The ketogenic (keto) diet, characterized by its high-fat, very-low-carbohydrate composition, has gained considerable attention as a weight-loss strategy and potential therapy for various health conditions. While proponents tout benefits such as rapid weight loss, improved blood sugar control, and potential neuroprotective effects, it's crucial to understand both the advantages and potential risks associated with this dietary approach.
What is the Keto Diet?
The keto diet is an eating plan that focuses on foods that provide a lot of healthful fats, adequate amounts of protein, and very few carbohydrates. The goal is to get more calories from fat than from carbs. Typically, a keto diet consists of 70-80% of calories from fat, about 20% from protein, and as little as 5% from carbs. This macronutrient ratio shifts the body's primary fuel source from glucose (derived from carbohydrates) to ketones, molecules produced from fat breakdown.
The diet works by depleting the body of its sugar reserves. As a result, it will start to break down fat for energy. This results in the production of molecules called ketones that the body uses for fuel. This metabolic state, known as ketosis, is where the diet’s purported health benefits come from. Once your body processes fats in the liver, it produces ketone bodies, molecules that can be used for energy. However, you can only reach ketosis once your body has used up all its available carbs.
There are several types of keto diet, including the Standard Ketogenic Diet and the Cyclical Ketogenic Diet.
Potential Benefits of the Keto Diet
The ketogenic diet may offer several potential health benefits, including:
Read also: The ultimate guide to keto stews
Weight Loss
The ketogenic diet may help promote weight loss in several ways, including boosting metabolism and reducing appetite. Ketogenic diets consist of foods that fill a person up and may reduce hunger-stimulating hormones. For these reasons, following a keto diet may reduce appetite and promote weight loss.
In a 2013 meta-analysis of 13 different randomized controlled trials, researchers found that people following ketogenic diets lost 2 pounds (lbs) more than those following low fat diets over 1 year. Similarly, another review of 11 studies demonstrated that people following a ketogenic diet lost 5 lbs more than those following low-fat diets after 6 months.
Cutting carbs means you’ll drop water weight, which you’ll see quickly on the scale. After the first couple of weeks, this rapid “weight loss” will slow to a more normal pace. While this initial drop in pounds isn’t fat loss, the fast results can be a motivating factor for many people, helping them continue with the diet. Research also suggests that certain types of ketones released during ketosis may play a role in appetite suppression, which can make it easier to stick to a calorie deficit.
Eating low carb foods might also make it easier for your body to burn fat. According to research from 2022, keto may reduce insulin spikes. Insulin stops lipolysis, the process by which your body breaks down stored fat, so keeping blood sugar levels stable might make losing body fat easier.
Acne Reduction
Acne has several different causes and may have links to diet and blood sugar in some people. Eating a diet high in processed and refined carbohydrates may alter the balance of gut bacteria and cause blood sugar to rise and fall significantly, both of which can adversely affect skin health. According to a 2012 study, by decreasing carb intake, a ketogenic diet could reduce acne symptoms in some people.
Read also: Affordable ketogenic diet tips
Cancer Treatment
Researchers have examined the effects of the ketogenic diet in helping prevent or even treat certain cancers. One study found that the ketogenic diet may be a safe and suitable complementary treatment to use alongside chemotherapy and radiation therapy in people with certain cancers. This is because it would cause more oxidative stress in cancer cells than in normal cells, causing them to die. A more recent study from 2018 suggests that because the ketogenic diet reduces blood sugar, it could also lower the risk of insulin complications. Insulin is a hormone that controls blood sugar that may have links to some cancers.
The idea behind this is related to something called the Warburg effect. This claims that there are metabolic changes in cancer cells that mean they primarily use glucose (carbs) for energy, even when oxygen is available. Theoretically, a keto diet that cuts down on carbs and forces the body to rely on fat for fuel might “starve” cancer cells. This could potentially weaken cancer cells, making them more susceptible to chemotherapy and radiation, while protecting normal cells.
One small 2023 study found a better overall survival rate in participants who continued the keto diet for longer, but experts note that this research is still in its early stages.
Although some research indicates that the ketogenic diet may have some benefit in cancer treatment, studies in this area are limited. Researchers need to carry out more studies to fully understand the potential benefits of the ketogenic diet in cancer prevention and treatment.
Heart Health Improvement
When a person follows the ketogenic diet, it is important that they choose healthful foods. Some evidence shows that eating healthful fats, such as avocados instead of less healthful fats, such as pork rinds, can help improve heart health by reducing cholesterol. A 2017 review of studies of animals and humans on a keto diet showed that some people experienced a significant drop in levels of total cholesterol, low-density lipoprotein (LDL), or bad cholesterol, and triglycerides, and an increase in high-density lipoprotein (HDL), or “good” cholesterol. High levels of cholesterol can increase the risk of cardiovascular disease. A keto diet’s reducing effect on cholesterol may, therefore, reduce a person’s risk of heart complications.
Read also: Your guide to keto-friendly bars
Therefore, it’s perhaps not so much the keto diet itself that directly improves blood markers for cardiovascular health, but rather the types of fats you’re eating on a daily basis.
However, the review concluded that the positive effects of the diet on heart health depend on diet quality. Therefore, it’s important to eat healthful, nutritionally balanced food while following the keto diet.
Brain Health
Some studies, such as this 2019 review, suggest the ketones that generate during the keto diet provide neuroprotective benefits, which means they can strengthen and protect the brain and nerve cells. For this reason, a keto diet may help a person prevent or manage conditions such as Alzheimer’s disease. However, more research is necessary into a keto diet’s effects on the brain.
Epilepsy Management
The ratio of fat, protein, and carbs in a keto diet alters the way the body uses energy, resulting in ketosis. Ketosis is a metabolic process during which the body uses ketone bodies for fuel. The Epilepsy Foundation suggest that ketosis can reduce seizures in people with epilepsy - especially those who have not responded to other treatment methods. More research is necessary on how effective this is, though it seems to have the most effect on children who have focal seizures. A 2019 review supports the hypothesis that a keto diet can support people with epilepsy. The ketogenic diet may reduce epilepsy symptoms by several different mechanisms.
Originally developed in the 1920s as a treatment for patients with severe drug-resistant epilepsy, the keto diet has been shown to be effective for reducing seizures in extreme cases. Scientists believe the diet decreases seizures by making less glucose available to fuel neurons.
Polycystic Ovary Syndrome (PCOS) Improvement
Polycystic ovary syndrome (PCOS) is a hormonal disorder that can lead to excess male hormones, ovulatory dysfunction, and polycystic ovaries. A high-carbohydrate diet can cause adverse effects in people with PCOS, such as skin problems and weight gain. There are not many clinical studies on the ketogenic diet and PCOS. One pilot study from 2005 examined five women over 24 weeks. The researchers found that a ketogenic diet improved several markers of PCOS, including: weight loss, hormone balance, ratios of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and levels of fasting insulin. A different review of studies from 2019 found that a keto diet had beneficial effects for people with hormonal disorders, including PCOS and type 2 diabetes. However, they did also caution that the studies were too diverse to recommend a keto diet as a general treatment for PCOS.
Blood Sugar Management in Type 2 Diabetes
There’s been a lot of research on keto for type 2 diabetes, and for good reason. Low carb diets have been a mainstay of diabetes management, and they were recommended well before injectable insulin became available. So while low carb diets for diabetes are nothing new, keto provides a novel approach by upping the fat content. It’s well established in the research that keto and low carb diets can help stabilize blood sugar, but there may actually be more potential benefits at play.
One 2019 study found that a keto diet reversed type 2 diabetes in some participants, and after a 2-year follow-up, many participants had improvements in their diabetes blood markers. Among participants, there was a diabetes remission rate of 17.6%.
Potential Risks and Side Effects
While the ketogenic diet may have a range of health benefits, staying on the ketogenic diet long-term can have an adverse effect on health, including an increased risk of the following health problems:
Kidney Stones
Kidney stones are a well-noted potential side effect of the ketogenic diet. Past research observed that among children following the keto diet as a treatment for epilepsy, 13 out of 195 subjects developed kidney stones. Children supplementing with potassium citrate in the study noticed a decreased likelihood of kidney stones. Speak with your healthcare practitioner about supplementing if kidney stones are a concern.
Excess Protein in the Blood
Mineral and Vitamin Deficiencies
Because the keto diet limits carbs to just 50 g, it doesn’t leave room to include many fruits or vegetables. These are your body’s primary source of essential vitamins and minerals, all of which play a role in keeping your cells healthy. When carbohydrate intake is low, fiber consumption tends to be low, too. This doesn’t come as a surprise when you consider fruits, whole grains, and starchy vegetables are decreased in your diet. This can lead to one especially uncomfortable side effect. Another possible nutrient deficiency: potassium, a mineral important for both electrolyte balance and blood pressure control, notes MedlinePlus. Inadequate intake of potassium is likely when consumption of fruits and starchy vegetables are decreased.
If you’re trying keto, you can mitigate some of these deficiencies by eating plenty of low carb vegetables like leafy greens, broccoli, asparagus, and zucchini. It’s also a good idea to work with a registered dietitian if you’re planning on following the diet for an extended period of time.
A Build Up of Fat in the Liver
Keto Flu
The keto diet can cause adverse side effects that many people know as keto flu. These adverse effects may include: constipation, fatigue, low blood sugar, nausea, vomiting, headaches, and a low tolerance for exercise. These symptoms are especially common at the beginning of the diet as the body adjusts to its new energy source.
Suddenly and drastically reducing carbohydrates sets your body up for a double whammy of sorts,” says Yawitz. “The brain’s favorite fuel is glucose, which is most easily created from carbohydrates. In very low carb diets, the brain has to adjust to using ketones from digested fats for energy. To add to this discomfort, your kidneys release more electrolytes as insulin levels fall.”
Additionally, your total body water decreases as carbohydrates become depleted on a keto diet, notes Clark. The result? What’s known as the keto flu, which can cause constipation, nausea, headache, fatigue, irritability, cramps, and other symptoms. Don’t fret: Many of these symptoms last only a few days to weeks. Make sure to drink plenty of water to help your body cope with these symptoms. And call your doctor if symptoms - especially nausea - are prolonged, advises Yawitz.
Digestive Issues
Staying low carb means you won’t be eating many beans, lentils, or whole grains, which are all good sources of fiber. This can lead to constipation and slow digestion. Consuming so much fat can also be tough on your digestive system. Many people who try keto experience gastrointestinal (GI) issues like diarrhea, cramping, bloating, and stomach upset. Other causes of diarrhea on the keto diet include lack of fiber (fiber helps ward off diarrhea by bulking up stool) and processed low-carb foods like shakes and bars that may contain sugar alcohols. These sugar alcohols can ferment in the gut and cause gastrointestinal discomfort.
Potential Cardiovascular Risks
While we discussed the possible benefits on heart health earlier, we also touched on the risks. If you’re eating a keto diet that’s high in sources of saturated fat - like meat, cheese, and butter - you’re at risk of harming your heart health. Saturated fat is known to increase levels of LDL (bad) cholesterol, which can clog your arteries. This is associated with heart and cardiovascular disease.
The ketogenic diet doesn’t put a cap on saturated fat, which has been associated with adverse health effects. If you have high cholesterol or other risk factors for heart disease, you should speak with your doctor before beginning the keto diet. This is because the diet may - but doesn't have to - include large amounts of saturated fat. Some studies have shown increases in cholesterol and triglycerides in people following the diet, while other research reveals that the keto diet may actually decrease heart disease risk.
Difficulty in Adherence and Long-Term Sustainability
Sticking to a keto diet can be tricky, and it’s not easy to do long term. There’s also no long-term data on its safety, so it’s not something you’d want to do without the supervision of a healthcare professional. Following a keto diet requires a lot of meal planning and food preparation, and this can be incredibly challenging for people with busy jobs and families. It’s also hard to find keto-friendly options at restaurants and social gatherings, so some people find it negatively affects their social life. If you find that a lower carb style of eating feels good for your body, trying a more relaxed approach - like a low carb Mediterranean style diet - might be a simpler, more sustainable choice.
Muscle Loss
Muscle loss on the ketogenic diet is an ongoing area of research,” says Edwina Clark, RD, a dietitian in private practice in San Francisco. “Small studies suggest that people on the ketogenic diet lose muscle even when they continue resistance training. This may be related to the fact that protein alone is less effective for muscle building than protein and carbohydrates together after exercise.” Meanwhile, according to one small study, published in the March 2018 issue of Sports, people who followed the keto diet for three months lost about the same amount of body fat and had about the same muscle mass changes as people following normal diets. Yet the folks on keto did lose more leg muscle.
Loss of muscle mass as we age has a number of serious consequences,” notes Clark. “Muscle is metabolically active and helps boost daily energy expenditure and mitigate age-related weight gain.” Losing muscle mass can decrease functional strength and heighten the risk of falls, notes Clark. Falls are the top cause of death from injury in older populations, according to the Institute of Medicine Division of Health Promotion and Disease Prevention.
Low Blood Sugar Risk
Carbohydrates help control blood sugar levels, which are of particular importance for people with diabetes. A study published in Diabetic Medicine in May 2018 found that while a keto diet may help control HbA1C levels (a two- to three-month average of blood sugar levels), the diet may also cause episodes of hypoglycemia, which is a dangerous drop in blood sugar. The same goes for people with type 2 diabetes. While some preliminary research suggests the keto diet may be safe and effective for certain people with type 2 diabetes, there’s still the risk of low blood sugar, especially for those on insulin, and the keto diet omits certain food groups known to benefit those with this disease. For example, research highlights the importance of whole grains for controlling weight as well as episodes of high blood sugar. Whole grains are off-limits on the ketogenic diet.
Yo-Yo Dieting Potential
Rapid, significant weight loss [at the beginning of the diet] is a common side effect of the keto diet because of the water losses that occur as carbohydrate stores are depleted,” says Clark. Sticking with such a restrictive diet long-term can be difficult, however, and leave you open to weight re-gain, and the cycle of yo-yo dieting. Chronic yo-yo dieting appears to increase abdominal fat accumulation and diabetes risk,” notes Clark.
Studies have shown that the ability to stick to a diet is more important for long-term success than the type of diet that’s followed,” says Yawitz. “Keto is incredibly restrictive and is particularly tough for those who have frequent social engagements or are prone to carb cravings.”
Electrolyte Imbalance
Suddenly and drastically reducing carbohydrates sets your body up for a double whammy of sorts,” says Yawitz. “The brain’s favorite fuel is glucose, which is most easily created from carbohydrates. In very low carb diets, the brain has to adjust to using ketones from digested fats for energy. To add to this discomfort, your kidneys release more electrolytes as insulin levels fall.”
Bad Breath
Considered a symptom of the keto flu, your breath on this diet often smells fruity at first. This is because acetone is a by-product of ketosis and is eliminated mostly through the lungs and the breath, according to research. Acetone is a type of ketone known for its fruity aroma in smaller concentrations. It’s hard to say exactly how long it will last as it depends on the person, but it’s common for someone to experience this side effect for a few weeks,” says Asche.
Menstrual Irregularities
Periods may become irregular or completely stop on the keto diet,” says Yawitz. “This is more due to rapid weight loss than the diet itself and happens because of drops in gonadotropin-releasing hormone, follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone.” Long-term disruption of menstruation can bring on serious side effects, including low bone density. This is because estrogen is very important to bone health. Studies have also found that prolonged menstrual irregularity increases risk for cardiovascular disease, depression, anxiety, and sexual dysfunction. It’s important to contact your ob-gyn if your cycles become irregular or if you stop having periods.
Low Blood Sodium
When you start the keto diet, you lose sodium and other electrolytes in the urine due to reductions in insulin,” says Yawitz. “This is a major contributor to symptoms of keto flu.” So it’s important to replenish sodium through the diet, especially if you exercise or sweat a lot. This can help ward off more serious side effects that are seen with long-term sodium deficiencies,” says Yawitz. These include lethargy and confusion - and in extreme cases, seizures, coma, and death, according to the Mayo Clinic.
Contraindications
Some populations should avoid the keto diet, including: people with diabetes who are insulin-dependent, people who have eating disorders, those with kidney disease or pancreatitis, and women during pregnancy and breastfeeding. People who take a type of medication called sodium-glucose cotransporter 2 (SGLT2) inhibitors for type 2 diabetes should also not follow a keto diet. This medication increases the risk of diabetic ketoacidosis, a dangerous condition that increases acidity in the blood.
Important Considerations
- Consult a Healthcare Professional: It is important to discuss any intended diet plan with a doctor, dietitian, or trusted healthcare provider, especially for people who are trying to manage a health problem or disease. People looking to start the keto diet should seek consultation with a doctor and check if they have diabetes, hypoglycemia, heart disease, or any other health conditions to ensure the keto diet is a safe eating pattern. The best course of action is to proceed with caution and consult a professional before diving in. If you have a medical condition or are on medications, you should always consult with your doctor before beginning a ketogenic diet.
- Focus on Nutrient-Dense Foods: When following the ketogenic diet, it's crucial to prioritize nutrient-dense foods, such as non-starchy vegetables, healthy fats (avocados, olive oil, nuts, and seeds), and lean protein sources.
- Monitor Cholesterol Levels: Regularly monitor cholesterol levels, particularly LDL ("bad") cholesterol, as the high-fat content of the keto diet may impact lipid profiles.
- Stay Hydrated: Adequate hydration is essential, especially during the initial stages of the keto diet, to combat dehydration and electrolyte imbalances.
- Consider the Long-Term Implications: Keep in mind that studies on the long-term benefits of the ketogenic diet are lacking. It is unclear whether maintaining this diet over more extended periods is more beneficial than less restrictive healthful eating patterns.