You can have a completely smooth transition into ketosis, or…not. While your body is adapting to using ketones as your new fuel source, you may experience a range of uncomfortable short-term symptoms. These symptoms are referred to as “the keto flu.” Low-sodium levels are often to blame for symptoms keto flu, since the kidneys secrete more sodium when you’re in ketosis, says Volek. A few side effects:
In addition, there are medical conditions that should make you think twice about starting keto — or at least talk to your doctor before trying it out. Those include people on insulin, as well as those on oral and noninsulin injectable medications for high blood sugar or high blood pressure, says Hultin. Even struggling with GI issues may be a barrier to starting. “One of the side effects of a ketogenic diet is constipation, so if that’s a struggle, there’s serious reason not to go on this relatively low-fiber diet,” says Hultin. Last consideration: If existing personal dietary restrictions require you to avoid foods like soy, eggs, nuts, dairy, or seafood, a ketogenic diet may be too limiting for you. Coming from a place of elimination in an already restrictive diet can make it incredibly tough to follow, she says.
On a ketogenic diet, your entire body switches its fuel supply to run mostly on fat, burning fat 24-7. When insulin levels become very low, fat burning can increase dramatically. It becomes easier to access your fat stores to burn them off. This is great if you’re trying to lose weight, but there can also be other, less obvious benefits, such as less hunger and a steady supply of energy (without the sugar peaks and valleys we can get from high carb meals). This may help keep you alert and focused.
Those issues can be part of what's known as the “keto flu,” Warren says. Other side effects of the keto diet, all of which are tied to carb withdrawal, can include lightheadedness, nausea, mental fog, cramps, and headaches, in addition to tiredness. Luckily, the keto flu doesn't usually last more than a week—which is coincidentally about when people start to see the number on the scale go down, says Warren.
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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]
“People are afraid of fat because they’ve been told that it’ll kill them,” says Mancinelli. What is confusing is that research today remains mixed. Some studies suggest that replacing saturated fat with polyunsaturated fat (and avoiding unhealthy trans fat) is important for mitigating heart disease risk, while others suggest that total fat and types of fat weren’t associated with cardiovascular problems, according to an article published in June 2018 in BMJ. (2) Deciding exactly how to eat then becomes confusing. What is helpful, the authors note, is to remember that food is more than a single nutrient, and it’s the overall quality of the diet that counts. (They do say that high-fat, low-carb diets still need more research to assess their long-term health benefits and risks.)
As mentioned, there are a few reasons why the keto diet usually equals weight-loss gold, says Keatley. For starters, people usually reduce their daily caloric intake to about 1,500 calories a day because healthy fats and lean proteins make you feel fuller sooner—and for a longer period of time. And then there’s the fact that it takes more energy to process and burn fat and protein than carbs, so you're burning slightly more calories than you did before. Over time, this can lead to weight loss.
Sleep enough – for most people at least seven hours per night on average – and keep stress under control. Sleep deprivation and stress hormones raise blood sugar levels, slowing ketosis and weight loss a bit. 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 its own, it’s still worth thinking about.

Cravings: As one begins to eliminate carbohydrates from the diet, it is common to experience carbohydrate cravings. Several suggestions for conquering these cravings are outlined below. However, it should be noted that as the body keto-adapts, hunger and appetite should become suppressed. One interesting study found that when you increase the occupied volume inside of the stomachs of subjects, this led to feelings of perceived fullness.[17] This means by doing things like drinking more water and eating more high volume foods we can improve our feeling of fullness.
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]

Now that ketogenic diets have become popular, many keto hybrid diets have sprung up, including plant-based versions. (One is “ketotarian,” which is predominantly plant-based but includes the option of eggs, ghee, and fish and shellfish.) While this approach can be healthy, Hultin cautions against trying keto as a vegan. “Because you can’t eat beans or lentils on a ketogenic diet, and nuts and seeds are even limited due to their carbohydrate content, you’re really just left with some tofu and will need to rely on low-carb protein powder,” she says. There is a good possibility this won’t pan out. “I don’t see this as a sustainable diet due to the extreme restrictions,” she says.
Here’s what we do know: The keto diet may be useful in treating symptoms of epilepsy, a seizure disorder. “The use of keto in treating epilepsy has the most evidence,” Angelone says. One study conducted by Johns Hopkins Medicine, for example, followed epileptic patients on the keto diet and found that 36 percent of them had a 50 percent reduction in seizures after three months on the diet, and 16 percent were seizure-free. However, experts aren't entirely sure why the keto diet has this affect, she adds.
“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.

Hi 😀 yes I have a question, just starting this Keto diet, so we’re very new at this but my boyfriend had a heart attack 8 years ago so we need to be very careful to not get to high on fat with him. Can he still benefit from this diet. His Doctor said he needs to get some of his weight off he is having a hard time breathing. The Doctor said a low carb diet. But I, we would like to try the Keto diet.


If you're new to keto, watch out for hidden carbs. Generally, dairy products and nuts are a good way to meet your daily fat intake, but know that some of those items may contain more carbohydrates than you think. For example, yogurt topped with nuts may seem like a great keto-friendly snack, but a 5.3 ounce serving of plain yogurt has 12 grams of carbohydrates. Vanilla flavored yogurt has 24 grams of carbohydrates. Add an ounce of cashews, weighing in at nearly nine grams of carbs, and you’re up to 21 to 33 grams of carbs for that snack, which could knock you out of ketosis. Be sure to read nutrition labels carefully and pay careful attention to serving sizes. Track foods using a keto-specific app like Senza or KetoDiet can help you stay within your recommended daily carb intake.


Christopher D. Gardner, PhD; Alexandre Kiazand, MD; Sofiya Alhassan, PhD; Soowon Kim, PhD; Randall S. Stafford, MD, PhD; Raymond R. Balise, PhD; Helena C. Kraemer, PhD; Abby C. King, PhD, “Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women,” JAMA. 2007;297(9):969-977. http://jama.jamanetwork.com/art icle.aspx?articleid=205916.
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.

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]


Diabetic Ketoacidosis: Diabetic ketoacidosis (DKA) is the variation of ketosis that is responsible for deterring society from considering the adoption of a keto diet for beginners. DKA occurs primarily in those suffering from Type 1 diabetes. The inability to secrete insulin prevents ingested carbohydrates (glucose) from entering our insulin-dependent cells (i.e., muscle and adipose tissue) as a substrate for energy production. Due to this induced cellular starvation, the body will begin to produce ketones at an uncontrolled rate.
If you’ve decided to move forward in trying the keto diet, you will want to stick to the parameters of the eating plan. Roughly 60 to 80 percent of your calories will come from fats. That means you’ll eat meats, fats, and oils, and a very limited amount of nonstarchy vegetables, she says. (This is different from a traditional low-carb diet, as even fewer carbs are allowed on the keto diet.)

When dietary carbohydrate is broken down into the energy substrate glucose, thereby raising blood glucose levels, the pancreas is stimulated to secrete insulin (the hormone that stores fat and inhibits ketone production). However, when carbohydrate intake is restricted, insulin remains suppressed, and the body’s primary fuel source shifts from glucose to fat, priming the body to enter a state of ketosis. When fat oxidation/breakdown is increased to a certain extent, ketones are made in the liver through a process known as ketogenesis (i.e., keto + genesis = ketone formation). When carbohydrate intake is restricted, blood glucose and insulin levels decrease, which allows fat stores to be broken down rapidly for energy. Most cells in the body can utilize either fatty acids or ketones for fuel, including the brain, which has shown to be more efficient in the presence of ketones rather than glucose.


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]
Supplemental ketosis: This form of ketosis has recently gained momentum in the field of ketogenic dieting. Supplemental ketosis is a ketogenic state that is achieved through the ingestion of ketogenic supplements. Consuming these substances alone does not mean that an individual is “keto-adapted.” While these products can help during the keto-adaptation period, especially if one is experiencing the “keto-flu,” they will only elicit short-term increases in blood ketone levels. Exogenous ketones can acutely produce benefits similar to the ketogenic diet; however, these products are best used in conjunction with a well-formulated keto diet for beginners, or the very at least, a diet that restricts carbohydrates. The commonly used supplements on the market are medium-chain triglyceride (MCT) oil and exogenous ketones. MCT oil is a fat that, in contrast to other longer-chain fatty acids, travels straight from the intestines to the liver where it is readily metabolized. This allows for ketone production in the liver to occur faster than with other fats (long-chain fatty acids have to travel through the lymph and circulatory systems first). Exogenous ketones are synthetic substances that mimic the ketones produced in our body (endogenous ketones). Exogenous ketones can come in the form of ketone salts or ketone esters.
Thank you so much for the wonderful recipes on your site. I have visited in the past and have happened upon it again. I noticed you put in the post that if anyone had questions that we could ask and so I have a big one that I need advice on if you don’t mind. I have been living low carb for about 2 years now. My weight has fluctuated from 130 to about 118. I am 5’4″ and female, 45 years old and mom to 5 children. My weight went up to 134 which is very uncomfortable to me because I have struggled with an eating disorder and so I really went low carb in an attempt to drop some weight. Well I have, but the problem is that I am restricting too many calories now. I have gotten down to 108 but know that 800 calories Is not enough. My question is about balance. I would not mind gaining some back but have a fear of gaining too much again. I don’t want to go back there. I hiit train most days for about 25 mins. I use to do way too much. Do you have a plan that would balance my calories out so I can incorporate more Low carb options/keto and start eating normal again. I like your ideas and thought process behind all you post so I would appreciate any feed back you could give to me. Thank ML
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