The ketogenic (keto) diet, characterized by its high-fat, moderate-protein, and very low-carbohydrate composition, has surged in popularity as a weight-loss strategy. Though it may seem newer to your newsfeed, the ketogenic diet has been around since the 1920s. The keto diet is all about cutting carbs and eating more fat, similar to the Atkins diet from the 1970s. It involves drastically reducing carbohydrate intake, typically to less than 50 grams per day, and increasing fat consumption to as much as 90% of daily calories. This metabolic shift forces the body to use fat as its primary fuel source, leading to the production of ketones. While the keto diet has demonstrated potential benefits for weight loss, blood sugar management, and certain neurological conditions, it also carries potential risks and challenges that warrant careful consideration.
Understanding the Keto Diet
The primary objective of the keto diet is to induce a metabolic state called ketosis. Normally, the body relies on glucose, derived from carbohydrates, as its main energy source. However, when carbohydrate intake is severely restricted, the body depletes its glucose stores and begins to break down fat into molecules called ketones in the liver due to low insulin levels. These ketones then serve as an alternative fuel source for the body, including the brain.
The standard ketogenic diet typically consists of:
- 70-80% of calories from fat
- 10-20% of calories from protein
- 5-10% of calories from carbohydrates
This translates to a daily intake of less than 50 grams of carbohydrates, which excludes carb-rich foods like grains, beans, fruits, and starchy vegetables and including low-carb, non-starchy vegetables and small amounts of leafy greens. The keto diet excludes carb-rich foods like grains, beans, fruits and starchy vegetables. For context, 50 grams of carbohydrates is roughly equivalent to a cup of white rice.
Potential Benefits of the Keto Diet
Weight Loss
One of the primary reasons for the keto diet's popularity is its potential for weight loss. There has been anecdotal evidence of people losing weight on the ketogenic diet. People also report feeling less hungry than on other types of restricted diets. The keto diet allows many people to eat the types of high-fat foods that they enjoy, such as red meats, fatty fish, nuts, cheese and butter, while still losing weight.
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Several factors contribute to this effect:
- Reduced Appetite: Studies have found that individuals on a keto diet report less hunger and desire to eat. 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.
- Water Weight Loss: 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.
- Fat Burning: 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.
However, it's important to note that most research on keto for weight loss has been conducted on individuals with obesity. Therefore, the same results may not be observed in those seeking to lose a smaller amount of weight.
Blood Sugar Management in Type 2 Diabetes
The keto diet has shown promise in managing blood sugar levels, particularly in individuals with type 2 diabetes. Low carb diets have been a mainstay of diabetes management, and they were recommended well before injectable insulin became available. 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.
By restricting carbohydrate intake, the keto diet helps stabilize blood sugar levels and reduce the need for medication. 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.
In an outpatient clinic study by Yancy et al., overweight patients diagnosed with type 2 diabetes were made to follow a VLCKD throughout 16 weeks with the primary outcome measure of monitoring blood glucose control through HbA1c levels. At the end of the 16-week timeframe, HbA1c decreased from 7.5 ±1.4% to 6.3 ±1.0% (p<0.001).
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Epilepsy
The keto diet has a long history of use in treating epilepsy, particularly in children. The keto diet helps reduce seizures in children with epilepsy. Healthcare providers often put children with epilepsy on the keto diet to reduce or even prevent seizures by altering the “excitability” part of their brain. While the exact mechanisms are not fully understood, it is believed that ketones have a stabilizing effect on brain activity, reducing the frequency of seizures.
Other Potential Benefits
Emerging research suggests that the keto diet may offer benefits for other conditions, including:
- Neurological Disorders: The keto diet is being studied for reducing symptoms for patients with progressive neurological disorders like Parkinson’s disease. Research has shown the keto diet may help improve neurological conditions such as Alzheimer’s disease, autism and brain cancers such as glioblastoma.
- Cancer: 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.
- Polycystic Ovary Syndrome (PCOS): A study by Mavropoulos et al. implemented KD for women between the ages of 18-45 years diagnosed with PCOS, with a BMI greater than 27 kg/m2, and no other serious medical conditions. After 24 weeks, the results of the study (pre- and post-design) showed a statistically significant decrease in fasting serum insulin, LH-to-FSH ratio, and free testosterone.
However, it's important to note that scientific research has not confirmed benefits for these patients, Dr. Ring says, and more research is needed before it can be widely recommended.
Potential Risks and Side Effects of the Keto Diet
Despite its potential benefits, the keto diet is not without risks and side effects.
Nutrient 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. The ketogenic diet can be effective for weight loss when used in a short time period followed by the adoption of healthier eating habits.
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Without careful planning, Dr. Ring explains that because the keto diet is so restricted, you’re not receiving the nutrients - vitamins, minerals, fibers - that you get from fresh fruits, legumes, vegetables and whole grains.
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.
Heart Health Concerns
The high-fat nature of the diet could also have negative impacts on heart health. The American Heart Association recommends limiting saturated fat intake to less than 6%. “In practice, many people eat high amounts of saturated fats, which could increase your risk of heart disease,” says Dr. Cheema. “You may be eating a lot of fatty meat thinking it’s a good thing for you because it's high in fat. This can dramatically alter your lipid profile. While high-fat diets can elevate LDL (“bad”) cholesterol, the type of saturated fat matters. The bottom line is that having more fats in your diet can lead to higher cholesterol. “We know that higher cholesterol tends to increase your chances of heart attacks and strokes,” says Dr. Cheema.
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.
Kidney Problems
The keto diet may not be appropriate for everyone, specifically people with kidney disease. “Although more research is needed in that area, there is some suggestion that it can make kidney disease worse over time,” says Dr. Some people also experience dehydration on the keto diet because they’re eliminating glycogen, which holds water, from the bloodstream.
Psychological Distress
When you micromanage your food intake by tracking how much you eat, it disconnects you from what your body is asking for. You start using outside numbers to determine what to eat instead of listening to your body. “Being intuitive and understanding what your body needs is essential for proper nourishment,” says Merneedi. Monitoring food so closely can lead to psychological distress, such as shame and binge eating.
Other Side Effects
The keto diet can cause your blood pressure to drop in the short term due to a reduction in blood volume and changes in your fluid balance. Symptoms of low blood pressure include dizziness, lightheadedness or fainting, especially when standing up quickly. Following a keto diet can also cause your blood sugar to drop, which can be dangerous for people living with diabetes. Common symptoms of low blood sugar include weakness or shaking, sweating, a fast heartbeat and dizziness. People report feeling foggy, irritable, nauseous and tired.
Long-Term Sustainability and Considerations
Because of the stringent food restrictions, many find the keto diet hard to stick to. “The ketogenic diet can be effective for weight loss when used in a short time period followed by the adoption of healthier eating habits,” says Baljash Singh Cheema, MD, a cardiologist at Northwestern Medicine Bluhm Cardiovascular Institute. “However, we know in studies of these types of diets that once people stop following that diet, they regain at least half of the weight that they lost. Ketosis is difficult to achieve because it’s like a light switch: either on or off. Individuals who consistently track food intake are more likely to remain in ketosis.
For long-term weight loss, Dr. Ring, Dr. Intermittent fasting is an approach that allows you to receive the benefits of ketosis while still eating a varied and balanced diet, says Dr. Ring. By cycling between periods of eating and fasting, your body enters “mild ketosis” during the fasting phase. “Unlike the keto diet, which requires strict food restrictions, intermittent fasting lets you enjoy a variety of nutrient-dense foods, such as fruits, vegetables, whole grains and legumes, during eating windows,” Dr. Ring explains.