Experts warn that the diet is extremely restrictive and not sustainable, and that it can lead to nutritional deficiencies, high cholesterol, or a serious condition called ketoacidosis. But even before long-term problems set in, many people who try the diet report other unpleasant side effects. These side effects even have a name in the weight-loss world: keto flu.

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.

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]
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.

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]


In general, a low-carb diet focuses on proteins, including meat, poultry, fish and eggs, and some nonstarchy vegetables. A low-carb diet generally excludes or limits most grains, legumes, fruits, breads, sweets, pastas and starchy vegetables, and sometimes nuts and seeds. Some low-carb diet plans allow small amounts of certain fruits, vegetables and whole grains.

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]

Certainly, prioritizing sleep, hydration, and overall healthy habits can keep you from feeling even worse, whether you’re on the keto diet or not. But the experts we spoke with agreed that avoiding ketosis altogether is a smarter way to feel good while you’re trying to lose weight, rather than putting a Band-Aid on something that could have more serious consequences down the road.


That said, it’s a good idea to work with a doctor or registered dietitian before you start eating keto—and continue to check in with them while you adapt to your new diet, recommends David Nico, PhD, author of Diet Diagnosis. Planning ahead can help you steer clear of nutritional deficiencies that can strike when you cut most carbs out of your diet. And doing so might also help minimize your keto flu symptoms.


It is possible to cut back on sugar and carbs—and, yes, lose weight—without experiencing these nasty symptoms, says Sharp. “While you cannot achieve ketosis without a significantly reduced-carb diet, you can absolutely reap a lot of the potential glycemic benefits of a low-carb diet—without some of the downfalls, like keto flu—simply by choosing the right carbs,” she says.
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.
Keto blogs and weight-loss websites recommend taking precautions—like making sure you’re staying hydrated, getting plenty of sleep, and finding ways to manage stress—to reduce the unpleasant effects of the ketogenic diet on your body. Some also recommend electrolytes, ketone supplements, or bone broth (which is high in sodium and other minerals) to replace some of what the body is missing in the early stage of the diet.
Your body uses carbohydrates as its main fuel source. Complex carbohydrates (starches) are broken down into simple sugars during digestion. They're then absorbed into your bloodstream, where they're known as blood sugar (glucose). In general, natural complex carbohydrates are digested more slowly and they have less effect on blood sugar. Natural complex carbohydrates provide bulk and serve other body functions beyond fuel.

Remember, your water and electrolyte intake needs to go up on a keto diet, and dehydration can exacerbate many keto flu symptoms. There’s no hard and fast recommendation for how much water keto dieters should be drinking, Nico says. But in general, you should be sipping enough so that your urine stays clear or pale yellow. As for electrolytes like sodium? A registered dietitian can help you figure out how much more you should be having and the best places to get it. If you're feeling sick and can't see a nutritionist right away, consider mixing a low-carb electrolyte drink into your water.


Sleep enough and minimize stress. Most people benefit from a minimum of seven hours of sleep per night on average. And try to keep stress under control. Sleep deprivation and stress hormones raise blood sugar levels, slowing ketosis and weight loss. Plus they might make it harder to stick to a keto diet and resist temptations. So while handling sleep and stress will not get you into ketosis on their own, they are still worth thinking about.
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