The 5:2 diet, also known as The Fast Diet, is a popular intermittent fasting diet popularized by British journalist Michael Mosley. It’s called the 5:2 diet because five days of the week are routine eating days, while the other two days restrict calories to 500-600 per day. Because there are no requirements about which foods to eat, but rather when you should eat them, this diet is more of a lifestyle. Many people find this way of eating to be easier to stick to than a traditional calorie-restricted diet.
Understanding the 5:2 Diet
Intermittent fasting (IF) is an eating pattern that alternates between fasting and eating windows. The most common approach is the 16/8 method, where you fast for 16 hours and eat within an 8-hour window. The 5:2 diet is another form of intermittent fasting. In the 5:2 diet, people eat normally 5 days a week, while eating 500kcal (females) and 600kcal (males) on 2 non-consecutive days.
How the 5:2 Diet Works: Calorie Guidelines
For five days per week, you eat normally and don’t have to think about restricting calories. On the other two days, you reduce your calorie intake to a quarter of your daily needs, which is about 500 calories per day for females and 600 for males. You can choose whichever two days of the week you prefer, as long as there is at least one non-fasting day in between them. One common way of planning the week is to fast on Mondays and Thursdays, with two or three small meals, then eat normally for the rest of the week.
It’s important to emphasize that eating “normally” does not mean you can eat anything. If you eat too much junk food, then you probably won’t lose any weight, and you may even gain weight. You should eat the same amount of food as if you hadn’t been fasting at all.
Flexibility of the 5:2 Diet
Part of the diet’s appeal is its flexibility. Instead of severely restricting the foods a person can eat, the 5:2 diet focuses on strict caloric restriction on only 2 days a week. This may help some people feel more satisfied with their diet, as they will not feel missing out all the time.
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Potential Health Benefits of the 5:2 Diet
There are very few studies on the 5:2 diet specifically. However, recent studies on intermittent fasting in general show impressive health benefits. One important benefit is that intermittent fasting seems to be easier to follow than continuous calorie restriction, at least for some people. However, the research is conflicting, with some noting that intermittent fasting and traditional dieting have similar adherence rates.
Weight Loss
If you need to lose weight, the 5:2 diet can be effective when done right. This is mainly because the 5:2 eating pattern helps you consume fewer calories. Therefore, it is very important not to compensate for the fasting days by eating much more on the non-fasting days. Intermittent fasting does not cause more weight loss than regular calorie restriction if total calories are matched.
Fasting protocols similar to the 5:2 diet have shown a lot of promise in weight loss studies. A 2014 review found that modified alternate-day fasting led to a weight loss of 3-8% over the course of 3-24 weeks. In the same study, participants lost 4-7% of their waist circumference, meaning that they lost a lot of belly fat. Intermittent fasting causes a much smaller reduction in muscle mass when compared to weight loss with conventional calorie restriction. A 2022 study of people with overweight or obesity found that adherence to the 5:2 diet was more effective than daily caloric restriction in promoting weight loss. A 2020 study similarly found modest improvements in weight management when following the diet.
Metabolic Health
Also, many studies have shown that different types of intermittent fasting may significantly reduce insulin levels. One 2011 study showed that the 5:2 diet caused weight loss similar to regular calorie restriction. Additionally, the diet was very effective at reducing insulin levels and improving insulin sensitivity. Several studies have looked into the health effects of modified alternate-day fasting, which is very similar to the 5:2 diet (ultimately, it’s a 4:3 diet).
A 2013 randomized controlled study in both moderate-weight and overweight individuals showed major improvements in the group doing 4:3 fasting, compared to the control group that ate as usual. After 12 weeks, the fasting group had:
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- Reduced body weight by more than 11 pounds (5 kg).
- Reduced fat mass by 7.7 pounds (3.5 kg), with no change in muscle mass.
- Reduced blood levels of triglycerides by 20%.
- Increased LDL particle size, which is a good thing.
- Reduced levels of C-reactive protein (CRP), an important marker of inflammation.
- Decreased levels of leptin by up to 40%.
Improved Blood Sugar Control
Fasting periods allow insulin levels to drop, helping to improve insulin sensitivity and blood sugar regulation. Lower insulin levels reduce the risk of insulin resistance, which is a key factor in developing type 2 diabetes. Studies suggest that intermittent fasting may help stabilize blood sugar levels, making it a promising approach for those at risk of metabolic disorders. A 2024 16-week trial reported that following a 5:2 diet resulted in improved blood glucose management compared with the use of the diabetes medications metformin and empagliflozin.
Heart Health
Heart disease risk factors such as high cholesterol, inflammation, and high blood pressure can improve with intermittent fasting. Studies indicate that fasting may help lower LDL (bad) cholesterol and triglycerides while maintaining or even increasing HDL (good) cholesterol. Fasting has also been shown to reduce markers of inflammation, which plays a role in heart disease development. By supporting metabolic health, intermittent fasting may contribute to better cardiovascular function over time.
Food Choices for Fasting Days
There is no rule for what or when to eat on fasting days. Some people function best by beginning the day with a small breakfast, while others find it best to start eating as late as possible. Generally, there are two meal patterns that people follow:
- Three small meals: Usually breakfast, lunch, and dinner.
- Two slightly bigger meals: Only lunch and dinner.
Since calorie intake is limited - 500 calories for women and 600 calories for men - it makes sense to use your calorie budget wisely. Try to focus on nutritious, high fiber, high protein foods that will make you feel full without consuming too many calories. Soups are a great option on fast days. Studies suggest that they may make you feel fuller than foods with the same calorie content or the same ingredients in their original form.
Foods to Include
It is vital to keep the body satisfied on fast days by eating foods that are rich in filling nutrients, such as fiber and protein.
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- Vegetables: For people who are just getting started on the 5:2 regimen, eating more fiber may help add bulk to meals and promote satiety.
- Protein: Protein is vital for staying full during fast days. People should focus on lean sources of protein without too much fat.
- Fruits: While most fruits are rich in natural sugars, dark berries, such as blackberries and blueberries, may fulfill sweet cravings without adding many calories.
- Soup: Soup is a great tool for fast days, as the added water and spices from the broth may help a person feel more satisfied without eating too many calories.
- Water: Water is vital every day, but during fast days it may help stretch the time between meals and keep a person from feeling hunger pangs.
- Coffee or tea: Plain, unsweetened coffee and tea are acceptable during fast days. However, some people find that coffee or tea stimulates their digestive system, making them feel hungry. Herbal tea is another option and is a great way to increase the person’s water intake.
Here are a few examples of foods that may be suitable for fast days:
- A generous portion of vegetables
- Natural yogurt with berries
- Boiled or baked eggs
- Grilled fish or lean meat
- Cauliflower rice
- Soups (for example, miso, tomato, cauliflower, or vegetable)
- Low calorie cup soups
- Black coffee
- Tea
- Still or sparkling water
Foods to Avoid
To avoid extra calories or using up the daily calorie limit on foods with fewer nutritional benefits than some other, more nutrient-dense ones, a person may wish to avoid the following foods on fast days:
- Processed foods, which are typically refined and high in calories
- Refined carbohydrates, such as breads, pastas, and white rice
- Excess fats, including cooking oils, animal fats, and cheese
Recipes for Fasting Days
Here are a few breakfast, lunch, and dinner recipes to consider for a variety of eating patterns:
Low-Calorie Vegan Recipes
- Breakfast: Scramble ¼ block of firm tofu with ½ cup of chopped green peppers. Serve with ½ cup of raspberries on the side.
- Lunch: Mix ½ cup of canned chickpeas with ¼ of an avocado. Wrap the mixture in 2 romaine lettuce leaves.
- Dinner: Mix together ½ cup of quinoa (cooked in water), ½ cup of chopped broccoli, and ½ cup of chopped red peppers.
Low-Calorie Vegetarian Recipes
- Breakfast: Scramble 2 egg whites with 1 slice of nonfat Swiss cheese, and serve with 1 cup of raspberries on the side.
- Lunch: Eat 2 tablespoons of peanut butter on 1 slice of whole-wheat toast.
- Dinner: Bake ¼ block of firm tofu with herbs and spices, and serve with 1 ½ cups steamed broccoli.
Low-Calorie and Low-Carb Recipes
- Breakfast: Scramble 3 egg whites with 1 slice of nonfat Swiss cheese and ½ cup of chopped green peppers.
- Lunch: Mix 3 ounces (oz) of lean grilled chicken breast with ¼ of an avocado and wrap in 2 romaine lettuce leaves.
- Dinner: Bake 3 oz of salmon and serve with 1 cup of steamed cauliflower.
Low-Calorie Recipes for Omnivores
- Breakfast: Scramble 4 egg whites and serve with 1 slice of whole-wheat toast.
- Lunch: Mix 3 oz of canned white tuna (water-packed) with ¼ of an avocado.
7-Day Intermittent Fasting Meal Plan (16/8 Method):
This 7-day meal plan follows the 16/8 intermittent fasting approach, with an eating window from 12:00 PM to 8:00 PM. Each meal is packed with nutrients to keep you full, energized, and satisfied. Feel free to adjust meal timings based on your preferences and lifestyle.
Day 1
- Breakfast (12:00 PM): Scrambled eggs with avocado and whole-grain toast
- Snack (3:00 PM): Greek yogurt with almonds and berries
- Lunch (5:30 PM): Grilled chicken salad with quinoa and olive oil dressing
- Dinner (7:30 PM): Salmon with roasted sweet potatoes and steamed broccoli
Day 2
- Breakfast: Oatmeal with peanut butter and banana
- Snack: Hard-boiled eggs and hummus with cucumber slices
- Lunch: Spicy turkey meatballs with roasted veggies
- Dinner: Thai beef lettuce wraps
Day 3
- Breakfast: Spinach and cheese omelet with a whole-grain wrap
- Snack: Apple slices with almond butter
- Lunch: Grilled chicken with brown rice and sautéed greens
- Dinner: Italian meatball soup
Day 4
- Breakfast: Chia pudding with walnuts and cinnamon
- Snack: Cottage cheese with berries and pistachios
- Lunch: Chicken fajita bowl with quinoa
- Dinner: Baked salmon with roasted cauliflower
Day 5
- Breakfast: Avocado toast with poached eggs
- Snack: Roasted chickpeas with turmeric
- Lunch: Lentil soup with a mixed greens salad
- Dinner: Grilled steak with mashed sweet potatoes
Day 6
- Breakfast: Protein smoothie with almond milk, banana, and flaxseeds
- Snack: Dark chocolate and nuts
- Lunch: Mediterranean quinoa bowl with feta cheese and chickpeas
- Dinner: Baked cod with roasted zucchini and garlic butter
Day 7
- Breakfast: Greek yogurt with granola and berries
- Snack: Boiled eggs with avocado slices
- Lunch: Vegetable stir-fry with tofu and brown rice
- Dinner: Chicken tortilla soup with a side salad
Is the 5:2 Diet Safe? Who Should Avoid It?
Although intermittent fasting is very safe for healthy, well-nourished people, it does not suit everyone. Some people should avoid dietary restrictions and fasting completely. These include:
- Individuals with a history of eating disorders.
- Individuals who often experience drops in blood sugar levels.
- Pregnant people, nursing people, teenagers, children, and individuals with type 1 diabetes.
- People who are malnourished, underweight, or have known nutrient deficiencies.
- People who are trying to conceive or have fertility issues.
Furthermore, intermittent fasting may not be as beneficial for some females as it may be for males. Some females of reproductive age have reported that their menstrual periods stopped while they were following this type of eating pattern.
For most healthy adults, intermittent fasting is a safe and effective way to support overall health. However, it’s not for everyone. Pregnant or nursing individuals, those who are underweight, or people with a history of eating disorders should avoid fasting. If you have diabetes, low blood pressure, or any other medical condition, it’s important to consult your doctor before starting. Listening to your body is key-if you feel weak, dizzy, or overly hungry, adjust your approach.
People who are prone to low blood sugar or easily feel dizzy or fatigued if they do not eat may not want to follow a diet that involves fasting. Pregnant or chestfeeding people must also avoid fasting. Children and teenagers should avoid fasting unless under the direct guidance of a doctor, as their bodies are still developing. Anyone with a chronic condition, such as diabetes, can consult a doctor before trying any diet that includes fasting.
Tips For Safe And Effective Fasting
Intermittent fasting can be a tool for better health, but it’s important to do it in a way that supports your body’s needs. By following these key tips, fasting can become a sustainable and enjoyable part of your lifestyle:
- Start Slowly: Jumping into long fasting periods too quickly can leave you feeling fatigued and frustrated. Instead, ease into intermittent fasting by gradually increasing your fasting window over a few weeks. Start with a 12-hour fast and slowly work toward 14 or 16 hours as your body adapts. This approach helps minimize hunger, irritability, and energy crashes while allowing your metabolism to adjust naturally.
- Stay Hydrated: Hydration is crucial while fasting, as your body still needs fluids to function properly. Drinking plenty of water can help curb hunger, support digestion, and prevent dehydration-related headaches. Herbal teas and black coffee (without sugar or cream) are also fantastic options that won’t break your fast. If you’re feeling sluggish or lightheaded, adding a pinch of salt to your water can help replenish electrolytes and keep your body balanced.
- Focus On Nutrient-Dense Meals: What you eat during your eating window matters just as much as when you eat. Prioritize whole, nutrient-dense foods that include lean proteins, healthy fats, and fiber-rich carbohydrates. These nutrients help stabilize blood sugar levels, keep you full longer, and prevent energy crashes. Skipping highly processed foods and excess sugar will make fasting easier and support better overall health.
- Don’t Overeat In Your Eating Window: It can be tempting to eat large portions or indulge in unhealthy foods after a long fast, but overeating can lead to digestive discomfort and negate the benefits of fasting. Instead, focus on mindful eating by starting with a balanced meal and paying attention to hunger cues. Eating slowly and choosing whole, satisfying foods will help prevent bloating, sluggishness, and unnecessary calorie intake.
- Listen To Your Body: Intermittent fasting should work for you, not against you. If you feel overly fatigued, irritable, or experience frequent dizziness, your fasting window may be too long. Adjust your approach by shortening your fast, increasing your nutrient intake, or trying a different fasting method. Everyone's body responds differently, so finding the right balance is key. If fasting ever feels overwhelming, it’s okay to take a step back and reassess. Your health and well-being always come first.
Potential Downsides of the 5:2 Diet
- You may overeat on non-fasting days: One of the biggest challenges is not consuming too many calories on non-fasting days. “The hunger from fasting can carry over into the next day,” Zumpano cautions.
- It can lead to nutritional deficiencies: If you’re not paying close attention to what you’re eating, you could miss out on important nutrients. For example, there’s little room in the diet for healthy fats on fasting days. So, you need to make up for that on non-fasting days. Salmon, nuts and seeds are good sources of healthy fats. A multivitamin can also help replace missing vitamins and minerals. But they may cause nausea if you don’t take them with enough food. When possible, it’s best to get the nutrients you need from your foods, Zumpano advises.
- There’s no guide for what to eat: The simplicity of the 5:2 diet can be both a pro and con. Yes, it’s easy to follow. But the lack of guidance on what to eat can make it easy to eat the wrong foods. Consuming less nutritious and inflammation-triggering foods can wipe out the benefits of the 5:2 diet and your overall success.
- You may not feel great on fasting days: In addition to being hungry, people on the 5:2 diet report a range of symptoms on fasting days, such as: Fatigue, Headaches, Irritability, Poor concentration, Lightheadedness or dizziness.
Sample Recipes for the 5:2 Diet
Here are a few examples of recipes that align with the principles of the 5:2 diet, keeping in mind the need for low-calorie, nutrient-dense options on fasting days and balanced meals on non-fasting days.
Recipes Suitable for Fasting Days (Approximately 500-600 Calories)
Spiced Carrot & Lentil Soup: A delicious, spicy blend packed full of iron and low in fat. It's ready in under half an hour, or can be made in a slow cooker.
Ingredients:
- 1 tbsp olive oil
- 1 onion, chopped
- 2 carrots, chopped
- 1 tsp cumin
- ½ tsp ground coriander
- Pinch of chilli powder (optional)
- 100g red lentils
- 600ml vegetable stock
Instructions:
- Heat the olive oil in a large saucepan. Add the onion and carrots and cook for 5 mins until softened.
- Stir in the cumin, coriander, and chilli powder (if using) and cook for 1 min more.
- Add the lentils and vegetable stock. Bring to a boil, then reduce heat and simmer for 20 mins until the lentils are tender.
- Blitz with a hand blender until smooth. Season to taste.
Chickpea, Tomato & Spinach Curry: A super healthy, vegan curry that accounts for 2 of your 5-a-day and is low in calories.
Ingredients:
- 1 tbsp coconut oil
- 1 onion, chopped
- 2 cloves garlic, minced
- 1 inch ginger, grated
- 1 tsp curry powder
- 400g canned chopped tomatoes
- 400g canned chickpeas, drained and rinsed
- 100g spinach
Instructions:
- Heat the coconut oil in a large pan. Add the onion and cook until softened.
- Add the garlic and ginger and cook for another minute. Stir in the curry powder.
- Add the chopped tomatoes and chickpeas, then simmer for 15 minutes.
- Stir in the spinach and cook until wilted.
Broccoli and Kale Green Soup: This super healthy soup combines broccoli and kale with ginger, coriander and turmeric for a nutrient dense and low-fat lunch.
Ingredients:
- 1 tbsp olive oil
- 1 onion, chopped
- 2 cloves garlic, minced
- 1 inch ginger, grated
- 1 head of broccoli, chopped
- 100g kale, chopped
- 600ml vegetable stock
- Coriander and turmeric to taste
Instructions:
- Heat the olive oil in a large saucepan. Add the onion and cook until softened.
- Add the garlic and ginger and cook for another minute.
- Add the broccoli and kale, then pour in the vegetable stock. Bring to a boil and simmer until the vegetables are tender.
- Season with coriander and turmeric to taste. Blitz with a hand blender until smooth.
Recipes Suitable for Non-Fasting Days
Paillard of Chicken with Lemon & Herbs: Pounding meat until thin and flat is a great technique for barbecued chicken breast, as it ensures it won’t dry out.
Ingredients:
- 2 chicken breasts
- 1 tbsp olive oil
- Juice and zest of 1 lemon
- Mixed herbs (such as thyme, rosemary, parsley), chopped
Instructions:
- Pound the chicken breasts until thin and flat.
- Mix the olive oil, lemon juice, lemon zest, and herbs.
- Marinate the chicken in the mixture for at least 30 minutes.
- Barbecue or grill the chicken until cooked through.
Spiced Chicken & Pineapple Salad: This colourful salad is packed with contrasting flavours and textures.
Ingredients:
- 1 grilled chicken breast, sliced
- 1 cup pineapple chunks
- ½ red onion, thinly sliced
- 1 bell pepper, sliced
- Mixed greens
- Sweet chilli sauce and coriander for dressing
Instructions:
- Combine all ingredients in a bowl.
- Dress with sweet chilli sauce and coriander.
Teriyaki Salmon Parcels: These easy steamed fish parcels with Japanese seasoning are an ideal way to get kids in the kitchen.
Ingredients:
- 2 salmon fillets
- Teriyaki sauce
- Vegetables (such as broccoli, carrots, and bell peppers), sliced
Instructions:
- Place a salmon fillet on a sheet of parchment paper.
- Top with teriyaki sauce and vegetables.
- Fold the parchment paper to create a sealed parcel.
- Steam or bake until the salmon is cooked through.