What is a Fat Fast?
A fat fast is a short-term, restrictive version of the ketogenic diet, typically lasting two to five days. During this period, your daily calorie intake is limited to around 1,000–1,200 calories, with 80-90% coming from fat and minimal carbs and protein. This forces your body to produce ketones at an accelerated rate, pushing it into a deeper state of ketosis to burn fat for fuel. It is often used by keto dieters to overcome a weight-loss plateau or to quickly return to ketosis after a high-carb meal. Given its restrictive nature, it is not recommended for long-term use and should be approached with caution.
The Core Principles of Fat Fasting Foods
The fundamental goal of a fat fast is to keep carbohydrates and protein low enough to maximize ketone production. This means focusing on foods with a very high fat-to-calorie ratio. The food list is deliberately limited to prevent overconsumption and keep your appetite suppressed.
Acceptable High-Fat Foods
- Healthy Oils: Extra virgin olive oil, avocado oil, coconut oil, MCT oil, and macadamia nut oil are staples. They can be used in cooking, salad dressings, or added to coffee and tea.
- High-Fat Dairy: Full-fat options like cream cheese, heavy whipping cream, and high-fat cheeses such as brie are permitted in moderation. Many prefer to limit dairy, but small amounts are acceptable for some.
- Fatty Proteins: High-fat meat like bacon, fatty fish such as salmon and sardines, and whole eggs are allowed but must be portioned carefully to avoid too much protein. Egg yolks, in particular, are excellent due to their high fat content.
- Avocados and Olives: These are the primary high-fat, low-carb fruits that can be consumed. Avocados are versatile and can be mashed with mayonnaise for a quick salad or stuffed with egg.
- High-Fat Nuts and Nut Butters: Macadamia nuts and their butter are ideal because of their superior fat content and lower protein ratio compared to other nuts. Portion control is key with nuts, as calories can add up quickly.
- Non-Dairy Fats: Full-fat coconut milk and coconut cream are excellent for adding richness to beverages and recipes.
- Butter and Ghee: These are pure fats that can be used generously in cooking or added to coffee for an energy boost.
- Fat Bombs: These are small, bite-sized snacks made from a high concentration of fat sources like coconut oil, cocoa, and cream cheese. They are a popular way to get fat macros in and provide a feeling of satiety.
Beverages for Hydration and Flavor
Staying hydrated is crucial during a fat fast. Water, coffee, and tea are your go-to options. Adding a little heavy cream to your coffee can also contribute to your fat macro goals. Some individuals also consume bone broth for electrolytes, though some expert approaches suggest scaling back over time.
What to Avoid on a Fat Fast
The restricted nature of this diet means many foods are off-limits to prevent carb and protein intake from disrupting ketosis. Avoiding these foods is as important as consuming the right ones.
Foods and Drinks to Eliminate
- Carbohydrates: All grains, cereals, breads, pasta, and most fruits and starchy vegetables must be avoided. This includes legumes like beans and lentils.
- Low-Fat Products: Any dairy, meat, or fish that is low-fat or lean should be avoided, as it will increase protein relative to fat.
- Sugar and Sweeteners: Candies, sweets, cakes, and sweetened beverages like juice and soda are prohibited.
- Alcohol: This should be avoided due to its carb content and effect on metabolism.
Sample Fat Fast Meal Plan
A daily menu during a fat fast consists of four to five small meals of 200-250 calories each to stay within the recommended 1,000–1,200 calorie range.
Day 1
- Meal 1: Coffee with heavy whipping cream.
- Meal 2: A quarter avocado with macadamia nut butter.
- Meal 3: Egg salad made with full-fat mayonnaise and served in lettuce wraps.
- Meal 4: A small portion of salmon mashed with mayo.
- Meal 5: A savory fat bomb, such as a bacon and cheese bite.
Day 2
- Meal 1: A few slices of bacon.
- Meal 2: Hard-boiled egg yolks with a tablespoon of mayonnaise.
- Meal 3: A small salad of leafy greens drizzled with olive oil and topped with olives.
- Meal 4: A savory pizza-style fat bomb.
- Meal 5: Cream cheese with a splash of sugar-free flavoring.
Fat Fasting vs. Standard Ketogenic Diet
The following comparison table highlights the key differences between a fat fast and a standard keto diet:
| Feature | Fat Fast | Standard Ketogenic Diet |
|---|---|---|
| Duration | Short-term (2–5 days) | Long-term and sustainable |
| Calorie Intake | Restricted to 1,000–1,200 calories | Varies, can be higher, but still often in a deficit |
| Macronutrient Ratio | Very high fat (80-90%), very low protein and carbs | High fat (75%), moderate protein (20%), and very low carb (5%) |
| Purpose | Breaking weight-loss plateaus, accelerating ketosis | Sustainable weight loss, improved metabolic health |
| Food Variety | Highly restrictive, repetitive food options | Wide range of approved low-carb foods, more variety |
| Safety | Not recommended for extended periods due to nutrient limitations | Can be safely maintained for long periods under proper guidance |
How to Succeed at Fat Fasting
- Stay Hydrated: Drink plenty of water throughout the day to support your body's metabolic processes and flush out toxins.
- Prioritize Electolytes: Consider supplementing with sodium, potassium, and magnesium, especially if you experience fatigue or headaches, as these minerals are often depleted on very low-carb diets.
- Listen to Your Body: Don't force yourself to continue if you feel unwell. Fat fasting is a temporary tool, not a long-term solution.
- Plan Your Meals: The restrictive nature means planning is essential. Prepare your small, high-fat meals and snacks in advance to avoid making poor choices.
- Break the Fast Gently: When finished, reintroduce a wider variety of ketogenic foods slowly to avoid digestive distress. Jumping back to a high-carb diet can negate the fast's benefits.
Conclusion
Fat fasting is a highly restrictive, short-term dietary strategy designed to accelerate the body's entry into ketosis. By consuming a very high percentage of calories from fat while minimizing carbs and protein, you can effectively break through a weight-loss plateau or reset your metabolism. However, its brevity is key; this method is not a sustainable or nutritionally complete approach for the long term. Focusing on healthy high-fat foods, staying hydrated, and planning carefully are the foundations of a successful and safe fat fast. Remember to always consult a healthcare professional before starting any new diet, especially one as extreme as this.
Sources
"Feeling stuck on keto? Try a fat fast!" Dr. Simonds. 21 Sep 2021. https://simondsmetabolics.com/2021/09/21/feeling-stuck-on-keto-try-a-fat-fast/ "What Is Fat Fasting, and Is It Good for You?" Healthline. 29 Apr 2019. https://www.healthline.com/nutrition/keto-fat-fast "Fat Fasting - A Fasting 'Training Wheel'." The Fasting Method. 2019. https://www.thefastingmethod.com/wp-content/uploads/2024/06/Fat-Fasting.pdf "Keto Fat Fasting Techniques: Top Benefits, Side Effects, and More." Ruled.me. 30 Sep 2022. https://www.ruled.me/using-fat-fasting-technique/ "What to Eat After Fasting and What to Avoid to Reap the Benefits." BetterMe. 21 Dec 2024. https://betterme.world/articles/what-to-eat-after-fasting/
