The remaining calories in the keto diet come from protein — about 1 gram (g) per kilogram of body weight, so a 140-pound woman would need about 64 g of protein total. As for carbs: “Every body is different, but most people maintain ketosis with between 20 and 50 g of net carbs per day,” says Mattinson. Total carbohydrates minus fiber equals net carbs, she explains.
Although many people find that their energy and stamina improve on a keto lifestyle, trying to do too much in the early stages can worsen keto flu symptoms. Well-known ketogenic researcher Dr. Steve Phinney has conducted studies in endurance athletes as well as obese individuals demonstrating that physical performance decreases during the first week of very-low-carb eating. Fortunately, his research also shows that by week 4, people typically perform better than before they started keto.
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).

So, to combat this decrease in sodium, the simple answer is to take in a bit more salt as sodium deficiency is also a huge issue. If you’re afraid to eat too much salt, then rest assured that if you’re cutting out all the junk food, you’re already consuming way less salt than before (even bread contains salt so you were probably eating way way more sodium before).
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.

That said, there isn’t an agreement that a low-carb diet is superior to any other kind of diet or that it’s healthier long term. A review in the December 2015 issue of Diabetes Therapy that looked at the diet among those with diabetes noted that when it comes to weight loss, a low-carb diet performs no better than other higher-carb diets; and that it doesn’t produce better glycemic control, either. (5) Another report in Diabetes Care also found that over one year, those on a low-carb diet lost weight faster than those on a low-fat one, but after a year, weight loss and A1C levels (an average of blood glucose over about three months) were remarkably similar. (6)

Meat – like grass-fed selections – and fresh veggies are more expensive than most processed or fast foods. What you spend on keto-friendly foods will vary with your choices of protein source and quality. You can select less-expensive, leaner cuts of meat and fatten them up with some oil. Buying less-exotic, in-season veggies will help keep you within budget.
The most science-backed performance-boosting supplements, such as creatine monohydrate, beta-alanine, and caffeine, are all A-OK on the ketogenic diet. So, if you take a pre-workout, you should be able to continue without issue. I would also recommend gulping down some bouillon before your session to ensure your sodium and magnesium levels are on point.

Magnesium is another important mineral that can make your transition to ketosis much easier. Although you won’t lose much magnesium while you are restricting carbohydrates, it is essential for helping you prevent and treat cramps, improve sleep quality, and increase insulin sensitivity. To get a decent dose of magnesium, make sure you add some pumpkin seeds, almonds, and spinach to your keto diet.

From a genetic perspective, certain people are less metabolically flexible because they have genetic variations (e.g., insufficient production of specific enzymes) that make it more difficult for them to adapt to the ketogenic diet. In contrast, those who are quick keto-adapters may be gifted with genes that enhance their ability to switch between fuel sources more efficiently.


Many people take MCT oil and exogenous ketones when they start a Keto diet in order to boost their ketone levels. However, if you’re unused to taking these Keto supplements, then they can cause you to have the runs pretty badly. So make sure to start with a small amount at first (a few grams of ketone salts per day OR 1/2 teaspoon of MCT oil). And then gradually increase your intake as your stomach adjusts to it.
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.
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 has been studied in at least 14 rodent animal models of seizures. It is protective in many of these models and has a different protection profile than any known anticonvulsant. Conversely, fenofibrate, not used clinically as an antiepileptic, exhibits experimental anticonvulsant properties in adult rats comparable to the ketogenic diet.[58] This, together with studies showing its efficacy in patients who have failed to achieve seizure control on half a dozen drugs, suggests a unique mechanism of action.[56]

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.[54]
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]
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.
The ketogenic diet is calculated by a dietitian for each child. Age, weight, activity levels, culture, and food preferences all affect the meal plan. First, the energy requirements are set at 80–90% of the recommended daily amounts (RDA) for the child's age (the high-fat diet requires less energy to process than a typical high-carbohydrate diet). Highly active children or those with muscle spasticity require more food energy than this; immobile children require less. The ketogenic ratio of the diet compares the weight of fat to the combined weight of carbohydrate and protein. This is typically 4:1, but children who are younger than 18 months, older than 12 years, or who are obese may be started on a 3:1 ratio. Fat is energy-rich, with 9 kcal/g (38 kJ/g) compared to 4 kcal/g (17 kJ/g) for carbohydrate or protein, so portions on the ketogenic diet are smaller than normal. The quantity of fat in the diet can be calculated from the overall energy requirements and the chosen ketogenic ratio. Next, the protein levels are set to allow for growth and body maintenance, and are around 1 g protein for each kg of body weight. Lastly, the amount of carbohydrate is set according to what allowance is left while maintaining the chosen ratio. Any carbohydrate in medications or supplements must be subtracted from this allowance. The total daily amount of fat, protein, and carbohydrate is then evenly divided across the meals.[37]
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.

^ 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.


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.
For your body to adapt to carbohydrate restriction, it must make many changes from the cellular level to the hormonal level. This process is synonymous with the adjustment period we go through after ending a relationship with someone we love very much. And just like with our first breakup, breaking up with carbohydrates can cause a laundry list of symptoms called the keto flu.

Many people take MCT oil and exogenous ketones when they start a Keto diet in order to boost their ketone levels. However, if you’re unused to taking these Keto supplements, then they can cause you to have the runs pretty badly. So make sure to start with a small amount at first (a few grams of ketone salts per day OR 1/2 teaspoon of MCT oil). And then gradually increase your intake as your stomach adjusts to it.
Although you'll be cutting way back on carbohydrates and sugar, some fruits are still okay to eat on the keto diet (though you'll still want to be mindful about quantity in order to remain in ketosis). The fruits that make the cut contain far fewer carbs than their off-limits cousins such as apples, pears, bananas, pineapples, papayas, grapes, and fruit juices in general.
The day before admission to hospital, the proportion of carbohydrate in the diet may be decreased and the patient begins fasting after his or her evening meal.[19] On admission, only calorie- and caffeine-free fluids[37] are allowed until dinner, which consists of "eggnog"[Note 8] restricted to one-third of the typical calories for a meal. The following breakfast and lunch are similar, and on the second day, the "eggnog" dinner is increased to two-thirds of a typical meal's caloric content. By the third day, dinner contains the full calorie quota and is a standard ketogenic meal (not "eggnog"). After a ketogenic breakfast on the fourth day, the patient is discharged. Where possible, the patient's current medicines are changed to carbohydrate-free formulations.[19]

The most science-backed performance-boosting supplements, such as creatine monohydrate, beta-alanine, and caffeine, are all A-OK on the ketogenic diet. So, if you take a pre-workout, you should be able to continue without issue. I would also recommend gulping down some bouillon before your session to ensure your sodium and magnesium levels are on point.


"Plenty of people jump right in, thinking all they have to do is cut carbs and increase fat. All of a sudden, they hit a wall and get 'keto flu.' They feel tired, lethargic, and experience headaches," Wittrock says. "The primary reason they get these symptoms is lack of the three primary electrolytes: sodium, potassium, and magnesium. If you're deficient in any of these, you'll suffer mentally and physically. This is the single biggest reason people fail on the keto diet."
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]
Why the heck does it happen? Normally, the body uses glucose—or sugar—as its main source of energy. When you cut your carbs below 50 grams per day (the typical threshold for a ketogenic diet), you enter a metabolic state called ketosis: Instead of burning carbs for fuel, your body begins burning ketones—an alternative fuel source that the liver makes by breaking down fat. In turn, this can make you feel run down.
Many ketogenic dieters also swear by MCT oil. (MCT simply stands for medium chain triglycerides.) MCT's energy-sustaining powers can be explained as follows: When MCT oil is metabolized in the body, it behaves more like a carbohydrate than a fat. Unlike other fats, MCT oil does not go through the lymphatic system. Instead, it is transported directly to the liver where it is metabolized so it releases energy like a carbohydrate and creates lots of ketones (which can be used for fuel) in the process.
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]
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.

If you’ve recently switched to the keto diet and you’re feeling drowsy, achy, nauseous, dizzy, and irritable, don’t worry. These symptoms are your body’s natural reaction to removing carbs from your diet, and while it may have you second guessing your keto diet decision, we promise you these keto flu symptoms will pass. Stick with it, and soon you’ll be reaping the energizing, fat-burning rewards that come with ketosis.

These affect your brain and spine, as well as the nerves that link them together. Epilepsy is one, but others may be helped by a ketogenic diet as well, including Alzheimer’s disease, Parkinson’s disease, and sleep disorders. Scientists aren’t sure why, but it may be that the ketones your body makes when it breaks down fat for energy help protect your brain cells from damage.
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