The Ketogenic (Keto) Diet: A Guide by a Registered Dietitian

The ketogenic, or “keto,” diet is a low-carb, high-fat dietary approach designed to shift the body’s metabolism from burning carbohydrates to burning fats as its primary energy source. By significantly reducing carbohydrate intake, the keto diet encourages the production of ketones—energy molecules derived from fat—which can help with weight loss, energy levels, and managing certain health conditions. Originally developed as a treatment for epilepsy, the keto diet has gained popularity for its benefits in weight management and metabolic health.

What Is the Keto Diet?

At its core, the keto diet involves a high-fat, moderate-protein, and low-carbohydrate structure. Typically, this translates to around 70-75% of daily calories coming from fats, 20-25% from proteins, and only 5-10% from carbohydrates. This macronutrient distribution is designed to induce a state of “ketosis,” where the liver produces ketones from stored fat to fuel the body, especially the brain. Unlike many diets, the keto approach can be quite restrictive and often requires a more intentional, lifestyle-based commitment to maintain ketosis.

Why Consider the Keto Diet?

The keto diet offers several benefits beyond weight loss. Here are some reasons why individuals consider this approach:

1. Metabolic Health: For people with insulin resistance, type 2 diabetes, or metabolic syndrome, the keto diet can help stabilize blood sugar levels and reduce insulin spikes. By cutting carbohydrates, the body has fewer fluctuations in blood sugar levels, which can support energy and mood stability.
2. Mental Clarity: Ketones are considered an efficient fuel source for the brain. Many individuals on the keto diet report enhanced mental clarity and sustained focus throughout the day. This effect is partially due to more stable blood sugar levels and the brain’s preferred use of ketones over glucose for energy.
3. Anti-Inflammatory Effects: Studies suggest that ketones may have anti-inflammatory properties. This can be particularly beneficial for those with chronic inflammatory conditions, such as arthritis or autoimmune diseases, where inflammation plays a role in symptom severity.

While keto offers these potential benefits, it’s essential to consider that, as with any diet, it’s not one-size-fits-all. Working with a registered dietitian can help you decide if keto aligns with your health goals and needs.

How the Keto Diet Works

The keto diet is divided into three main phases: adaptation, maintenance, and personalized adjustments. Understanding these stages can help you make the most of your keto journey and stay consistent with the diet’s requirements.

Phase 1: Adaptation

The adaptation phase, often called the “keto flu” phase, occurs within the first week or two of starting the keto diet. During this period, the body is adjusting to using fat as its primary fuel source instead of glucose. Common symptoms in this phase may include fatigue, dizziness, irritability, and cravings for carbs, as the body transitions to burning fat. Staying hydrated, increasing salt intake, and consuming electrolytes can help alleviate these temporary symptoms.

During the adaptation phase, focus on foods that are low in carbohydrates but high in healthy fats, such as:

• Fats: Avocado, olive oil, coconut oil, butter, and fatty fish like salmon.
• Proteins: Grass-fed beef, chicken thighs, eggs, and seafood.
• Low-Carb Vegetables: Leafy greens, zucchini, bell peppers, and cauliflower.

Phase 2: Maintenance

Once the body has adjusted to ketosis, the maintenance phase begins. This is the period where your body has adapted to burning fats as its primary fuel, allowing for sustained energy and reduced cravings. During this phase, you can continue to eat high-fat, moderate-protein, and low-carb meals while monitoring ketone levels to ensure your body remains in ketosis.

In the maintenance phase, you can experiment with a broader range of keto-friendly foods, including:

• High-Fiber Vegetables: Broccoli, asparagus, and Brussels sprouts.
• Dairy: Full-fat cheese, Greek yogurt (unsweetened), and cream, as tolerated.
• Nuts and Seeds: Almonds, walnuts, chia seeds, and flaxseeds (in moderation due to carbs).

Phase 3: Personalized Adjustments

As you progress, the keto diet can be tailored to meet individual needs. Some individuals may choose to follow a “cyclical keto” or “targeted keto” approach, where they periodically consume higher amounts of carbohydrates before returning to ketosis. This can be beneficial for athletes, those with specific fitness goals, or people looking for a more flexible approach.

Monitoring carbohydrate intake and understanding your personal tolerance for staying in ketosis can help you make adjustments without losing the benefits you’ve gained. Working with a dietitian can also ensure that you’re getting adequate nutrients and making sustainable changes that support your health.

Foods to Avoid and Include on the Keto Diet

Avoid:

• High-Carb Foods: Bread, pasta, rice, and most grains.
• Sugary Foods: Candy, soda, baked goods, and other high-sugar foods.
• Starchy Vegetables: Potatoes, sweet potatoes, corn, and parsnips.
• Fruits: Most fruits, especially bananas, apples, oranges, and grapes (opt for berries in moderation).

Include:

• Healthy Fats: Olive oil, avocado, butter, coconut oil.
• Proteins: Meat, poultry, fish, and eggs.
• Low-Carb Vegetables: Leafy greens, bell peppers, cauliflower, and zucchini.
• Nuts and Seeds: Almonds, chia seeds, and pumpkin seeds.
• Berries: Small portions of strawberries, blueberries, and raspberries.

Lifestyle Factors for Success on Keto

Following a keto diet requires more than just dietary changes. Lifestyle factors like hydration, stress management, and physical activity play a role in maintaining ketosis and supporting overall health. Staying hydrated, prioritizing adequate sleep, and incorporating exercise—particularly strength training—can enhance the effectiveness of the diet and help you achieve sustainable results. It’s also helpful to find ways to manage stress, as chronic stress can disrupt ketosis by increasing blood sugar levels.

The Science Behind Keto: Evidence of Effectiveness

The ketogenic diet has been widely studied for its benefits in various health conditions. Research shows that keto can be effective for weight loss and may improve insulin sensitivity, reduce inflammation, and promote cardiovascular health. In a 2018 study, participants following a keto diet lost significantly more weight and body fat than those on a low-fat diet. Another study found that keto improved blood sugar control and lipid profiles in people with type 2 diabetes, suggesting that it may help manage metabolic health markers.

Hallberg, Sarah J., et al. “Effectiveness and safety of a novel care model for the management of type 2 diabetes at one year: an open label, non-randomized, controlled study.” Diabetes Therapy, vol. 9, no. 2, 2018, pp. 583-612.

Bueno, N. B., et al. “Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials.” British Journal of Nutrition, vol. 110, no. 7, 2013, pp. 1178-1187.

Take-Home Messages:

• Metabolic Benefits: The keto diet can help with weight loss, reduce blood sugar, and improve metabolic health.
• Sustained Energy: Ketones provide a stable energy source, often leading to improved focus and mental clarity.
• Lifestyle Matters: Incorporating stress management, hydration, and exercise can enhance the keto experience.
• Personalization Is Key: Keto can be tailored to individual needs, whether through a strict or cyclical approach.

In summary, the keto diet offers a structured approach to weight loss and metabolic health, emphasizing a high-fat, low-carb regimen to promote ketosis. By focusing on nutrient-dense foods, lifestyle factors, and personalization, it provides a pathway for many individuals seeking improved health and wellness.