A 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.
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. When the body burns fats, it can also lead to weight loss.
There are several types of keto diet, including the Standard Ketogenic Diet and the Cyclical Ketogenic Diet.
In this article, we explain the benefits of the keto diet, as well as its risks.
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.
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.
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.
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.
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.
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.
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.
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.
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)
- 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.
The ketogenic diet may have a range of health benefits. However, 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
- excess protein in the blood
- mineral and vitamin deficiencies
- a build up of fat in the liver
The keto diet can cause adverse side effects that many people know as keto flu. These adverse effects may include:
These symptoms are especially common at the beginning of the diet as the body adjusts to its new energy source.
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
- 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.
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.
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.
A ketogenic diet restricts or severely limits carbohydrates. However, some carbohydrates provide health benefits. For a less restrictive dietary approach, people should consume a diet that includes a variety of nutrient-dense, fibrous carbs, such as fruits and vegetables, alongside nutritious protein sources, and healthful fats.
How long can I maintain a keto diet safely?
There is a fair amount of research backing the potential benefits of the ketogenic diet, including weight loss blood sugar regulation. However, the majority of studies have only taken place over short periods of a few weeks or months.
Some studies show the benefits of following the ketogenic diet over more extended periods of up to 2 years. However, there is a lack of studies exploring the potential side effects of following a ketogenic diet for longer periods.
One recent cohort study that followed 432,179 adults over 25 years associated both high and low carbohydrate intake with a greater risk of mortality than moderate carbohydrate intake. Specifically, people who consumed more than 70% or less than 40% of calories from carbohydrates were at a higher risk of mortality.
While it is likely that you will lose weight when following the ketogenic diet correctly on a short-term basis, research suggests that it is probably not the healthiest diet to follow long-term.
If you want to try the ketogenic diet, it may be best to limit this dietary pattern to a few months, then transition back to a less restrictive diet that you can maintain long-term. No matter what diet you follow, remember to make sure you are consuming whole, nutritious foods.
Jillian Kubala, MS, RD Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.