The Fast 800 is a flexible, science-backed approach to weight loss and improved metabolic health, founded by Dr. Michael Mosley. It incorporates intermittent fasting principles and a low-carb, Mediterranean-style diet. The key to understanding the carb allowance is to recognize that there isn't a single, fixed number, but rather different guidelines depending on which of the four main approaches you follow.
Understanding the Fast 800 Approaches
The program offers several pathways tailored to different goals and lifestyles. Each approach has a different emphasis on carbohydrate restriction.
The Very Fast 800
This is a rapid weight-loss phase designed for individuals with significant weight to lose.
- Calorie Target: Approximately 800 calories per day for up to 12 weeks.
- Carb Approach: A moderately low-carb, Mediterranean-style diet. This means while carbs are limited, they are not eliminated entirely. The focus is on complex carbohydrates from non-starchy vegetables and legumes rather than simple, processed ones. The carb allowance is higher than the Keto option, allowing for more dietary flexibility.
The Fast 800 Keto
For those seeking accelerated weight loss and a deep state of ketosis, this very low-carb option is available.
- Calorie Target: 800-1000 calories per day.
- Carb Approach: A very low-carb limit of under 50g per day. The online program's meal plans typically aim for even lower, around 20-30g or less. The program emphasizes a "Rule of 50," where daily carbs are kept under 50g and protein above 50g.
The New 5:2
This is a more sustainable, long-term intermittent fasting approach.
- Calorie Target: 800 calories on two non-consecutive 'fasting' days per week.
- Carb Approach: On fasting days, the meal plan follows a moderately low-carb, Mediterranean style, with a total carb intake of 50g or less, similar to the Very Fast 800. On the other five days, there is no calorie restriction, but a moderately low-carb, Mediterranean-style diet is encouraged.
The Way of Life
This is the final phase, designed for long-term weight maintenance and healthy eating habits.
- Calorie Target: No calorie counting.
- Carb Approach: A daily moderately low-carb, Mediterranean-style diet. The goal is to sustain the healthy eating patterns developed in earlier phases without strict carb counting.
Carb Limits Across Different Plans
While the Fast 800 promotes low-carb eating, the specific limits differ by plan. The key distinction is between the standard Very Fast 800/New 5:2 approach and the more restrictive Keto phase. The Keto phase pushes the body into ketosis faster by more severely limiting carbohydrate intake, whereas the other plans offer a more moderate reduction.
The "Rule of 50"
On the Fast 800 Keto plan, the "Rule of 50" is a simple guideline: keep carbs under 50g per day and protein above 50g. This balance helps ensure satiety while driving the body to burn fat for fuel. A typical ketogenic diet is often higher in fat, but the Fast 800 Keto is adapted to a lower-calorie, Mediterranean-style plan.
What Are "Good" Carbs on the Fast 800?
The Fast 800 is a low-carb diet, not a no-carb diet. It emphasizes replacing highly refined or starchy carbs with nutrient-dense, high-fiber options.
- Carbs to Embrace:
- Non-starchy vegetables: Leafy greens, broccoli, cauliflower, bell peppers.
- Fiber-rich foods: Legumes (in moderation), certain fruits (berries).
- Nuts and seeds: Excellent sources of fiber and healthy fats.
- Carbs to Avoid or Limit:
- Simple carbs: Sugary drinks, sweets, fruit juices.
- Starchy carbs: Potatoes, white rice, bread, pasta.
Comparison of Fast 800 Approaches
| Feature | Very Fast 800 | Fast 800 Keto | New 5:2 (Fasting Days) | New 5:2 (Non-Fasting Days) | Way of Life |
|---|---|---|---|---|---|
| Primary Goal | Rapid Weight Loss | Accelerated Weight Loss | Steady Weight Loss | Steady Weight Loss / Maintenance | Long-Term Health / Maintenance |
| Calories | ~800/day | 800-1000/day | ~800/day | Normal Eating | No Counting |
| Carb Allowance | Moderately Low | <50g/day | ≤50g/day | Moderately Low | Moderately Low |
| Diet Style | Mediterranean | Very Low Carb, Med-Keto | Mediterranean | Mediterranean | Mediterranean |
| Ketosis | Can induce mild ketosis | Designed to induce deep ketosis | Can induce mild ketosis | Unlikely | Unlikely |
| Duration | Up to 12 weeks | Up to 12 weeks | Long-term | Long-term | Indefinite |
The Science Behind Carb Reduction
The Fast 800's effectiveness is partly due to "flipping the metabolic switch". By reducing carbohydrate intake, you deplete your body's glucose stores, forcing it to use fat for fuel through a process called ketosis. The Fast 800 Keto accelerates this process with stricter carb limits, while the other approaches induce a milder form of ketosis through calorie restriction and a moderately low-carb diet. The Mediterranean influence ensures a balance of nutrients, preventing many of the negative side effects often associated with traditional, higher-fat keto diets. The emphasis on protein and fiber also helps suppress appetite, making it easier to stick to the calorie goals.
Tips for Managing Your Carb Intake
- Plan Your Meals: To stay within your carb budget, especially on the Keto plan, careful meal planning is essential. The Fast 800 website offers structured meal plans for its members.
- Focus on Nutrient-Density: Prioritize non-starchy vegetables, lean protein, and healthy fats to maximize nutrition and satiety within your calorie limit.
- Stay Hydrated: Drinking plenty of water is crucial, especially when transitioning to a low-carb diet, as it helps minimize side effects like fatigue.
- Embrace Variety: Use a range of approved foods to keep your meals interesting and ensure you're getting all the necessary vitamins and minerals.
Conclusion: Finding the Right Carb Balance
Ultimately, the number of carbs you are allowed on the Fast 800 is determined by the specific program you choose. For rapid and potentially accelerated fat burning, the Fast 800 Keto's very low carb (<50g) approach is the path. For a more moderate and sustainable journey, the Very Fast 800, New 5:2, or Way of Life plans offer a moderately low-carb Mediterranean-style diet. Regardless of the path, the core principles revolve around reducing simple carbohydrates, prioritizing whole foods, and managing your intake for improved metabolic health and weight loss. For more resources and structured plans, consider exploring the official Fast 800 program online: The Fast 800 Programme.
