Starting the ketogenic diet can feel overwhelming. With so much conflicting information online, it’s easy to get lost. But the core principle of keto is incredibly simple: we are trying to switch your body’s primary fuel source from burning sugar (glucose) to burning fat (ketones).

The key to this switch is controlling a single hormone: insulin. When insulin is low, your body burns fat. When it’s high, it burns sugar.

This guide will give you the two simple, powerful rules for doing keto correctly and healthily, focusing on what to eat and when to eat to keep insulin low and turn your body into a fat-burning machine.

The Two Golden Rules of Healthy Keto:
  • Rule #1: What to Eat - Eat very low-carb foods, moderate protein, and high-quality fats.
  • Rule #2: When to Eat - Eat less frequently (intermittent fasting) to minimize insulin spikes.

Rule #1: What to Eat on a Healthy Keto Diet

This is the foundation. Your meals should be structured around these three macronutrient groups, in this order of priority.

Part 1: Vegetables (At Least 7 Cups a Day)

This is the most overlooked part of a healthy keto diet. You should aim to consume a large volume of low-carbohydrate vegetables.

  • Why? Vegetables provide essential fiber for your gut microbes, as well as crucial nutrients like potassium and magnesium that can be lost during the initial phase of keto.
  • What to Eat: Big salads, broccoli, cauliflower, cabbage, kale, bell peppers, asparagus, and brussels sprouts.
  • Pro Tip: Eat your vegetables first. You’re more likely to consume the full 7+ cups if you eat your salad before the more filling protein and fat.

A large, vibrant salad in a white bowl, filled with mixed greens, avocado, and bell peppers.

Part 2: Moderate Protein (The Size of Your Palm)

Keto is not a high-protein diet like Atkins. The goal is a moderate amount of protein with each meal.

  • How Much? A simple guide is a portion the size of the palm of your hand, roughly 3 to 6 ounces depending on your size and activity level.
  • What to Eat: Fatty fish (like salmon), chicken (with skin), red meat, eggs, and cheese.
  • Crucial Point: Choose protein sources with a higher fat content. Lean protein, especially protein powders like whey, can spike insulin more than fattier cuts of meat. The fat helps keep you full and your insulin levels stable.

Part 3: High-Quality Fats (For Satiety and Fuel)

You are on a higher-fat diet, but the quality of that fat is critical.

  • What to Eat: The fat that naturally comes with your protein (e.g., in salmon or steak) is a great start. You can add more healthy fats like:
    • Avocado
    • Olive oil (on salads)
    • Butter (on vegetables)
    • Coconut oil or MCT oil
    • Nuts and nut butters (in moderation, and check for added sugar).
  • Fats to AVOID: Highly inflammatory seed oils like soy, corn, canola, and cottonseed oil. These are often found in processed foods and salad dressings, so start reading labels!

A beautifully plated keto meal of grilled salmon, sliced avocado, and asparagus.

Rule #2: When to Eat (Intermittent Fasting)

Eating less frequently is just as important as what you eat. Every time you eat, you spike insulin. By reducing your eating frequency, you give your body long periods where insulin is low, allowing it to burn fat.

The 3 Rules of Intermittent Fasting:

  1. Don’t Eat if You’re Not Truly Hungry. Learn the difference between true hunger (feeling weak, irritable) and habitual snacking or boredom. You don’t have to be “full” all the time.
  2. Skip Breakfast. The easiest way to start is to push your first meal of the day to noon. A coffee with a tablespoon of butter or MCT oil (a “bulletproof coffee”) can help you feel full and mentally sharp in the morning, as MCT oil provides a direct source of ketones.
  3. No Snacking. This is non-negotiable. Eating between meals, even a small keto-friendly snack, will spike your insulin and make you hungrier. If you feel the need to snack, it means you didn’t eat enough fat at your last meal. Add more fat to your main meals so you can comfortably go from one to the next.

A Sample Eating Schedule

A great starting point for beginners is an 18/6 schedule: * 18 hours of fasting. * 6-hour eating window.

For example: * First Meal: 12:00 PM (Noon) * Second Meal: 6:00 PM * No food before noon or after 6:00 PM.

A minimalist infographic of a clock showing an 18-hour fasting window and a 6-hour eating window.

By combining this powerful eating schedule with the right food choices, you create the optimal environment for lowering insulin, switching into a fat-burning state (ketosis), and achieving your health goals.