The 5:2 Diet | Benefits, Side effects, What to Eat

The 5:2 diet is a popular diet that is based on the concept of intermittent fasting. This is a method of eating in which you eat normally at certain times and then you also fast for the remaining time.

This diet is basic and uncomplicated.

You eat normally for 5 days of the week and then fast on the remaining two days. Fast days do not need to be together, they may be spaced out if this is an easier option for the individual. Fasting does not mean you eat no food however, the diet recommends a significantly reduced calorie intake on these days, specifically 500 calories for women and 600 for men.


5:2 Diet – Advantages


There are many perceived benefits by advocates of this diet including:


?  Weight loss

?  Increased lifespan

?  Improvements in cognitive function


Weight loss


There is a distinct lack of peer reviewed research to support these claims directly in humans as the majority of research is on intermittent fasting in different forms – also, many studies also use animals rather than human subjects. This is not to say that benefits do not exist, simply that science has not conducted sufficient research to give solid credibility to some of the claims made with specific forms of intermittent fasting.

With that said, intermittent fasting in general may well be an alternative that is more successful to some people than normal calorie restriction on a daily basis when the desired outcome is weight loss.


5:2 Diet – Disadvantages


Just as there is little to no peer reviewed evidence on the 5:2 diets effectiveness with regards its claims to disease prevention and reduction, there is also little to no peer reviewed evidence highlighting negative effects. However, anecdotal reports have included:


– Difficulty in sleeping

– Bad breath

– Irritability

– Day time sleepiness – presumably on fasting days.




If you’re fasting and due to be in work on that day, you may want to consider swapping your fasting day to your days off if it may have a negative impact on your ability to function in work, especially if you are a beginner to fasting.

Studies using obese women have shown in alternate day fasting, (which is slightly different to the 5:2 diet in that there is a continuous cycle of a day on fasting and a day off it through the week) participants felt hungry in the first week but this reduced greatly by the second week, in whWomen's workoutsich they found the process much more comfortable at that point.

Physical activity habits of the women were unaffected by the intermittent fasting throughout the duration of the study, but this may not be the case with trained athletes.

Weight loss in the women was relative to the degree of energy restriction which would be expected.
This particular diet may have an impact on the ability to exercise at desired intensities on fasting days if you are undergoing heavy training. It may also have a negative effect on recovery if training is undertaken due to the calorie allocation being so low.


5:2 Diet – Meal ideas


Limiting your calories does not mean you have to make boring food choices!

Some useful foods to have close to hand include low fat, high protein options such as quark and cottage cheese – these foods tend to be very filling without being high in calories. You can make a tasty dessert by adding fruit to both and a scoop of protein powder. This will also satisfy a craving for something sweet while packing a punch of both fast and slow digesting protein.

Studies have shown BCAA’s to be very effective at avoiding muscle loss in times of calorie reduction, and so they may be a useful supplement to include in your diet.


protein desserts


? Lean meats such as chicken and turkey can be marinated to add extra flavour.

? Low calorie marinades can be made using low fat yoghurt and spices and even lemon juice.

? Fish is also a great choice and there are some great dishes you can make by adding rice and vegetables or even a sweet potato.

? Omelettes are another delicious choice for fast days, you can reduce the amount of whole eggs you use and replace some of them with egg whites to lower the calories from a traditional omelette made exclusively with whole eggs.Salad

? Side salads can make an excellent accompaniment especially in the summer months, and you can add extra flavour by making your own dressings.


By making clever food choices you can make a very filling meal even with such a low calorie allowance, many people are surprised at just how many calories can be in conventional processed foods many people eat at mealtimes presuming that they contain far fewer calories than they do in reality.




It should also be noted that there are very few peer reviewed studies on fasting in athletic populations, the majority focuses on obese participants who may have different outcomes from the diet than the latter.



However, there have been studies which have shown health benefits in trained males who undertook intermittent fasting and they benefited by having reduced insulin resistance


Take home message


The 5:2 diet may have promote benefits for those wishing to improve their health and begin in a weight loss journey – however, there does need to be peer reviewed research conducted to support the various claims made specific to this form of fasting.

However – there is evidence for alternate day fasting that is promising in both humans and animals which would in theory imply the 5:2 diet may also be of advantage to individuals wanting to lose weight!

Everyone’s’ bodies work differently – give it a go and see if it’s for you!


5:2 Diet



Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you’re concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.



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