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5 2 Diet Review - 14 Things You Need to Know

The 5:2 diet is a version of intermittent fasting, allowing dieters to eat almost anything they want for five days out of the week, then eat almost nothing for two specific days in that specific week. They claim the time-restricted feeding plan is effective for weight loss. Though results may be promising for calorie restriction, can intermittent fasting ensure dieters get all the nutrients they need?

On top of a lack of research on some potential users, such as nursing mothers, our research team is concerned about the impact of fasting on the body’s health. Our research team dove into the science behind the diet plan to find out its effectiveness and safety. These are the results of that research.

5 2 Diet can be purchased through their Official Site.

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What is the 5:2 Diet?

5:2 Diet is when you eat what you want for five days in a week, and then you virtually eat nothing for two days in that specific week. This means meals can be skipped in any consecutive two days or altered intermittently on different days of the week. This 5:2 Diet plan is like fasting for two days within a week, intending to keep the body fit. It is also often referred to as time-restricted feeding.

The 5:2 Diet is also called the 5/2 Diet. This dieting plan entails intermittent fasting. This diet is a cautiously scheduled eating plan within some fasting days (specifically two days) every week, and not a full-fasting diet of water only.

Does It Work?

  • Intermittent Fasting — “Human trials suggest that IF may have beneficial effects on weight, body composition, cardiovascular biomarkers, and aging.”
  • Intermittent Fasting and Human Metabolic Health — “Studies in rodents and other nocturnal mammals support the hypothesis that intermittent fasting and restricting the availability of chow to the normal nighttime feeding cycle improves metabolic profiles and reduces the risk of obesity”
  • Intermittent Fasting: The Choice for a Healthier Lifestyle — ” studies found that intermittent fasting was effective for short-term weight loss among normal weight, overweight and obese people”

5 2 Diet Competitors

Paleo Diet
Weight Watchers WW
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History of the 5:2 Diet

According to the Western Journal of Medicine, fasting and intermittent fasting have been practiced by most civilizations since at least the start of recorded history.

There are several modern diets involving intermittent fasting as a key weight loss component. One such diet is the 5:2 Diet.

The 5:2 Diet is a book written by Kate Harrison, a British journalist who had trouble losing weight.

She started intermittent fasting and saw immediate results. With this diet, she lost 31 pounds and has kept the weight off since 2012.

Intermittent fasting diets existed before Kate Harrison wrote the 5:2 Diet Book, but there was no book outlining the approach.

She wrote the 5:2 Diet Book, followed by The Ultimate 5:2 Recipe Book, The 5:2 Good Food Kitchen, 5:2 Your Life: Get Happy, healthy, and Slim, The Dirty Diet, and 5:2 Veggie & Vegan.

Michael Mosley, another British journalist, previously popularized the diet. He also wrote a book that was released around the same time as Kate Harrison’s.

5 2 Diet Customer Testimonials

5:2 Diet Basics

For the five days of eating, the dieter doesn’t have to think about the caloric deficit. Then for the two days of fasting, the 5 2 diet rule requires a restriction in the calorie levels.

Another basic rule in this dieting plan is choosing any days of the week to observe the fasting.

The usual practice for users of the 5 2 diet plan is to observe the fast on Mondays and Thursdays, eat a small meal with fewer calories, and then eat normally for the rest of the week. You can start fasting at any time of day—for instance, 3 PM on Monday to 3 PM on Tuesday.

It is expedient to note that on the five days of eating normal, dieters are not at liberty to consume whatsoever that comes their way, especially junk food. A high intake of junk food is known to reduce the noticeable successful impact of undergoing the 5:2 Diet plan.

Diet Guide

5:2 Diet Guide

The popularity of this 5:2 Diet is because those implementing it can eat whatever they want to for five days.

There is no restriction on what to eat in the allowed days. However, for this 5 2 guide, dieters eat fewer calories during these five days.

In this view, Kate Harrison, a BBC reporter, in her 5 2 diet book, suggests that for the two days of skipping meals, only 25% of calories in the amount of 500 calories for women dieters and 600 for men, should be used while undergoing the dieting therapy.

The original 5:2 Diet plan does not require dieters to go full fasting for two days.

For five days a week, one tends to eat normally and doesn’t have to think about restricting calories. There are two methods of how one can begin the 5:2 Diet, namely:

The 16/8 diet plan is another modified version of the 5:2 Diet. The 16/8, otherwise referred to as lean gains protocol, suggests avoiding breakfast and limiting eating each day to an eight hour period.

For instance, the timing could be eating from 12 pm to 8 pm and fasting for the remaining 16 hours.

The Eat-Stop-Eat is another approach, which entails fasting between one or two days within a week. For example, dinner can be skipped to another dinner time the next day.

Meal Plan

5:2 Diet Meal Plan

Being on a diet doesn’t mean you stop what you love eating. All you need to do is reduce the number of foods you consume containing large amounts of calories.

This is done by reducing your diet into small portions–breakfast under 100 calories, lunch under 200 calories, and dinner under 200 calories to meet the 500-calorie meal plans for the 5 2 diet.

5:2 Diet Meal Plan

The types of foods include a sandwich, spinach, cauliflower leaves, and natural yogurt with berries, grilled fish, black coffee, and tea.

Intermittent Fasting

Is the 5:2 Diet an Intermittent Fasting Diet?

The 5 2 diet employs fasting (or time-restricted feeding) mainly as a way of reducing weight, as calories are cut down for a participant in the program.

This fasting makes the human body return to repair mode where cells are replaced. Also, skipping meals during a fast is not the same as starvation, where damaged cells are not repaired, but sometimes body fat is accumulated.

Consistently observing a fast on the selected two days for a week and consuming fewer calories during these selected days make the 5 2 diet a planned fast rather than starvation.

This is a form where you don’t need to eat everything presented to you every day. It is a form of weight loss where one chooses to eat anything he or she wants to for five days in a week and diet for the remaining two days of the week.

Rather than considering the 5:2 Diet a fast, some believe it is more of a guide for an eating pattern that tells the dieter when to eat, not necessarily what to eat.

Weight Loss

5:2 Diet and Weight Loss

The 5:2 Diet can effectively reduce one’s weight, as fewer calories are consumed each week, especially during the two-day fast period.

Consumers should be are careful not to overcompensate for days of fasting by eating too much during the remaining five days.

Some studies say that fasting can be a great way to lose weight. According to research published in the International Journal of Obesity“Intermittent fasting or alternate-day fasting may be an option for achieving weight loss and maintenance.”

When current calorie restriction was observed, the two fasting days have a small effect in this regard.

By combining the 5:2 Diet with moderate exercise, observable impacts were achieved.


5:2 Diet Warnings/Cons

There are no studies on fasting and pregnant or nursing women. However, since the body needs vital nutrients at this time, fasting could cause issues. It could also affect the baby or mother’s blood pressure, weight, blood sugar, digestion, and other factors.

This applies especially to those with blood-sugar related issues. This also applies to people with heart issues. Many chronic conditions could be negatively affected by fasting. Fasting could cause heartbeat irregularities and affect blood sugar levels.

Fasting causes the body to change how it metabolizes and utilizes foods or medications. Therefore, always talk to your doctor and explain the plan.

No studies have been conducted on the health benefits or side effects of children’s fasting. Growing children need more nutrients than adults. As their bodies are not fully developed, fasting may interfere with hormone or other processes.


5:2 Diet Compared to Other Diet Programs

This is very different from most diet plans. Most diet plans restrict certain food groups like sugars, fats, carbohydrates, and overall calories.

This diet allows any foods, including high sugar or fatty foods. However, this diet includes two full days of fasting per week.

This diet does not require you to count calories, but it is allowed. It is important to remember that although you can eat anything, you should not overindulge.

You should also not eat more calories on normal days than you normally would.

The fast days do not require complete fasting. They allow around 500-600 calories per day. They can be done consecutively or split up during the week.

Some alternatives include:


Some diet plans have hard rules to follow, sometimes unnecessarily, with many rules to cope with. The abundance of difficult-to-follow rules usually leads to a high failure rate for dieters.


Other diet plans have no room for flexibility, coupled with no consideration for the changes to the environment and human situations. Such programs are difficult to succeed in.


Participants are mostly scared away from many diet programs as they are introduced to exotic foods that they are not used to and have never eaten.

Lack of a tailored and specific structural plan for different individuals is a difficulty.

Some diet programs only recommend a uniform standard to be followed, with little or no consideration for personalized or customized diet recommendations.

5:2 Diet Compared to Other Diet Programs unrealistic

The same avoided list of food is presented as those to be avoided for every set of participants. This uniformity makes such programs very ineffective for different classes and set of people.

The plan relies on a severe caloric deficit to produce results.

The difference with the 5:2 Diet program as compared to others has made its success rate high. This high score is attributed to the following benefits:


Even though your calories are restricted on a fast day, what you eat is not. Fasting days should include nutrient-dense foods to maximize health benefits. However, any of the following foods can be eaten.

  • Vegetables – All vegetables are allowed in this diet.
  • Fruits – Unlike some diets, fruit is not restricted.
  • Carbohydrate-rich foods – Rice, bagels, pasta, or bread.
  • Meat – Vegetarian options exist, but all meat options are allowed.
  • Beans and grains – All beans and grains are options on this diet.
  • Full-fat foods – Cheese, fattier cuts of meat, whole milk, and yogurt
  • Alcohol – This diet does not restrict alcohol consumption.
  • Junk Foods – French fries, ice cream, cakes, chips, and more.


Flexibility is always important in a diet. Most people fail diets because they feel restricted and overwhelmed by changes to the diet.

This plan does not limit or avoid any foods or food groups. Therefore, if you want to eat chocolate cake or donuts, you can.

Physiologically, people often want food more when it is banned. So, this diet avoids that issue.

However, the diet does recommend healthier eating for extra weight loss and health reasons.

Portion sizes should be moderate but adequate. Food choices should focus on healthy options with the occasional indulgence.

Overall, this diet allows you to eat the foods you love. It feels less restrictive and can be helpful for that reason. For the week, you should still see a reduction in calories due to the two fast days.


The practicability feature of the 5 2 diet has made it successful with many participants. You are not expected to eat special modified food or make your life difficult by eating what you would normally hate due to lack of taste or unpleasantness.

There are no dos and don’ts in the 5:2 Diet program list. Participants are only presented with few and simple choices to make to increase the diet plan’s success rate.

Specific and personalized: When you are allowed to eat your regular food and those that taste good to you, then the motivation to continue with such a dieting program remains high.

Online Program

Online 5:2 Diet Program

There are different platforms of programs on the 5:2 Diet. Among these, we have:


ifast12.com is very popular. It runs a twelve-week program of the 5:2 Diet by inculcating the successful approach of Michael Mosley combined with high-intensity interval training (HIIT).

iFast-12 in Australia is an innovative and dynamic medical program offered by HealthLab Australia. However, the program is not meant as a substitute for care by your usual health professional, who should be consulted for all symptoms outside this 12-week IFast-12 program.

There are also tools that aid participants in the 5:2 Diet to work successfully.

The Fast Diet

Thefastdiet.co.uk has an online calculator for users. Its BMI is a digital calculation tool that predicts the allowed body fat for those who want to exercise while undergoing the 5:2 Diet plan.

The tool measures the height and weight of a person to give an accurate result.

This tool’s lapses are that it does not give accurate answers for pregnant women and those below five feet in height.

The different activities levels and exercises are calculated using the BMI, indicating results for different users, including those categorized into:

They may not be active athletes, but they are serious about exercise.

Diet Details

More 5:2 Diet Details

After detailing the ins and outs of the 5:2 Diet, there are some glaring facts dieters should not dismiss. Keep in mind:

  • Fasting is not a better option than reducing calories.
  • People with medical conditions should NOT follow this plan.
  • The diet may be difficult to follow, especially if you travel or eat out often.
  • The pattern of two large meals or three smaller meals may leave many hungry.
Time Restricted Eating

What Is Time-Restricted Eating?

According to Cell Metabolism, time-restricted eating refers to the theory that the body processes foods differently at certain times of the day or after intermittent fasting

Most ancestral peoples did not eat 3 meals a day all year long. Most had periods of food shortages, which resulted in long hours without food or extended periods with limited food intake.

In one study, mice were given unlimited access to high-fat, high-sugar foods. However, the length of time the mice had access to these foods limited. The mice with the shortest access to foods gained less weight even if they consumed the same calories as those with the longest access.

According to the Journal Translational Medicine, the theory is that the body burns more fat during fasting periods, especially stored fat. The downtime may give the body the opportunity to do things it can’t normally do. There may be more to the digestion and metabolic process of the body that we do not understand.

Most time periods restrict eating to an 8- to 12-hour window. Some suggest a 6-hour window. Other options are eating normally one day and with a restrictive window the next, or alternating days throughout the week.

One benefit of intermittent fasting or time-restricted eating is that it doesn’t seem to put the body into starvation mode, says The American Journal of Clinical Nutrition. Restricted calorie diets can often result in muscle loss and a plateau in weight reduction. The body compensates since it thinks there is a food shortage. Intermittent fasting or TRE does not appear to trigger the phenomenon.

What Users Are Saying

What Users Are Saying

“I did it for about 6 months in 2019. It was a good way to get into fasting without too much pressure. I am always busy at the weekend (pre- Covid) so found that kept my focus off food I would then have one meal in the evening for my 500 calories. I went down two dress sizes not sure on weight as I didn’t have scales. The challenge I found was that it was easy to get out of the habit of fasting. All I needed was a change in my routine one week to not do the fasting days at all. Also having 5 days where you can eat normally meant I sometimes overate and undid the good work. I find time restricted eating every day is better for me as I am not organised enough to plan each weeks fasting and normal eating.”

“It is best to eat healthy, but any diet with whatever name works because it puts the dieter in a calorie deficit, calorie counting is the only way of losing weight that’s worked for me because it’s non restrictive. I’ve lost 7lbs eating still whatever I want, it’s just that whatever I want is counted into my daily calorie allowance. Sure sometimes I have to decide if having a hot choc with cream and sprinkles is worth replacing an evening snack of crisps and a chocolate bar, but I like that I feel in control without feeling restrictive. Every restrictive diet I’ve tried has resulted in me losing weight and then gaining it back when I inevitably give up because it’s too hard!!”

“I’ve been on the 5:2 for a year now, and I like it. It was hard at first I would like buy a huge bag of beef jerky and weigh out in grams what I was eating and hope the jerky would fill me, or drink a muscle milk or two and call that my meals. But over the quarantine and lockdowns I got a better hang of it. I eat whatever now… so long as it’s under 500ish calories.”

5 2 Diet Ingredients
Bottom Line

The Bottom Line on the 5:2 Diet

So, what’s the final take on the 5:2 Diet? I was initially intrigued by this system, but I was disappointed in the end. The lack of scientific support concerns me, which leaves me with doubts about recommending it. It’s also harsh to expect followers to binge or fast for weight-loss.

If you want to lose weight and keep it off, we suggest a program using clinically-tested methods with strong customer support.

Among the best products we’ve seen this year is one called Noom. It’s a program that combines one-on-one coaching, food logging, exercise tracking, virtual communities and more. Dieters report some fantastic results.

The makers behind Noom are confident you’ll see results so they’re offering a free trial offer.

Learn More About Noom »
5 2 Diet Review
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5 2 Diet

What are the side effects of 5:2 Diet?

Some of the potential side effects of the 5:2 Diet include headaches, jitteriness, nausea, vomiting and dehydration.

What are the ingredients in 5:2 Diet?

The ingredients in the 5:2 Diet are common foods. You will eat lean protein, vegetables and limited amounts of carbohydrates.

Does 5:2 Diet work?

The company states there is no scientific research proving the 5:2 Diet is an effective weight-loss solution, although eating fruits and vegetables could possibly help you lose weight.

How much does 5:2 Diet cost?

The 5:2 Diet costs $9.99.

How should I use the 5:2 Diet?

You should take the 5:2 Diet by fasting for two days and eating smaller portions for five days.

Where can I buy 5 2 Diet?

5 2 Diet can be purchased using their Official Site.

Can I use the 5:2 Diet if I have a health condition?

Those with health conditions, people with medical conditions of any kind, anyone under 18 years of age or women who are pregnant or nursing should contact a healthcare professional prior to starting a weight-loss plan, including the 5:2 Diet.

Do I need to count calories on the 5:2 Diet?

Yes, you will need to count calories on the 5:2 Diet. The guide teaches dieters how to weigh food, use the calorie table and read ingredient labels.

What is the maximum amount of calories on the 5:2 Diet?

The maximum amount of calories on the 5:2 Diet is 600. The company states that some users consume fewer than 500 calories.

What beverages can I drink on the 5:2 Diet?

You can drink water, tea and coffee on the 5:2 Diet.

Can I increase calories on the 5:2 Diet if I exercise?

No, you can’t increase calories on the 5:2 Diet if you exercise on fasting days. You don’t count them when feeding.

Are the fasting days consecutive on the 5:2 Diet?

No, the fasting days don’t need to be consecutive on the 5:2 Diet. Typically, dieters break up the days they fast.

Do I count calories on non-fasting days?

No, you don’t need to count calories on non-fasting days. Some dieters limit the amount of calories on feed days as to not over compensate.

Does the 5:2 Diet come with a guarantee?

The company states there is no guarantee with the 5:2 Diet.

Do you know of any special deals or discounts on the 5:2 Diet?

The company states there are no special deals or discounts on the 5:2 Diet.

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