Ketosis: Symptoms, Benefits, Risks, and More

If you research different ways to lose weight, you’ll come across various diets and lifestyle tweaks to turn your body into a fat-burning machine.

Increasing the intensity and frequency of your exercise routine is one way to lose body fat and trim your trouble spots, but it’s not the only way. You can also burn more fat through a metabolic state called ketosis, which is the mechanism behind many low-carb diets, including the ketogenic diet and the Atkins diet.

Understanding what ketosis is and learning how to achieve this state can help you whip your body into shape.

But before you attempt to achieve ketosis, you should know a few things about the process, including its potential health risks.

Food is your body’s primary source of energy, and three main nutrients in foods supply your body with this energy. These are carbohydrates, fat, and protein. Typically after eating a meal, your body will first break down carbohydrates from foods, and then fat and protein. Ketosis is a natural metabolic state that occurs when your body doesn’t have enough carbs (or glucose) for energy, so it burns fat instead.

Ketosis happens when your carbohydrate intake is low. As your body breaks down fat, it produces an acid called ketones or ketone bodies, which becomes your body and brain’s main source of energy.

Because ketosis shifts your metabolism and relies on fat for energy, your body can burn fat at a higher rate. Translation? You may reach your weight loss goal sooner than if you didn’t cut carbs at all.

Putting — and then keeping — your body in ketosis isn’t exactly easy. You’ll need to severely minimize your intake of carbohydrates, eating no more than 20 to 50 grams (g) of carbs per day to get there and stay there. A single medium pear, for example, contains 26 g of carbs, and even foods that aren’t generally considered high in carbs — such as nuts and nonstarchy veggies — contain a small amount of carbohydrates, and so will need to be limited or avoided on this plan.

If you’re following the keto diet, you will need protein, but you should limit your intake to about 20 percent of your total daily calories. (1) This is important because when you consume more protein than you need, your body converts the excess protein into carbs through a process called gluconeogenesis. This process pushes your body out of ketosis.

Another dietary approach that’s gaining popularity nowadays is called intermittent fasting and is based on skipping food for limited, planned periods of time. Intermittent fasting will not put you into ketosis on its own. Some people combine intermittent fasting with a keto diet — but you should know this approach hasn’t been studied or proven to work for weight loss.

In addition to following a keto diet, you can talk to your doctor about adding supplements, such as exogenous ketones, to put and help keep your body in ketosis, according to a study from 2017.

Checking your ketone level is one way to know if you’re in ketosis. This metabolic state usually kicks in after three or four days of restricting your carbohydrate intake. You don’t have to visit a doctor to measure your level. Pick up a ketone urine test from a nearby drug store, or use a blood sugar meter that’s capable of measuring ketones.

A normal blood ketone level is under 0.6 millimoles per liter (mmol/L). (2) Any level higher than this can indicate a state of ketosis.

Physical signs and symptoms of ketosis include:

• Weight loss
• Loss of appetite
• Increased energy, though energy may be decreased in the first few weeks on the diet
• Fruity-smelling breath (halitosis)
• Constipation or diarrhea

Many of these symptoms are associated with what people call the “keto flu.” Experts say symptoms should subside within two weeks.

Following a keto diet — a very low-carb, high-fat diet — focuses on replacing carbohydrates with healthy fats, and purposely forces the body into ketosis for weight loss. Keep in mind, this diet doesn’t only focus on eating fewer carbs. It also focuses on eating more real foods and fewer processed foods.

With this diet, about 75 percent of your daily calories come from fat, 20 percent from protein, and 5 percent from carbohydrates. Following a typical keto diet food list, you can eat certain foods freely while you’ll need to limit or totally avoid other foods.

Foods to eat on the keto diet include:

• Meat, including beef, lamb, pork, poultry, fish, and seafood (preferably wild-caught)
• Eggs
• Cheese
• Healthy oils, such as olive oil, avocado oil, or coconut oil (just keep in mind that although coconut oil is permitted on the keto diet, it is linked with raising LDL, or “bad,” cholesterol levels)
• Avocados
• Nonstarchy vegetables, like celery, asparagus, leafy greens, cucumber, and zucchini
• Nuts and seeds

Foods to avoid on the keto diet include:

• Grains, such as rice, quinoa, white potatoes, pasta, bread, and pizza
• Processed foods
• Artificial sweeteners
• Milk
• High-carb fruit, including bananas, pineapples, tangerines, and grapes
• Refined oils

One possible benefit of the ketogenic diet is that you may lose more weight compared with other diets. One study of 17 obese men found that a high-protein, low-carb ketogenic diet over a four-week period helped reduce hunger, resulting in lower food intake and more weight loss compared with a high-protein, medium-carbohydrate nonketogenic diet. (3)

Other research further supports the potential benefits of this diet. For example, preliminary studies link following the keto diet to reduced symptoms of Alzheimer’s disease. (4) Previous research suggests it may also help reverse metabolic syndrome, may help manage Parkinson’s disease, has been proven to help control seizures in children with epilepsy, and, according to the results of a small pilot study, may potentially even improve symptoms of polycystic ovary syndrome (PCOS). (5,6,7)

But some research exposes the potential health risks of the keto diet. For example, a low-carbohydrate, high-fat diet can be unhealthy due to the risk of increasing bad cholesterol and triglycerides. (8) One study on mice even suggests that eating a low-carbohydrate diet could lead to insulin resistance, increasing the risk for type 2 diabetes. (9)

It’s also important to note there have been no long-term studies on the ketogenic diet, nor has there been research that details what may happen to the body if it’s in a constant state of ketosis itself. But given how the body needs carbs to function properly, diets that are based on eliminating or sharply reducing this nutrient while adding fat to your diet may lead to nutritional deficiencies, and supplements and multivitamins are recommended because you’re cutting out entire food groups, warns Alyssa Rothschild, RDN, who is in private practice in Jersey City, New Jersey.

Rothschild further explains how following a ketogenic diet for extended periods of time could also lead to osteopenia, which is a precursor to osteoporosis, a disease that’s characterized by bone loss.

“When the body is in ketosis, it lowers the blood pH level, causing the blood to become acidic. To counter this, the body takes calcium away from the bones,” she says. “The increased acidity in the body also increases uric acid, which can lead to the formation of kidney stones.” Therefore, it goes without saying that due to the stress that an extremely low-carb diet can have on the body, those with kidney damage shouldn’t try to achieve ketosis or attempt the ketogenic diet.

Also worth noting is women who are pregnant or breast-feeding, people on certain diabetes medication and insulin, those with a low body mass index (BMI), children, individuals with gallstones, people who have had their gallbladder removed, (10) and anyone with a history of disordered eating should not try the ketogenic diet.

The long-term effects of constant ketosis haven’t been thoroughly investigated. But it appears to be generally safe for most people, at least as a short-term weight-loss solution.

Again, it’s important to note that this state can cause a high level of ketones in the bloodstream, which can make the blood acidic, a dangerous medical state.

Everyone’s body responds differently to ketosis. So while some people are able to produce insulin during ketosis to slow down ketone production and avoid a toxic level, others can’t. Ketosis becomes dangerous when blood turns acid. Always speak with your healthcare provider before making any changes to your diet.

Although more research is needed, there is some evidence that following the ketogenic diet and achieving ketosis may be beneficial if you’re living with type 2 diabetes and need to manage your symptoms. Limiting carbohydrate intake is crucial with type 2 diabetes because too many carbs can increase blood glucose levels, which can damage blood vessels and lead to vision problems, kidney problems, and nerve problems.

Because you can reach ketosis by restricting your carb intake, this diet may lower your blood glucose levels naturally. And if you’re overweight and living with diabetes, eating fewer carbs may help you lose excess pounds, which is another way to gain control of your blood glucose.

Ketosis is an option for many people with type 2 diabetes because they still produce insulin, which helps their body maintain a safe level of ketones in the blood. If you’re considering trying ketosis or the ketogenic diet with type 2 diabetes, be sure to consult your healthcare provider first to ensure it’s safe for you. This eating approach may interfere with some types of diabetes medication or be inappropriate for you if you have certain diabetes complications, such as kidney damage.

Also, achieving ketosis with type 1 diabetes could cause dangerous complications. Therefore, if you have type 1 diabetes, you’ll want to avoid putting your body in ketosis to avoid this potentially life-threatening health emergency.

These words sound similar, but there’s a difference between ketosis and diabetic ketoacidosis. Whereas ketosis is a metabolic response, ketoacidosis is a serious, life-threatening complication of diabetes.

Diabetic ketoacidosis occurs when ketone levels become too high, due to a lack of insulin, and poison the body. This condition can happen to anyone with diabetes, but it is more common in people with type 1 diabetes because their bodies don’t make insulin. In the event that their ketone level rises, their bodies are unable to produce insulin to slow down this production. If left untreated, this condition can lead to a diabetic coma or death.

Signs of diabetic ketoacidosis include a high blood glucose level, a high ketone level, dehydration, frequent urination, nausea, difficulty breathing, and dry skin. If you have poorly managed type 1 or type 2 diabetes, test your blood glucose level regularly before and after meals, and make sure you check your ketone level whenever your blood sugar is higher than 240 milligrams per deciliter (mg/dL). (11)

A ketone level between 1.6 and 3.0 mmol/L is high and increases the risk of diabetic ketoacidosis. (12) Drinking fluids and taking your insulin can bring down your ketone level. If your level doesn’t decrease or continues to rise, go to the hospital. A ketone level higher than 3.0 mmol/L is a medical emergency.

Some people intentionally achieve ketosis to lose weight by eating a low-carb, high-fat diet. If you don’t want to go into ketosis, you can prevent or treat ketosis by eating a balanced diet, which includes carbs, fat, and protein, and by not skipping meals.

Make sure your carbohydrate intake is 45 to 65 percent of your total daily calories, fat 20 to 35 percent of your total daily calories, and protein 10 to 35 percent of your total daily calories. In other words, if you eat a 2,000-calorie diet, no more than 1,300 of your calories should come from carbs. (13)

Shifting your metabolism and achieving ketosis may speed up weight loss in the short term and result in other health benefits, like more energy and a lower blood pressure. But while ketosis is a preferred nutritional state for some people, it isn’t recommended for everyone — and it’s not a good long-term eating approach due to its restrictive nature, which may lead to potentially dangerous nutritional deficiencies.

Before trying to achieve ketosis, be sure you talk to your doctor to make sure your medication or any underlying health issues won’t put you at risk for further health issues or potentially a health emergency.