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]
^ 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.
Undesirable symptoms may show up in the first few days after changing what you eat. But this should not be the deciding factor when choosing what to put on your plate. Ideally, you should have the most comprehensive and nutritionally dense diet possible, and the Mediterranean and DASH diets have the best evidence to support living a long and healthy life.
As low-carb dietitian Franziska Spritzler, RD, CDE, who’s based in Orange County, California, points out, when you cut back on carbs, blood sugar and insulin levels generally go down, which can be a good thing for some people. “Carbs are broken down into glucose, which raises your blood sugar and prompts your pancreas to produce insulin to drive sugar into your cells,” says Spritzler. “When you’re overweight or obese, your blood sugar goes up and your pancreas sends out insulin, but your cells may not be responsive, leading your pancreas to overproduce insulin,” she says. High insulin increases hunger and prompts fat storage, she explains.

The ketogenic diet is a high-fat, adequate-protein, low-carbohydrate diet that in medicine is used primarily to treat difficult-to-control (refractory) epilepsy in children. The diet forces the body to burn fats rather than carbohydrates. Normally, the carbohydrates contained in food are converted into glucose, which is then transported around the body and is particularly important in fueling brain function. However, if little carbohydrate remains in the diet, the liver converts fat into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as an energy source. An elevated level of ketone bodies in the blood, a state known as ketosis, leads to a reduction in the frequency of epileptic seizures.[1] Around half of children and young people with epilepsy who have tried some form of this diet saw the number of seizures drop by at least half, and the effect persists even after discontinuing the diet.[2] Some evidence indicates that adults with epilepsy may benefit from the diet, and that a less strict regimen, such as a modified Atkins diet, is similarly effective.[1] Potential side effects may include constipation, high cholesterol, growth slowing, acidosis, and kidney stones.[3]
Turns out, what’s low carbohydrate for one person isn’t for another. “There’s no medical definition of what low carb is,” says Columbus, Ohio–based Kelly Schmidt, RD. Basically, it’s reducing the number of carbs you eat from your norm. In general, however, a low-carb diet may include 50 to 100 grams (g) of carbohydrates per day, she says. Below that is considered a ketogenic diet, while 100 to 200 g of carbohydrates per day is a moderate-carb diet.
A small Feb. 20, 2017, study looked at the impact of a six-week ketogenic diet on physical fitness and body composition in 42 healthy adults. The study, published in the journal Nutrition & Metabolism, found a mildly negative impact on physical performance in terms of endurance capacity, peak power and faster exhaustion. Overall, researchers concluded, “Our findings lead us to assume that a [ketogenic diet] does not impact physical fitness in a clinically relevant manner that would impair activities of daily living and aerobic training.” The “significant” weight loss of about 4.4 pounds, on average, did not affect muscle mass or function.

If you feel as if you’re starving, you’re likely to feel tired and want to give up your diet. But a ketogenic diet should not result in hunger, making it sustainable and possibly making you feel great. So eat enough protein foods and low-carb veggies, with enough added fat to feel satisfied. If you’re hungry all the time, check that you are getting adequate amounts of protein at most meals and, if so, add more fat to your meals (like more butter, more olive oil, or some delicious sauces). Our keto recipes have plenty of fat included, but you can adjust up or down, according to your own needs.
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