What is the Fast 800 Diet?

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What is the Fast 800 diet?

The Fast 800 diet is a structured weight loss programme that focuses on consuming only 800 calories a day in its initial stages. It incorporates elements of intermittent fasting and Mediterranean-style eating to support metabolic health, making it more than just a quick fix diet.

The approach was developed by Dr. Michael Mosley, a British physician, journalist, and advocate of evidence-based dieting. His extensive research on intermittent fasting and weight management has informed this innovative approach to health.

How does the Fast 800 diet work?

The diet woks in phases:

1. Intensive calorie restriction phase: This kick-starts weight loss by limiting calorie intake to 800 per day. While 800 calories may sound restrictive, the diet is designed to be nutritionally balanced. However, it is only recommended for short-term use under proper guidance. Typically, this phase lasts between two and twelve weeks, depending on individual weight-loss goals and health conditions. Prolonged calorie restriction can lead to nutritional deficiencies and metabolic slowdown. Preparation for this phase involves meal planning, stocking up on low-calorie, nutrient-dense foods, and mentally preparing for a significant dietary adjustment.
2. 5:2 phase: It is a form of intermittent fasting where you consume a normal calorie intake for five days of the week and reduce it to 800 calories on two non-consecutive days. On fasting days, meals should focus on lean protein, vegetables, and healthy fats to ensure you stay full despite the calorie restriction. On the other days, gradually increase calorie intake while incorporating more Mediterranean-style foods.
3. Maintenance phase: Focuses on sustainable eating habits to maintain weight loss while continuing to follow the principles of the Mediterranean diet. In this phase, the diet shifts to balanced Mediterranean-style meals without strict calorie counting, ensuring long-term adherence.

To maintain results, the program emphasizes permanent changes, such as regular exercise, mindful eating, and incorporating nutritious foods into daily life.

What are the principles of the Fast 800 diet?

1. Calorie reduction to 800 per day: By reducing calorie intake to 800 per day, the diet initiates rapid fat loss while maintaining lean body mass. This amount has been shown to be effective without being overly restrictive for most healthy people. Pregnant or breastfeeding women, children, and individuals with specific medical conditions should avoid the diet. Consulting a healthcare professional is essential before starting.
2. Incorporating Mediterranean diet principles: The diet emphasizes nutrient-dense foods such as lean proteins, healthy fats, whole grains, and vegetables. These foods not only provide essential nutrients but also contribute to improved heart health and reduced inflammation.
3. Transitioning from the intensive phase to maintenance: Rather than maintaining strict calorie limits indefinitely, the diet transitions participants to a sustainable lifestyle. This includes more flexible eating patterns, helping to prevent weight regain.

What are the benefits of the Fast 800 diet?

• Rapid weight loss: Participants often experience significant weight loss during the first few weeks due to the reduced calorie intake and shift in metabolic processes.
• Improved insulin sensitivity: The diet has been shown to enhance the body’s ability to regulate blood sugar, making it particularly beneficial for people with type 2 diabetes or those at risk.
• Heart health benefits from Mediterranean diet elements: By incorporating heart-healthy fats, whole grains, and lean proteins, the diet supports cardiovascular health and reduces cholesterol levels.
• Reduced risk of metabolic diseases: The Fast 800 diet helps lower the risk of conditions like type 2 diabetes, fatty liver disease, and metabolic syndrome.

The number “800” isn’t random—studies show that this calorie threshold is effective for promoting weight loss without compromising essential nutrient intake in most healthy individuals.

How to start the Fast 800 diet?

Start by choosing meals rich in lean proteins, vegetables, and healthy fats. Pre-planning meals can ensure you stay within the calorie limit without compromising on nutrients.

• Include lean meats, fish, eggs, tofu, and legumes to meet your protein requirements.
• Incorporate olive oil, nuts, seeds, and avocados to ensure adequate fat intake.
• Focus on non-starchy vegetables like leafy greens, broccoli, and zucchini for volume and nutrients without high calories.

While strict calorie counting is necessary during the intensive phase, it becomes less critical as you transition to the maintenance phase.

What are the potential side effects of the Fast 800 diet?

Gastrointestinal discomfort: Sudden dietary changes can cause bloating or digestive upset, especially in the initial stages.

Fatigue during the initial phase: Reduced calorie intake may lead to fatigue or decreased energy levels. This typically improves as the body adapts.

Muscle loss due to poor macronutrient balance: Without careful planning, the diet may lead to muscle loss. Including adequate protein can help prevent this.

Example menu for each phase

Creating balanced and satisfying meals is essential for success on the Fast 800 diet. Each phase of the program requires careful attention to portion sizes, macronutrient composition, and food choices to maximize results while maintaining health and well-being. Below are detailed meal examples tailored to each phase of the diet, providing practical guidance for your weight loss journey and long-term success.

Phase 1: Very Low-Calorie Phase (800 calories daily)

The very low-calorie phase is designed to initiate rapid fat loss while maintaining essential nutrients. Meals focus on lean protein, healthy fats, and non-starchy vegetables to maximize satiety within calorie limits.

Breakfast (200 calories)

• Greek Yogurt Bowl
  • 120g full-fat Greek yogurt
  • 50g mixed berries
  • 5g chopped almonds

Lunch (250 calories)

• Grilled Chicken Salad
  • 100g grilled chicken breast
  • 2 cups mixed salad greens
  • 1/4 avocado (30g)
  • 1 tsp olive oil and lemon juice dressing

Dinner (350 calories)

• Mediterranean Stir-Fry
  • 100g grilled salmon
  • 1 cup steamed broccoli
  • 1/2 cup cooked quinoa
  • 1 tsp olive oil
  • Herbs and spices for flavor

Tip: Prepare for this phase by planning meals, stocking up on low-calorie, nutrient-dense foods, and mentally preparing for significant dietary adjustments.

Phase 2: Intermittent Fasting Phase (e.g., 5:2 plan, 800 calories on fasting days)

Fasting days focus on nutrient-dense, low-calorie meals to help manage hunger while staying within the 800-calorie limit.

Fasting Day Menu (800 calories)

Breakfast (150 calories)

• 2 boiled eggs
• Handful of baby spinach sautéed in 1 tsp olive oil

Lunch (250 calories)

• Lentil Soup:
  • 1 cup cooked lentils
  • 1 cup vegetable broth
  • 1/2 cup diced vegetables (carrot, celery, onion)

Dinner (400 calories)

• Zucchini Noodles with Turkey Meatballs:
  • 3 turkey meatballs (100g)
  • 1 cup spiralized zucchini
  • 1/2 cup marinara sauce (no added sugar)
  • 1 tsp Parmesan cheese

or Keto Meal Chocolate that provides a variety of micronutrients and 389kcal, with zero sugar and 3.8g of fiber.

Non-Fasting Days Menu (1,200-1,500 calories)

Increase portions slightly, add a healthy snack (e.g., a handful of nuts or a small piece of fruit).

Phase 3: Maintenance Phase (Mediterranean Diet, 1,500-2,000 calories)

This phase focuses on balanced, Mediterranean-inspired meals to maintain weight loss and support long-term health.

Breakfast (300 calories)

• Avocado Toast:
  • 1 slice whole-grain bread
  • 1/2 avocado
  • 1 poached egg

Lunch (450 calories)

• Grilled Chicken Buddha Bowl:
  • 100g grilled chicken
  • 1/2 cup cooked brown rice
  • 1 cup mixed veggies (e.g., roasted sweet potatoes, kale, and peppers)
  • 1 tsp tahini dressing

Dinner (600 calories)

• Baked Salmon with Veggies:
  • 150g baked salmon
  • 1 cup roasted Brussels sprouts
  • 1/2 cup mashed sweet potatoes

Snack (100-150 calories)

Small handful of mixed nuts (20g) or an apple with 1 tsp almond butter.

Comparing the Fast 800 Diet to Other Diets

When choosing a diet, it’s essential to consider your personal goals, lifestyle, and preferences. The Fast 800 diet is unique in its combination of calorie restriction, intermittent fasting, and Mediterranean principles. However, other popular diets, such as the ketogenic diet, the 5:2 intermittent fasting plan, and very low-calorie diets (VLCDs), offer alternative approaches to achieving similar results. Here’s a closer look at how these diets compare.

Fast 800 vs ketogenic diet

The ketogenic diet emphasizes a high-fat, moderate-protein, and very low-carbohydrate intake to induce ketosis, a state where the body burns fat for energy instead of carbohydrates. While this approach is effective for managing type 2 diabetes, reducing epileptic seizures, and promoting fat loss, it can be challenging to sustain long-term due to its restrictive nature. In contrast, the Fast 800 diet prioritizes calorie restriction alongside a balanced macronutrient intake, incorporating healthy fats, lean proteins, and low-carbohydrate vegetables. It transitions participants to a Mediterranean lifestyle, known for its sustainability and evidence-backed health benefits, including improved metabolic and cardiovascular health.

Fast 800 vs 5:2 diet

The 5:2 intermittent fasting plan allows for regular eating five days a week, with calorie restriction on two non-consecutive days. While this diet is flexible and easy to follow, it doesn’t provide detailed guidance on meal composition or overall nutrient balance. The Fast 800 diet builds upon the 5:2 structure by including an initial intensive calorie-restriction phase and emphasizing Mediterranean-style meals, ensuring a well-rounded and sustainable approach to weight loss and long-term health.

Fast 800 vs very low-calorie diets (VLCD)

Very low-calorie diets (VLCDs) also focus on rapid weight loss by reducing daily caloric intake to under 800 calories, similar to the intensive phase of the Fast 800 diet. However, VLCDs often rely heavily on meal replacements, which can lack the variety and nutrient density of whole foods. In contrast, the Fast 800 diet encourages nutrient-dense, whole-food-based meals, providing essential vitamins and minerals to support overall health while achieving weight loss goals.

Each of these diets has its strengths, and the best choice depends on your specific needs and preferences. For those seeking a structured, holistic, and sustainable approach, the Fast 800 diet offers a balanced solution with long-term benefits for weight management and overall well-being.

Ensuring Nutritional Balance on the Fast 800 Diet

While the Fast 800 diet is designed to promote rapid weight loss and metabolic health, its calorie-restricted nature may lead to potential nutrient deficiencies if not carefully planned. Proper attention to macronutrients, fiber intake, and essential vitamins and minerals is crucial for maintaining overall health and achieving sustainable results. Below, we outline the key nutrients to monitor and recommend supplements to support your journey on the Fast 800 diet.

Macronutrients:

• Protein: If the diet is not well-balanced, insufficient protein intake can occur, especially in vegetarian or vegan adaptations.
• Fiber: With reduced food intake, dietary fiber may be insufficient, affecting digestion.

Micronutrients:

• Calcium: Commonly low due to reduced dairy or fortified plant-based alternatives.
• Iron: Particularly a risk for women or vegetarians, as calorie restriction may limit iron-rich foods like red meat and leafy greens.
• Vitamin D: Sunlight exposure and/or supplementation are often necessary for most adults, as food sources alone are usually inadequate.
• B Vitamins: Including B12, especially if a significant portion of the diet is plant-based.
• Magnesium: Found in nuts, seeds, and whole grains, which may be consumed in limited quantities.
• Zinc and selenium: Often tied to reduced intake of seafood, nuts, and seeds.

Recommended Supplements for the Fast 800 Diet

1. Multivitamin: A good-quality multivitamin to cover common gaps, especially B vitamins, and vitamin C. Choose a supplement free from sugar such as our vitamin B + C complex or Keto Greens, that provides a variety of micronutrients and only 36 kcal.
2. Vitamin D: 800-4,000 IU daily (or as recommended by your doctor) to support bone health and immunity. One drop of Be Keto’s vitamin D supplement provides 2.500 IU.
3. Omega-3 Fatty Acids: If the diet lacks fatty fish, consider 1,000-2,000 mg of a fish oil or algae-based omega-3 supplement (EPA/DHA).
4. Electrolytes: feeling symptoms of keto flu? Remember to take your daily electrolyte dosage. More on this subject in this Keto Flu and how to avoid it.

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