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Intermittent fasting
Time to read: 23min

What is the 5:2 diet and how to do it

Nora Minno
"Natasha has spent the last 13 years immersed in the health and wellness industry as a qualified Clinical Nutritionist and copywriter. Natasha holds a Bachelor Degree in Health Science specializing in Nutritional Medicine and Postgraduate Qualifications in Public Health and Dermal Therapy. More information about Natasha: www.tashjordan.com"

Most associate intermittent fasting with abstaining from eating altogether, but that’s not always the case. Intermittent fasting is often done by alternating periods of eating and fasting for different lengths of time.

The 5:2 diet is a form of intermittent fasting, and as the name implies, you eat normally for five days and for two days you reduce your dietary intake to 500 – 600 calories a day. These two days are referred to as your fasting days. 

On fasting days, you may consume food in a variety of ways. Most will either choose two small meals or one large meal and a snack. The 5:2 diet could arguably be the poster child for intermittent fasting. The simplicity behind the diet and a growing body of scientific evidence make this form of intermittent fasting an intriguing way to improve overall health and lose weight.

Fasting on non-consecutive days is recommended. This helps to ensure you are getting a regular stream of nutritious foods, that will help maintain optimum health.

Non-consecutive fasting days also provide the flexibility that makes intermittent fasting so appealing – you essentially choose the days to fast that suit your lifestyle each week.

The 5:2 method may be easier for some to follow long term. This is because the 5:2 focuses on when you eat certain amounts of calories rather than what type of calories. This makes it feel less restrictive and you can follow it while still consuming the foods you enjoy.

What are the benefits of the 5:2 intermittent fasting?

Benjamin Franklin once said, "The best of all medicines is resting and fasting" and those proposed benefits have stood the test of time.

Here are some benefits that come from intermittent fasting.

Weight loss

Evidence has begun to support intermittent fasting as an effective way to lose weight, and weight loss is one of the most popular reasons people choose 5:2 intermittent fasting.

For example, one study compared the weight loss of a group of people who followed the 5:2 intermittent fasting method alongside a group of people who continuously restricted their calories for 7 days straight. The study found that the 5:2 diet was equally effective for weight loss as continuous calorie restriction. That’s great news for people who would rather just reduce calories 2 days per week rather than all 7 days per week!

Reduced risk of diabetes

With better weight control comes a range of additional benefits, including reduced risk of non-communicable diseases such as cancer, heart disease and diabetes.

Studies show that intermittent fasting and alternate-day fasting can be viable alternatives to continuous calorie restriction for promoting weight loss and a reduced risk of type II diabetes in overweight individuals.

Studies have also found that insulin resistance improved after just two weeks of following alternate day calorie restriction, similar to that of the 5:2 method.

Alzheimer’s disease

Alzheimer’s disease is associated with a reduction in brain glucose metabolism; this glucose metabolism is required for the cells in the brain to produce energy. Intermittent fasting places the body in a state of ketosis where the body starts to produce ketones. These ketones may serve as an alternative energy source for the brain in those with Alzheimer’s disease.

What to eat on fasting days

The beauty of the 5:2 diet is there is no one way to do it. You can adapt it to suit your needs and dietary preferences. As long as you are sticking to a few guidelines, you will still be getting all the benefits of intermittent fasting. Here are a few to follow:

Consume 500 – 600 calories a day

Food intake is drastically restricted on your two fasting days. You will consume between 500 -600 calories a day over two non-consecutive days.

Fast on non-consecutive days

Some choose to fast on consecutive days, but non-consecutive days are recommended. Not only does this provide flexibility but will also ensure a steady stream of nutrients.

Choose your meal

As long as you are sticking to 500 calories on your fasting days, you can choose how you would like to share those 500 calories throughout your day.

Some people like to skip breakfast and eat an early lunch and dinner; some like an early breakfast, a late lunch and nothing for dinner; some spread throughout the day and have three small meals.

Foods to include

Include foods that will make you feel full. These foods include those that are high protein and high fiber. Some great options include:

  • Vegetables – veggies are high in fiber and low in calories. This means you can eat more without driving your calories up. Opt for raw, steamed, or roasted veggies (with little or no oil) to make sure you’re not driving up the calorie count.

  • Lean proteins – think grilled chicken breast, white fish, eggs, legumes, lentils and tofu. Proteins like red meat or dark meat chicken will be higher in calories.

  • Berries – most berries are highly nutritious whilst being low in calories and can pack in loads of fiber to help keep you fuller longer. Some of the best include strawberries, blueberries and blackberries.

Foods to limit

Limiting highly processed or refined foods can help reduce inflammation. Also, these foods tend to give you less important nutrients per calorie, and when you are limited to only 500-600 calories per day, you want to focus on choosing nutrient-dense foods that will give you a bigger bang for your buck.

Also, higher fat foods such as deep-fried foods, animal fats, and cheese tend to be quite high in calories and won’t provide you with other important nutrients like fiber or antioxidants. Limiting these can help keep your calorie intake in check and will leave room to pack in more nutrient-dense foods into your diet.

If you’re looking for good sources of fat on your fasting days, try and choose fats that offer additional nutrients, for example, avocados are also a great source of fiber and eggs are a great source of choline and b-group vitamins.

Stick to the 25% rule

When fasting you will consume 500 calories a day as part of the 5:2 diet, this is based on a person’s diet where 2000 calories a day is consumed. If you consume less than 2000 calories, you would need to consume 25% of your daily calorie intake when you fast. For example - on a 1900 calorie-a-day diet, you would consume 475 calories on fasting days.

How to eat on regular days

In theory, when following the 5:2 diet, you could eat what you like on the remaining five days when you are not fasting, and promoters of intermittent fasting often portray images of binge-eating on off days.

This can create mixed and confusing messages about what you should be eating to stay healthy. 

It's important to eat a well-balanced diet, rich in important nutrients on those five non-fasting days. Healthy eating is always recommended to ensure you control calorie intake and maximize intake of all essential nutrients.

You can still eat a variety of nutritious foods without driving your calories up. All of the recommended above foods are healthy and low-calorie.

After all, when you eat healthy by giving your body a variety of important nutrients you can experience health benefits that can far surpass weight loss alone.

The 5:2 diet for weight loss

One of the biggest health challenges developed countries face is the problem of overweight and obesity. 5:2 intermittent fasting can be a viable and sustainable solution to individual weight loss.

The problem with many weight-loss diets lies in poor long-term compliance. The 5:2 diet offers a solution for those that struggle to stick to their weight loss diet. The 5:2 diet is flexible and takes away the feeling of restriction.

Generally, the 5:2 diet contains high protein, moderate fat and low carbohydrates; all of which play a beneficial role in weight loss. Although, research does suggest that some may overlook adequate amounts of micronutrients and fiber when intermittent fasting, so be sure to eat healthy most of the time when following the 5:2 diet.

Overall the 5:2 diet is considered safe and an effective weight loss strategy with the potential for long-term adherence.

Side effects of the 5:2 fasting diet

Fatigue from fasting

Some people may feel fatigued when they first start on the 5:2 diet, especially on fasting days. As your body starts to run low on energy sourced from stored carbohydrates, you may feel a slight decrease in blood sugar level, making you feel fatigued. As your body starts to use your fat stores as energy more efficiently, energy levels should stabilize. 

The fasting hunger

When you consume less food on your fasting days, you may start to feel those annoying hunger pangs. In the early days, you may find controlling this hunger a little more challenging.

Once you find what works best for you - whether skipping a meal at a particular time or including three small meals throughout the day - you will start to feel better.

You may need to look at what you are eating. Are you eating enough fiber and protein? Adjust the 5:2 diet to suit your unique daily needs and you will be breezing through fasting and hunger in no time.

Keep busy when fasting

Try to keep yourself busy during the times you are fasting. Sitting around will only make you want food more – boredom is a form of emotional eating and best avoided.

Who should avoid the 5:2 diet

Although the 5:2 diet is ok for most, some may need to avoid: 

Eating disorders

If you have an eating disorder or history of eating disorders, it is best to avoid any form of calorie restriction.

Blood sugar problems

In particular low blood sugar. Those prone to low blood sugar may find themselves a little dizzy or tired during the fasting periods. Diets that involve fasting may not be the best option.

Pre and postnatal

When you plan on becoming pregnant, are pregnant, or breastfeeding, your nutritional needs change and often increase. Fasting is not a good option for this stage of your life. It is best to wait until you are no longer planning pregnancy, pregnant or breastfeeding to start the 5:2 diet. 

Fertility

People who are looking to enhance their fertility may require a higher fat content in their diet. On fasting days, you will be following a low-fat diet, which may not be suitable for those looking to support fertility.

Summary

The 5:2 diet is one of the most popular forms of intermittent fasting because of its flexibility and less restrictive nature. The 5:2 diet has been proven successful for weight loss, reducing risk for diabetes, and reducing inflammation.

When you first start on the 5:2 diet, there may be a period of adjustment where you will need to find what works best for you, but if you stick to it, stay focused, and you will, over time, start to feel what all the health hype around fasting is about.

However, if you are uncertain if the 5:2 diet or intermittent fasting is suitable for you, it is always best to consult an appropriate health professional first.

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