The ketogenic diet (KD), characterized by its high-fat, moderate-protein, and very low-carbohydrate composition, has surged in popularity over the last decade, primarily due to its effectiveness in promoting short-term weight loss. While it has garnered attention for various potential health benefits, it's crucial to understand both its advantages and potential risks. This article delves into the keto diet, examining its mechanisms, benefits, and drawbacks, to provide a comprehensive understanding of this dietary approach.
What is the Keto Diet?
The keto diet is a high-fat, moderate protein, low-carbohydrate diet. A true ketogenic diet is different. Unlike other low-carb diets, which focus on protein, a keto plan centers on fat, which supplies as much as 90% of daily calories. It fundamentally alters how the body utilizes food for energy. Normally, the body relies on glucose, derived from carbohydrates, as its primary energy source. However, the keto diet restricts carbohydrates to 50 grams per day or less, forcing the body to switch to fat as its primary fuel source. This metabolic shift leads to a state called ketosis. The keto diet reduces your total carb intake to less than 50 grams a day. This is the equivalent of a cup of white rice. The keto diet excludes carb-rich foods like grains, beans, fruits and starchy vegetables.
Understanding Ketosis
Ketosis is a metabolic adaptation to allow the body to survive in a period of famine. Ketosis is a process that occurs when your body uses fat as its main fuel source. Normally, your body uses blood sugar (glucose) as its key energy source. When carbohydrate intake is drastically reduced, the body depletes its glycogen (stored glucose) reserves. As a result, the body breaks down fats into molecules called ketones. Ketones serve as an alternative fuel source. The fat your body uses to create ketones may come from your diet (nutritional ketosis), or it may come from your body’s fat stores. The ketones, or ketone bodies, become your body and brain’s main source of energy. This metabolic state is achieved by consuming a diet consisting of approximately 75% of calories from fat, 5% from carbohydrates (about 20-50 grams per day), and 15% from protein, compared to 20-35 percent normally. This metabolic state is achieved by consuming a diet consisting of approximately 75% of calories from fat, 5% from carbohydrates (about 20-50 grams per day), and 15% from protein. It takes about 72 hours for ketosis to kick in.
Food Choices on the Keto Diet
People following the keto diet should be eating foods like fatty fish, eggs, dairy, meat, butter, oils, nuts, seeds and low-carb vegetables. Because the keto diet has such a high fat requirement, followers must eat fat at each meal. In a daily 2,000-calorie diet, that might look like 165 grams of fat, 40 grams of carbs, and 75 grams of protein. Some healthy unsaturated fats are allowed on the keto diet - like nuts (almonds, walnuts), seeds, avocados, tofu, and olive oil. Vegetables (also rich in carbs) are restricted to leafy greens (such as kale, Swiss chard, spinach), cauliflower, broccoli, Brussels sprouts, asparagus, bell peppers, onions, garlic, mushrooms, cucumber, celery, and summer squashes. "Fat bombs" like unsweetened chocolate or coconut oil can help people reach their daily goals for fat intake.
Potential Benefits of the Keto Diet
The ketogenic diet has been explored for various potential health benefits, including:
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Weight Loss
The keto diet has been shown to effectively lead to weight loss, reduction in hyperinsulinemia, and improvement in insulin sensitivity. One of the biggest benefits of ketosis may be weight loss. The process can help you feel less hungry, which may lead to eating less food. It can help you lose belly fat (visceral fat) while maintaining a lean mass. 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.
Blood Sugar Management in Type 2 Diabetes
Low carb diets have been a mainstay of diabetes management, and they were recommended well before injectable insulin became available. The keto diet can help people with Type 2 diabetes lose weight and manage their blood sugar levels. 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.
Management of Refractory Seizures in Pediatric Patients
The concept of KD was initially developed in 1921 by Dr. Russel Wilder for the management of refractory seizures in pediatric patients. 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.
Polycystic Ovary Syndrome (PCOS)
KD has been postulated to positively impact women diagnosed with polycystic ovarian 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. Participants adhered to a six-month period of strict KD consisting of less than 20 g of CHO per day with unlimited consumption of animal-based foods. 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.
Potential Benefits for Other Neurologic Conditions
Research has shown the keto diet may help improve neurological conditions such as Alzheimer’s disease, autism and brain cancers such as glioblastoma.
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Cardiovascular Disease
The keto diet may lower your risk of developing cardiovascular disease by lowering your blood pressure, improving your HDL (“good”) cholesterol levels and lowering your triglycerides.
Metabolic Syndrome
The keto diet may reduce your risk of developing metabolic syndrome, which is associated with your risk of heart disease.
Increased Focus and Energy
Ketosis has also been shown to increase your focus and energy. The keto diet delivers your body’s energy needs in a way that reduces inflammation. Research suggests your brain works more efficiently on ketones than on glucose.
May ‘Starve’ Cancer Cells of Energy
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.
Potential Risks and Side Effects of the Keto Diet
While the keto diet offers potential benefits, it's essential to be aware of its potential risks and side effects:
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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. People report feeling foggy, irritable, nauseous and tired.
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.
Potential Negative Impacts on Heart Health
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 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.
Kidney Problems
The kidneys help metabolize protein, and McManus says the keto diet may overload them. 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.
The "Keto Flu"
One of the signs of ketosis may include “keto flu,” which includes symptoms such as upset stomach, headache and fatigue. Common short-term side effects resulting from the initiation of KD have been referred to as “keto flu,” which encompasses symptoms including fatigue, headache, dizziness, nausea, vomiting, constipation, and low exercise tolerance. Symptoms typically resolve after a few days to weeks as the body adjusts to the low CHO, ketogenic state.
Long-Term Side Effects
Long-term side effects include hepatic steatosis, kidney stones, hypoproteinemia, and vitamin deficiency.
Not Sustainable
Strict diets like keto could also cause social isolation or disordered eating. The keto diet is quite restrictive and hard to sustain long-term, making it not the best choice for lifelong weight management. The best diet for weight management is one that can be maintained long-term.
Low Blood Pressure and Blood Sugar
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.
Social Isolation or Disordered Eating
Strict diets like keto could also cause social isolation or disordered eating.
Cost
Keto-compliant foods like red meats and nuts can be costly.
Important Considerations
- Individual Variability: “There’s not one diet that’s good for everyone,” Kleinman says. No one diet fits all, and what works for one person may not work for another.
- Long-Term Compliance: While the benefits of following KD have been extensively reported, long-term compliance with KD is a limiting factor.
- Quality of Food: As reported by Seidelmann et al. in a prospective cohort study and meta-analysis, it is not only a matter of CHO restriction but also the quality of food ingested. Further analysis of the results demonstrated that mortality was worse when fat and protein sources were animal-derived instead of plant-derived.
- Work with a Registered Dietitian: 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.
Alternative Approaches
Reduction vs. A better choice when thinking about weight management would be to reduce the type of carbohydrates you eat rather than following the strict restriction of the keto diet. The priority should be to reduce simple carbohydrates and include more complex carbohydrates. Complex carbohydrates are high in nutrients and fiber that increase fullness, which can help with weight control. Don't restrict carbohydrates - rather, reduce them by choosing more complex carbs. This approach may be more sustainable. 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.