Biochemical Impact of the Keto Diet: Low Carb, High Fat

The Ketogenic Diet (often called the keto diet) is a high-fat, moderate-protein, and very low-carbohydrate diet designed to shift the body’s metabolism from relying on glucose (carbohydrates) as the primary source of energy to burning fat and producing ketones as an alternative fuel source. This metabolic state is known as ketosis.

Macronutrient Breakdown:

Carbohydrates: 5-10% of total daily calories (usually under 50 grams per day).

Fat: 70-80% of total daily calories.

Protein: 15-20% of total daily calories.

Mechanism of Action:

When carbohydrate intake is drastically reduced, the body is deprived of its usual source of glucose for energy. As a result, the liver starts converting fatty acids into ketones (acetoacetate, beta-hydroxybutyrate, and acetone), which can be used by the brain, muscles, and other tissues as an energy source. This process is called ketogenesis.

Types of Ketogenic Diets:

1. Standard Ketogenic Diet (SKD):
   • The most common form of the keto diet with high fat, moderate protein, and very low carbohydrate intake.
2. Cyclical Ketogenic Diet (CKD):
   • Involves periods of higher carbohydrate intake, such as 5 days of strict keto followed by 2 high-carb days (refeeding days).
3. Targeted Ketogenic Diet (TKD):
   • Allows additional carbohydrate intake around workouts to provide extra fuel for exercise.
4. High-Protein Ketogenic Diet:
   • Similar to the standard keto diet but with a higher protein intake, typically around 35% protein, 60% fat, and 5% carbohydrates.

Benefits of the Ketogenic Diet:

1. Weight Loss:
   • The keto diet is effective for short-term and long-term weight loss. By reducing insulin levels (the hormone that stores fat) and increasing fat oxidation, the body becomes more efficient at burning fat for energy.
   • Appetite suppression may occur due to the high-fat content and ketones’ effect on hunger-regulating hormones like ghrelin and leptin.
2. Improved Blood Sugar and Insulin Sensitivity:
   • The keto diet can lower blood glucose levels and improve insulin sensitivity, making it particularly beneficial for individuals with type 2 diabetes or insulin resistance.
3. Management of Epilepsy:
   • The ketogenic diet has been used for decades as a treatment for drug-resistant epilepsy, particularly in children. The exact mechanism is unclear, but ketones have been shown to reduce seizure frequency.
4. Potential Cardiovascular Benefits:
   • Some studies suggest the keto diet can improve heart health by lowering triglycerides, increasing HDL cholesterol (the “good” cholesterol), and reducing LDL particle size, although the long-term effects are still being studied.
5. Mental Clarity and Focus:
   • Ketones provide a steady supply of energy to the brain, which may improve cognitive function, mental clarity, and focus in some individuals.
6. Improvement in Neurological Disorders:
   • Emerging research suggests the keto diet may be beneficial for neurodegenerative diseases like Alzheimer’s disease and Parkinson’s disease, though more studies are needed to confirm these benefits.
7. Polycystic Ovary Syndrome (PCOS):
   • The keto diet may help women with PCOS by reducing insulin resistance, promoting weight loss, and improving hormonal balance.

Risks and Side Effects:

1. Keto Flu:
   • In the first few days to weeks of starting the keto diet, individuals may experience symptoms collectively known as the “keto flu.” Symptoms include fatigue, headache, dizziness, nausea, irritability, and brain fog. These symptoms are usually temporary and due to the body adjusting to ketosis and the loss of electrolytes.
2. Nutrient Deficiencies:
   • The diet restricts many foods (like fruits, vegetables, and whole grains), which may lead to deficiencies in vitamins (C, A, K), minerals (magnesium, potassium), and fiber unless carefully planned.
3. Constipation:
   • Due to the low fiber content from reduced intake of fruits, vegetables, and whole grains, constipation is a common side effect.
4. Increased Cholesterol and Heart Disease Risk (in some individuals):
   • While the keto diet may improve cholesterol markers in many individuals, it can raise LDL cholesterol in others, potentially increasing the risk of heart disease.
5. Kidney Stones:
   • Increased fat metabolism and reduced hydration may contribute to the development of kidney stones, particularly in individuals predisposed to kidney problems.
6. Liver Issues:
   • The liver has to work harder to produce ketones, which may exacerbate pre-existing liver conditions.
7. Loss of Muscle Mass:
   • In some cases, the keto diet may lead to muscle loss, especially if protein intake is insufficient or the diet is followed for extended periods without strength training.
8. Ketoacidosis (in rare cases):
   • Although this is more common in people with type 1 diabetes, individuals with type 2 diabetes may also experience diabetic ketoacidosis (a dangerous buildup of ketones) if insulin levels become extremely low.

Foods to Eat on the Keto Diet:

• Healthy Fats: Avocados, olive oil, coconut oil, nuts, seeds, and butter.
• Protein Sources: Meat (beef, pork, chicken), fatty fish (salmon, mackerel), eggs, and dairy (cheese, full-fat yogurt).
• Low-Carb Vegetables: Leafy greens, broccoli, cauliflower, zucchini, and peppers.
• Beverages: Water, coffee, tea (unsweetened), and bone broth.

Foods to Avoid on the Keto Diet:

• Sugary Foods: Soft drinks, candy, cakes, ice cream, and fruit juices.
• Grains and Starches: Bread, pasta, rice, potatoes, and oats.
• High-Carb Fruits: Most fruits, particularly bananas, apples, oranges, and grapes.
• Legumes: Beans, lentils, chickpeas, and peas.
• Processed Foods: Packaged snacks, sugary foods, and trans fats.

Ketogenic Diet and Weight Loss:

• Ketosis and Fat Burning: The ketogenic diet facilitates weight loss primarily by inducing ketosis, where fat stores are broken down into fatty acids and then converted into ketones for energy. The low-carbohydrate intake reduces insulin levels, promoting fat breakdown.
• Appetite Suppression: The keto diet has been found to reduce hunger, likely due to the satiating effects of fat and protein, along with the appetite-suppressing properties of ketones.

Who Should Avoid the Keto Diet:

• Individuals with pancreatic or liver disease: These organs are heavily involved in fat metabolism and ketone production, so the keto diet may exacerbate existing conditions.
• Individuals with eating disorders: Restrictive diets may trigger unhealthy behaviors.
• Pregnant or breastfeeding women: The long-term effects of the keto diet on fetal and infant development are not well understood.
• Individuals with type 1 diabetes: These individuals are at higher risk of developing diabetic ketoacidosis, which can be life-threatening.

Summary Table: Ketogenic Diet Pros and Cons

About the Author
Dr. Akif Ahamad Baig is a Consultant Interventional Cardiologist at Aster Ramesh Hospital in Guntur. He completed his MBBS at Siddhartha Medical College (2016), DNB in General Medicine from P.D. Hinduja Hospital (2020), and DM in Cardiology at Guntur Medical College (2023). Known for his expertise in complex coronary interventions, pacemaker implantation, and IVC filter placement, Dr. Baig is also a lifetime member of the Society of Cardiovascular Angiography and Interventions. He has several publications to his name and was recognized among the top 10 for the A.V. Gandhi National Award for Cardiology Thesis.