscle cells, and fat cells before they reach the liver.
As for if you’re dealing with health issues, you really have to defer to your doctor. For instance, if you have kidney disease, you also want to talk to your doctor about appropriate protein intake. If you have heart disease, you can still go low carb, but you may be better off opting for monounsaturated fats (avocados, nuts, and olive oil) over saturated fats (butter and red meat). Everyone’s cholesterol levels respond differently on a low-carb diet, so if yours are going up, switch to unsaturated sources of fats, Spritzler recommends. “In general, this is a diet most people can do. If you have a chronic condition, work with a doctor who understands low-carbohydrate diets to monitor you,” she adds.
Not everyone should opt for a low-carb diet. If you’re pregnant, it’s possible to be on a lower-carb diet (and may even be indicated if you are told you have gestational diabetes), but talk to your doctor to find out what’s right for you and to ensure that you’re covering any potential nutrient gaps. “Many women who are pregnant find that the thought of eating protein and fat makes them sick,” says Spritzler. This can be especially common in the first trimester. “They naturally want more carbs. You should always listen to your body,” she says.
You can see the results, too. In January 2015, the Journal of Nutrition conducted two studies comparing lower-carb and low-fat diets, finding that of the two approaches, going lower carb helped people shave off more visceral fat, a type of belly fat that hugs organs and is linked to disease. (3) A meta-analysis published in June 2016 in Obesity Reviews also concluded that in obese people, a low-carb diet reduced fat over the course of a year (but not body weight), with the greatest benefits seen in a very-low-carb diet. (4)
Ketosis is pretty different from what your body is used to, and this onslaught of symptoms is its way of dealing with carb withdrawal—and adapting, explains Kristen Mancinelli, RD, author of The Ketogenic Diet. “It takes a while, usually a week or two, for the metabolic machinery to shift to fat-burning mode. And you’ll feel pretty crummy while the transition is happening,” she says.
Use our premium meal planner tool (free trial) to access tons of weekly meal plans, complete with shopping lists. You can adapt the diet plans to your liking, skipping any meal, choosing how many people you’re cooking for, and the shopping lists adapt. You can even start a new plan from scratch (of from pre-existing ones), tailor them completely and save them.
If you want to slam a protein shake post-workout, that's probably fine as long as you've got room for it in your macros. But shoot for one that is very low—like, zero—in carbohydrates. Pure isolates, such as Signature 100% Whey Isolate, are extremely low in carbohydrate. If you struggle to fit fat in during the day, toss a tablespoon of olive oil in with your shake. You won't taste it, and it gives a quick 13-14 grams of fat.
Implementing the diet can present difficulties for caregivers and the patient due to the time commitment involved in measuring and planning meals. Since any unplanned eating can potentially break the nutritional balance required, some people find the discipline needed to maintain the diet challenging and unpleasant. Some people terminate the diet or switch to a less demanding diet, like the modified Atkins diet or the low-glycaemic index treatment diet, because they find the difficulties too great.[42]
First reported in 2003, the idea of using a form of the Atkins diet to treat epilepsy came about after parents and patients discovered that the induction phase of the Atkins diet controlled seizures. The ketogenic diet team at Johns Hopkins Hospital modified the Atkins diet by removing the aim of achieving weight loss, extending the induction phase indefinitely, and specifically encouraging fat consumption. Compared with the ketogenic diet, the modified Atkins diet (MAD) places no limit on calories or protein, and the lower overall ketogenic ratio (about 1:1) does not need to be consistently maintained by all meals of the day. The MAD does not begin with a fast or with a stay in hospital and requires less dietitian support than the ketogenic diet. Carbohydrates are initially limited to 10 g per day in children or 20 g per day in adults, and are increased to 20–30 g per day after a month or so, depending on the effect on seizure control or tolerance of the restrictions. Like the ketogenic diet, the MAD requires vitamin and mineral supplements and children are carefully and periodically monitored at outpatient clinics.[48]
Because some cancer cells are inefficient in processing ketone bodies for energy, the ketogenic diet has also been suggested as a treatment for cancer.[59][60] 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.[61]
Low-carb diets may help prevent or improve serious health conditions, such as metabolic syndrome, diabetes, high blood pressure and cardiovascular disease. In fact, almost any diet that helps you shed excess weight can reduce or even reverse risk factors for cardiovascular disease and diabetes. Most weight-loss diets — not just low-carb diets — may improve blood cholesterol or blood sugar levels, at least temporarily.
But beyond that, experts aren't convinced that the keto diet has any other scientifically proven health benefits. In fact, it may have some distinct downsides. If you follow the keto diet incorrectly, for example (like by eating lots of saturated fats, versus healthy unsaturated fats), you're at risk of raising your cholesterol levels. “The best strategy to keep your heart healthy is to get as much fat as possible from unsaturated sources such as olive, avocado and canola oils, nuts, seeds, avocados, and olives," says Ansel. For some people, it's possible to actually improve cholesterol if the fats in their diet are from varied and healthy sources, says Harvey.
By default, your body burns glucose (carbs) as its primary energy source, but when you switch to an extremely low carb diet, your body will begin to burn fatty acids for energy instead. Fat is your body’s secondary or “backup” fuel source, which can only be tapped when there’s not enough glucose in your diet. When your body begins burning fat as fuel instead of carbs, you’ve entered the metabolic state known as ketosis (1).
This article was reviewed by Jes Harvey, RD. Harvey is a registered dietitian specializing in the ketogenic diet for children and adults. She is a certified specialist in Pediatric Nutrition and educates children with epilepsy on the ketogenic diet as an anti-seizure medication. Harvey also manages a private nutrition practice consulting adults on the ketogenic way of eating.
Physicians of ancient Greece treated diseases, including epilepsy, by altering their patients' diet. An early treatise in the Hippocratic Corpus, On the Sacred Disease, covers the disease; it dates from c. 400 BC. Its author argued against the prevailing view that epilepsy was supernatural in origin and cure, and proposed that dietary therapy had a rational and physical basis.[Note 3] In the same collection, the author of Epidemics describes the case of a man whose epilepsy is cured as quickly as it had appeared, through complete abstinence of food and drink.[Note 4] The royal physician Erasistratus declared, "One inclining to epilepsy should be made to fast without mercy and be put on short rations."[Note 5] Galen believed an "attenuating diet"[Note 6] might afford a cure in mild cases and be helpful in others.[11]

Ketosis is pretty different from what your body is used to, and this onslaught of symptoms is its way of dealing with carb withdrawal—and adapting, explains Kristen Mancinelli, RD, author of The Ketogenic Diet. “It takes a while, usually a week or two, for the metabolic machinery to shift to fat-burning mode. And you’ll feel pretty crummy while the transition is happening,” she says.


In Asia, the normal diet includes rice and noodles as the main energy source, making their elimination difficult. Therefore, the MCT-oil form of the diet, which allows more carbohydrate, has proved useful. In India, religious beliefs commonly affect the diet: some patients are vegetarians, will not eat root vegetables or avoid beef. The Indian ketogenic diet is started without a fast due to cultural opposition towards fasting in children. The low-fat, high-carbohydrate nature of the normal Indian and Asian diet means that their ketogenic diets typically have a lower ketogenic ratio (1:1) than in America and Europe. However, they appear to be just as effective.[54]

Ketosis is pretty different from what your body is used to, and this onslaught of symptoms is its way of dealing with carb withdrawal—and adapting, explains Kristen Mancinelli, RD, author of The Ketogenic Diet. “It takes a while, usually a week or two, for the metabolic machinery to shift to fat-burning mode. And you’ll feel pretty crummy while the transition is happening,” she says.
The ketone bodies are possibly anticonvulsant; in animal models, acetoacetate and acetone protect against seizures. The ketogenic diet results in adaptive changes to brain energy metabolism that increase the energy reserves; ketone bodies are a more efficient fuel than glucose, and the number of mitochondria is increased. This may help the neurons to remain stable in the face of increased energy demand during a seizure, and may confer a neuroprotective effect.[56]

Early studies reported high success rates; in one study in 1925, 60% of patients became seizure-free, and another 35% of patients had a 50% reduction in seizure frequency. These studies generally examined a cohort of patients recently treated by the physician (a retrospective study) and selected patients who had successfully maintained the dietary restrictions. However, these studies are difficult to compare to modern trials. One reason is that these older trials suffered from selection bias, as they excluded patients who were unable to start or maintain the diet and thereby selected from patients who would generate better results. In an attempt to control for this bias, modern study design prefers a prospective cohort (the patients in the study are chosen before therapy begins) in which the results are presented for all patients regardless of whether they started or completed the treatment (known as intent-to-treat analysis).[19]
You probably hear the most about low-carb eating for weight loss, but for some people, the approach could also help optimize their health, says Schmidt. “Research shows that women who are obese or have metabolic problems [may] do better hormonally on lower carbs,” says Schmidt, pointing out that other outcomes of the diet can include better sleep, mental clarity, and increased satiety. (1)
In Asia, the normal diet includes rice and noodles as the main energy source, making their elimination difficult. Therefore, the MCT-oil form of the diet, which allows more carbohydrate, has proved useful. In India, religious beliefs commonly affect the diet: some patients are vegetarians, will not eat root vegetables or avoid beef. The Indian ketogenic diet is started without a fast due to cultural opposition towards fasting in children. The low-fat, high-carbohydrate nature of the normal Indian and Asian diet means that their ketogenic diets typically have a lower ketogenic ratio (1:1) than in America and Europe. However, they appear to be just as effective.[54]
More good news: Snacks are totally allowed (and I'm not just talking about carrot sticks). There are plenty of packaged options out there designed for keto fans. FATBAR is one of them. These snack bars have 200 calories, 16 grams of fat, and four grams of net carbs. They're also plant-based and are made with almond or cashew butter, cocoa butter, coconut, pea protein, sunflower seeds, and chia seeds.
Anticonvulsants suppress epileptic seizures, but they neither cure nor prevent the development of seizure susceptibility. The development of epilepsy (epileptogenesis) is a process that is poorly understood. A few anticonvulsants (valproate, levetiracetam and benzodiazepines) have shown antiepileptogenic properties in animal models of epileptogenesis. However, no anticonvulsant has ever achieved this in a clinical trial in humans. The ketogenic diet has been found to have antiepileptogenic properties in rats.[56]
Taking an exogenous ketone supplement, such as Perfect Keto can also help reduce keto flu symptoms. Exogenous ketones help fight fatigue and boost energy levels by raising the ketone levels in your blood. To be clear, ketone supplements aren’t a replacement for the keto diet, but they can help you stay in ketosis when you’re meeting your macros, and provide all day energy.
Run by the Charlie Foundation, this calculator can be helpful when you’re using keto as a therapy to help manage a medical condition. The calculator helps estimate calorie needs based on weight, assists in determining a macro ratio and macros needed per meal, and can calculate macro numbers on the basis of meals and snacks you enter into the system. Also takes into account fluids, supplements, and medications.
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]
As for if you’re dealing with health issues, you really have to defer to your doctor. For instance, if you have kidney disease, you also want to talk to your doctor about appropriate protein intake. If you have heart disease, you can still go low carb, but you may be better off opting for monounsaturated fats (avocados, nuts, and olive oil) over saturated fats (butter and red meat). Everyone’s cholesterol levels respond differently on a low-carb diet, so if yours are going up, switch to unsaturated sources of fats, Spritzler recommends. “In general, this is a diet most people can do. If you have a chronic condition, work with a doctor who understands low-carbohydrate diets to monitor you,” she adds.

Now if you're thinking you'll just handle the problem by brushing and flossing a little more often, guess again. Since the breath odor is coming from metabolic changes and not necessarily a dental-related condition, traditional breath products are not likely to provide long-lasting relief. On the other hand drinking more water intake can do the trick.
You probably hear the most about low-carb eating for weight loss, but for some people, the approach could also help optimize their health, says Schmidt. “Research shows that women who are obese or have metabolic problems [may] do better hormonally on lower carbs,” says Schmidt, pointing out that other outcomes of the diet can include better sleep, mental clarity, and increased satiety. (1)

Conklin's fasting therapy was adopted by neurologists in mainstream practice. In 1916, a Dr McMurray wrote to the New York Medical Journal claiming to have successfully treated epilepsy patients with a fast, followed by a starch- and sugar-free diet, since 1912. In 1921, prominent endocrinologist Henry Rawle Geyelin reported his experiences to the American Medical Association convention. He had seen Conklin's success first-hand and had attempted to reproduce the results in 36 of his own patients. He achieved similar results despite having studied the patients for only a short time. Further studies in the 1920s indicated that seizures generally returned after the fast. Charles P. Howland, the parent of one of Conklin's successful patients and a wealthy New York corporate lawyer, gave his brother John Elias Howland a gift of $5,000 to study "the ketosis of starvation". As professor of paediatrics at Johns Hopkins Hospital, John E. Howland used the money to fund research undertaken by neurologist Stanley Cobb and his assistant William G. Lennox.[10]
During the 1920s and 1930s, when the only anticonvulsant drugs were the sedative bromides (discovered 1857) and phenobarbital (1912), the ketogenic diet was widely used and studied. This changed in 1938 when H. Houston Merritt, Jr. and Tracy Putnam discovered phenytoin (Dilantin), and the focus of research shifted to discovering new drugs. With the introduction of sodium valproate in the 1970s, drugs were available to neurologists that were effective across a broad range of epileptic syndromes and seizure types. The use of the ketogenic diet, by this time restricted to difficult cases such as Lennox–Gastaut syndrome, declined further.[10]
The ketogenic diet is usually initiated in combination with the patient's existing anticonvulsant regimen, though patients may be weaned off anticonvulsants if the diet is successful. Some evidence of synergistic benefits is seen when the diet is combined with the vagus nerve stimulator or with the drug zonisamide, and that the diet may be less successful in children receiving phenobarbital.[18]
Low-carb diets may help prevent or improve serious health conditions, such as metabolic syndrome, diabetes, high blood pressure and cardiovascular disease. In fact, almost any diet that helps you shed excess weight can reduce or even reverse risk factors for cardiovascular disease and diabetes. Most weight-loss diets — not just low-carb diets — may improve blood cholesterol or blood sugar levels, at least temporarily.
“You are literally starving” on an intermittent fasting diet, Keatley says. “Methods such as this are attractive as weight loss can go from one pound a week to four pounds, but this is mostly lean muscle which is essential to healthy functioning as you age and is very hard to get back once it is gone,” he adds. So…it’s not really recommended that you try this unless you hash it out with your doctor or nutritionist to make sure it's a fit for you and your lifestyle.
Have an electronics curfew: According to Harvard University, the blue light from tablets, laptops, and smartphones can seriously interfere with your circadian rhythm, and make it difficult for you to fall asleep (6). Having an electronics curfew (ideally at least two hours before you go to bed) is an excellent way to improve your sleep quality. Why not replace the nightly Instagram, Facebook, and email-checking time with a bedtime ritual that helps you relax and unwind?
The ketogenic diet achieved national media exposure in the US in October 1994, when NBC's Dateline television programme reported the case of Charlie Abrahams, son of Hollywood producer Jim Abrahams. The two-year-old suffered from epilepsy that had remained uncontrolled by mainstream and alternative therapies. Abrahams discovered a reference to the ketogenic diet in an epilepsy guide for parents and brought Charlie to John M. Freeman at Johns Hopkins Hospital, which had continued to offer the therapy. Under the diet, Charlie's epilepsy was rapidly controlled and his developmental progress resumed. This inspired Abrahams to create the Charlie Foundation to promote the diet and fund research.[10] A multicentre prospective study began in 1994, the results were presented to the American Epilepsy Society in 1996 and were published[17] in 1998. There followed an explosion of scientific interest in the diet. In 1997, Abrahams produced a TV movie, ...First Do No Harm, starring Meryl Streep, in which a young boy's intractable epilepsy is successfully treated by the ketogenic diet.[1]

Now if you're thinking you'll just handle the problem by brushing and flossing a little more often, guess again. Since the breath odor is coming from metabolic changes and not necessarily a dental-related condition, traditional breath products are not likely to provide long-lasting relief. On the other hand drinking more water intake can do the trick.
However, there is one caveat with eating more fat (and it is not heart disease). Most fats aren’t readily used as fuel, especially during the first few days of carbohydrate restriction. In fact, animal fats from meat and dairy have to go all the way through your lymphatic system to your heart, muscle cells, and fat cells before they reach the liver.
Lots of apps and websites offer keto diet challenges—basically, a blueprint for the keto diet with a fixed starting and ending point (they typically last for a week to a month, though some may be longer). Speaking of apps, plenty of keto-centric ones are right at your fingertips (a.k.a., your smartphone), like the KetoDiet app, which can help you calculate your macros and track your keto diet effectively.
The ketogenic diet is indicated as an adjunctive (additional) treatment in children and young people with drug-resistant epilepsy.[26][27] It is approved by national clinical guidelines in Scotland,[27] England, and Wales[26] and reimbursed by nearly all US insurance companies.[28] Children with a focal lesion (a single point of brain abnormality causing the epilepsy) who would make suitable candidates for surgery are more likely to become seizure-free with surgery than with the ketogenic diet.[9][29] About a third of epilepsy centres that offer the ketogenic diet also offer a dietary therapy to adults. Some clinicians consider the two less restrictive dietary variants—the low glycaemic index treatment and the modified Atkins diet—to be more appropriate for adolescents and adults.[9] A liquid form of the ketogenic diet is particularly easy to prepare for, and well tolerated by, infants on formula and children who are tube-fed.[5][30]
The modified Atkins diet reduces seizure frequency by more than 50% in 43% of patients who try it and by more than 90% in 27% of patients.[18] Few adverse effects have been reported, though cholesterol is increased and the diet has not been studied long term.[48] Although based on a smaller data set (126 adults and children from 11 studies over five centres), these results from 2009 compare favorably with the traditional ketogenic diet.[18]
Although many hypotheses have been put forward to explain how the ketogenic diet works, it remains a mystery. Disproven hypotheses include systemic acidosis (high levels of acid in the blood), electrolyte changes and hypoglycaemia (low blood glucose).[19] Although many biochemical changes are known to occur in the brain of a patient on the ketogenic diet, it is not known which of these has an anticonvulsant effect. The lack of understanding in this area is similar to the situation with many anticonvulsant drugs.[56]
"I recommend only 5 percent of calories coming from carbs, which usually averages out to less than 30 grams," he says. "I understand why people get nervous and panic, thinking 'Can I even eat a salad?' This is why I recommend tracking only 'net carbs', which are total carbs minus fiber. For example, an avocado has 12 grams of carbs but 10 grams of fiber, which means it has 2 grams of net carbs. Also, green leafy vegetables are very nutritious and contain a lot of fiber, so you can almost eat them as much as you want and stay below your limit.
Ketosis is pretty different from what your body is used to, and this onslaught of symptoms is its way of dealing with carb withdrawal—and adapting, explains Kristen Mancinelli, RD, author of The Ketogenic Diet. “It takes a while, usually a week or two, for the metabolic machinery to shift to fat-burning mode. And you’ll feel pretty crummy while the transition is happening,” she says.

Lots of apps and websites offer keto diet challenges—basically, a blueprint for the keto diet with a fixed starting and ending point (they typically last for a week to a month, though some may be longer). Speaking of apps, plenty of keto-centric ones are right at your fingertips (a.k.a., your smartphone), like the KetoDiet app, which can help you calculate your macros and track your keto diet effectively.
When you’re eating the foods that get you there (more on that in a minute), your body can enter a state of ketosis in one to three days, she adds. During the diet, the majority of calories you consume come from fat, with a little protein and very little carbohydrates. Ketosis also happens if you eat a very low-calorie diet — think doctor-supervised, only when medically recommended diets of 600 to 800 total calories.
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