Keto Diet: How Does It Work?

The ketogenic diet, or keto diet, is a low-carb, high-fat eating plan that has been used for centuries to treat specific medical conditions. In the 19th century, it was used to help control diabetes, and in 1920, it was introduced as an effective treatment for epilepsy in children. The keto diet has also been tested and used in closely monitored settings for cancer, diabetes, polycystic ovary syndrome, and Alzheimer's disease.

The keto diet is distinctive for its exceptionally high-fat content, typically 70% to 80%, though with only a moderate intake of protein. The premise of the keto diet for weight loss is that if you deprive the body of glucose, an alternative fuel called ketones is produced from stored fat. The brain demands a steady supply of glucose, about 120 grams daily, because it cannot store glucose. During fasting or when very little carbohydrate is eaten, the body first pulls stored glucose from the liver and temporarily breaks down muscle to release glucose. If this continues for 3-4 days and stored glucose is fully depleted, blood levels of insulin decrease, and the body begins to use fat as its primary fuel. The liver produces ketone bodies from fat, which can be used in the absence of glucose.

The keto diet is a low-carb, high-fat diet

On a keto diet, you need to be mindful of your protein consumption, as too much protein can be converted into glucose, slowing your transition into ketosis. It's also important to keep your fat consumption high, with fat making up a large part of every meal. In a 2,000-calorie diet, this could look like 165 grams of fat, 40 grams of carbs, and 75 grams of protein.

Some healthy unsaturated fats that are allowed on the keto diet include nuts (such as almonds and walnuts), seeds, avocados, tofu, and olive oil. However, the diet encourages the consumption of saturated fats from oils (palm and coconut), lard, butter, and cocoa butter.

When it comes to food choices on the keto diet, animal proteins like meat, fish, and eggs are recommended. Fatty fish like salmon, trout, tuna, and mackerel are especially good choices due to their high omega-3 fat content. Cheese is also a popular choice, as it is low in carbs and high in fat.

Vegetables are an important part of the keto diet, but they need to be low-carb options like leafy greens (kale, Swiss chard, spinach), broccoli, asparagus, bell peppers, and summer squashes. Fruit is restricted due to its high carb content, but small portions of berries are usually allowed.

The keto diet has become popular due to its potential benefits for weight loss and blood sugar control. Additionally, early evidence suggests that this low-carb, high-fat diet may help treat certain cancers, Alzheimer's disease, and other health conditions. However, it's important to note that the keto diet is associated with several risks, including high levels of saturated fat, nutrient deficiency, liver and kidney problems, and constipation. Therefore, it's crucial to consult a doctor and a registered dietitian before starting this diet.

It changes the way your body uses fuel

The keto diet is a low-carb, high-fat diet that changes the way your body uses fuel. Typically, your body uses blood sugar (glucose) as its key energy source. This glucose is derived from eating carbohydrates (carbs) such as starches and sugars. On the keto diet, however, 70-80% of your calories come from fat, 10-20% from protein, and just 5-10% from carbohydrates.

When your body doesn't have enough carbs to burn for energy, it burns fat instead. This process is called ketosis, and it typically takes a few days to enter this state. During ketosis, your body breaks down fat and produces a compound called ketones, which become your body and brain's main source of energy.

Ketosis can be challenging to achieve, and it's important to monitor your intake of carbs, fat, and protein. Eating too much protein can interfere with ketosis. To achieve ketosis, you'll need to stay under 50 grams of carbohydrates per day. That's about three slices of bread, two bananas, or one cup of pasta.

The keto diet is an effective way to lose weight and has been linked to other health benefits, such as increased energy and improved neurological conditions. However, it's important to note that the keto diet is associated with high levels of saturated fat, which can increase the risk of heart disease. Therefore, it's crucial to consult a doctor and a registered dietitian before attempting this diet.

It can be challenging to maintain

Maintaining a keto diet can be challenging for several reasons. Firstly, it requires a significant reduction in carbohydrate intake, limiting consumption to around 20-50 grams per day. This means cutting out grains, legumes, fruits, starchy vegetables, and sugar, which can be difficult to adjust to and may lead to cravings. Secondly, the keto diet has a high-fat requirement, with fat comprising up to 90% of daily calories. This means that followers must eat fat at every meal, which can be challenging for those used to a standard diet.

One challenge of staying in ketosis is avoiding too much protein. While protein is part of the keto diet, eating too much can interfere with ketosis. It's important to moderate protein intake and choose lean protein sources over those high in saturated fat, such as beef, pork, and bacon.

Another challenge is the potential for nutrient deficiencies. The keto diet restricts many nutrient-rich foods, such as fruits, vegetables, and grains. As a result, individuals on the keto diet may be at risk for deficiencies in micronutrients like selenium, magnesium, phosphorus, and vitamins B and C.

The keto diet can also be challenging to maintain due to its restrictive nature. It requires eliminating many common foods, including sugary treats, starchy comfort foods, and even some fruits and vegetables. This restriction can make it difficult to stick to the diet, especially when dining out or attending social gatherings. Additionally, the keto diet may lead to initial side effects, often referred to as the "keto flu," which can include digestive issues, decreased energy, and mental fog. These side effects usually subside within a few days but can be off-putting for those new to the diet.

Furthermore, the keto diet may not be suitable for everyone. It is recommended that individuals with existing liver conditions avoid this diet, as the high-fat content can worsen liver problems. Similarly, the diet may overload the kidneys, which are responsible for metabolizing protein. Therefore, it is crucial to consult a doctor and a registered dietitian before starting the keto diet to ensure it is safe and appropriate for your individual needs.

It has been linked to treating chronic illnesses

The ketogenic diet has been linked to treating chronic illnesses. It has been used to treat epilepsy for almost 100 years, especially in children with drug-resistant epilepsy. The diet is thought to reduce seizures in epilepsy patients by forcing the body to use a different type of fuel. Instead of relying on sugar (glucose) from carbohydrates, the keto diet relies on ketone bodies, a type of fuel that the liver produces from stored fat.

The keto diet has also been linked to reducing the risk of other chronic illnesses. These include metabolic syndrome, type 2 diabetes, cancer, polycystic ovary syndrome, Alzheimer's disease, multiple sclerosis, traumatic brain injury, nonalcoholic fatty liver disease, and migraine headaches.

For metabolic syndrome, the keto diet may improve cholesterol values, as well as reduce blood sugar and blood pressure. In a controlled 12-week study, people with metabolic syndrome on a calorie-restricted ketogenic diet lost body fat and experienced a reduction in triglycerides and other health markers.

For type 2 diabetes, the keto diet has been shown to improve blood sugar control and, in some cases, lead to a reduction in medication. Dozens of controlled studies show that a very low-carb diet helps control blood sugar and may provide other health benefits.

For cancer, the keto diet may be used in conjunction with traditional treatments such as chemotherapy, radiation, and surgery. The diet may help slow tumour growth by lowering blood sugar and insulin levels. Animal studies show that ketogenic diets may reduce the progression of several types of cancer, and some experts believe the diet may be particularly beneficial for brain cancer.

For polycystic ovary syndrome (PCOS), a ketogenic diet may lead to weight loss, a reduction in insulin levels, and an improvement in reproductive hormone function. In a 6-month study of eleven women with PCOS following a ketogenic diet, weight loss averaged 12%, fasting insulin declined by 54%, and reproductive hormone levels improved.

For Alzheimer's disease, the keto diet may improve several symptoms. Animal studies show that a ketogenic diet improves balance and coordination. Human studies suggest that supplementing with ketone esters or MCT oil may also be beneficial.

For multiple sclerosis (MS), the keto diet may suppress inflammatory markers, leading to improvements in memory, learning, and physical function. A 2015 review discussed the potential of ketogenic diets to assist with energy production and cell repair in MS patients.

For traumatic brain injury (TBI), animal studies suggest that starting a ketogenic diet immediately after injury can help reduce brain swelling, increase motor function, and improve recovery. However, there are currently no quality human studies on this.

For nonalcoholic fatty liver disease (NAFLD), the keto diet may be effective at reducing liver fat and other health markers. In a small study, 14 obese men with metabolic syndrome and NAFLD who followed a ketogenic diet for 12 weeks had significant decreases in weight, blood pressure, and liver enzymes.

For migraine headaches, some studies suggest that migraine frequency and severity may improve for people following a ketogenic diet. One observational study reported a reduction in migraine frequency and pain medication use in people following a ketogenic diet for one month.

While the keto diet has been linked to treating chronic illnesses, it is important to note that it also has risks and side effects. It is a restrictive diet that can be challenging to follow, and it may not be suitable for everyone. It is always recommended to speak to a doctor or qualified healthcare provider before starting any new diet.

It can have adverse side effects

The keto diet has been linked to a number of adverse side effects, which can be serious enough to warrant speaking to a doctor before starting the diet.

One of the most well-known side effects of the keto diet is "keto flu". This is a collection of flu-like symptoms, including headaches, dizziness, fatigue, nausea, and constipation, which can last for several weeks. This is caused by dehydration and electrolyte imbalances as the body adjusts to ketosis.

The keto diet can also lead to digestive issues and constipation, due to the restriction of fibrous foods. This can also negatively impact the gut, as fibre feeds the beneficial bacteria in the gut.

The diet may also lead to nutrient deficiencies, as it restricts nutrient-dense fruits, whole grains, and legumes. Studies suggest that the keto diet may not provide enough calcium, vitamin D, magnesium, and phosphorus. Over time, this can lead to nutrient deficiencies.

There are also more serious health risks associated with the keto diet. It may cause liver problems, as the organ has to metabolise so much fat. It may also cause kidney problems, as the high intake of animal foods can cause your blood and urine to become more acidic, leading to an increased risk of kidney stones.

Finally, the keto diet has been linked to impaired bone health, with several studies in animals linking the diet to decreased bone strength and bone mineral density loss.

Due to these risks, it is important to speak to a doctor before starting the keto diet, especially for those with kidney disease, diabetes, heart or bone ailments, or other medical conditions.

Frequently asked questions