5:2 Fasting Diet: The Answer To Fast Weight Loss?

One of the latest diet crazes to hit the news at the moment is the 5:2 Fasting diet. Opinion is divided whether this diet is the best thing for health and weight loss or is just another fad diet. We take a look at the facts.

5:2 Fasting DietThe 5:2 fasting diet is the latest in a long line of so-called miracle diets. It first came to the attention of the public, following the BBC TV Horizon Programme Eat, Fast and Live Longer, which was broadcast in August 2012.

The TV presenter, Dr Michael Mosley was looking into the health benefits of fasting, and became convinced of it himself, going onto write his own book, which has subsequently become very popular.

He is credited with inventing the 5:2 diet as an effective method of fast weight loss. The system is built around the idea of regularly going without food over a set period of time, also referred to as fasting.

What is Intermittent Fasting?

The basic idea of this diet is centred on Intermittent Fasting and essentially means that you have food free periods in your life as part of your usual routine. This idea has been around for about a decade and can come in a variety of forms.

Small meal sizeSome people practice Alternate Fasting which means that you eat normally one day, and eat nothing, or very little for the next, However the 5:2 diet, as designed by Michael Mosley is proving to be more popular because it is relatively easier to follow.

How it works is simple. You eat normally for five days and practically starve yourself for two days on an extremely limited diet where the maximum daily calorie intake is around 600 calories for men and 500 for women.

Champions of the diet say that switching to this method of eating has many health benefits including:

  • Weight loss
  • Increased life span and longevity.
  • Improved immune system to disease and illness
  • Prevention against degenerative conditions such as Alzheimer’s.
  • A detox effect causing brighter clearer skin and similar.

The 5:2 diet is being heavily promoted at the moment with diet plans published by the Sunday Times. Books and articles promoting this weight loss method are currently very popular and much talked about in the media.

How Do You Follow the Diet?

The diet appeals to people because there are no rules! You are free to eat and drink what you like for five days a week as long as you restrict your calorie intake on the two “fasting days” and keep calorie intake to 500 calories for women and 600 calories for men.

The Fast Diet“Eat what you like most of the time” is the tag line for Michael Mosley’s book “The Fast Diet”, and of course, this does sound easy. The idea that you can eat and drink whatever you like for five days a week and still keep fit and healthy is appealing. It sounds easy.

There are numerous 5:2 diet plans and books on the market and these are full of recipe suggestions and eating plans for the two days fast. You are advised to choose your Diet days carefully and use days where you have an “easy day” planned, rather than days where you need to be busy and perform well at work, exercise or go to social occasions.

The food free days makes for scary reading and followers are advised to miss meals such as breakfast or lunch in order to keep within the extremely low calorie count, thus going against all health advice. Drinks are mainly restricted to black teas, coffees, and water.

A typical fast day menu would be something like;

  • Breakfast 2 cups of tea or coffee – less than 50 calories
  • Lunch – home-made soup (no bread) approximately 193 calories, or perhaps something like two scrambled eggs and a slice of ham
  • Dinner – grilled fish and vegetables or similar.

The Pros and Cons to Intermittent Fasting

Eating like this twice a week may help you lose weight but it does go against medical advice, which is to have a healthy diet every day that you can live with. There is a strong possibility that you will end up binge eating on the normal diet days and many people will struggle to keep within 500 or 600 calories on the fasting days.

Some people using the diet have reported very low energy levels, becoming faint with hunger, irritable and unwell during the fasting days and according to user reviews, most people find themselves “cheating” during the fasting days. One women reported that she usually had one main meal, using up the 500 calories, and then went to bed for the rest of the day!

Some people have had more positive effects and report that their appetite decreases over the normal eating days. Initial weight loss is usual but this diet does not suit everyone and most people struggle to stay on it.

Pros of 5:2 Fasting Diet

  • Appetite may decrease over time
  • Shown to have positive weight loss benefits

Cons of 5:2 Fasting Diet

  • Hard to maintain, requiring strong will power
  • Low energy levels
  • Hunger pains and feeling faint
  • Feeling ill during fasting days

New Fasting Diet Supplement

In August 2013 a new diet supplement arrived that claims to make following a fasting diet that much easier. The 5:2 Fast Formula is targeted at anyone following an intermittent or fasting diet, and works to make following those fasting days easier to handle.

Read our in-depth article on the 5:2 Fast Formula supplement here.

The Effects of Fasting on your Hormones

According to research, fasting can have beneficial effects upon health. The National Institute on Aging in Baltimore Maryland has been investigating and their studies reveal that going without food can lower insulin growth hormone (IGF -1) and lowered IGF -1 may help protect the brain from Parkinson’s disease Alzheimer’s and other conditions. There is some evidence that it can improve cognitive ability too.

We need high levels of this growth hormone when we are young in order to develop but according to animal testing, high levels of IGF-1 in later life cause ageing.

One of the main bodies of research has been based upon the inhabitants of an Ecuadorean village, who lack this vital growth hormone and are as a consequence less than four feet tall. However, they also have a strong immunity to disease including cancer and diabetes and appear to live to very old age.

The reason attributed for these health benefits is the lack of IGF-1. The idea of fasting is that when you deprive your body of food, it lowers your IGF -1-hormone levels and this causes your body’s cells to repair rather than grow. The lowering of the IGF -1 hormone causes the repair genes to start functioning.

Professor Valter Longo of the University of California who has studied the Ecuador village people for the past 22 years believes that lowering IGF -1 has immense health benefits with regards life span and immunity for disease.

A variety of research is currently being carried out on the effects of IGF-1 and long-term health, but so far there is any little real evidence.

Is the 5:2 Fasting Diet Dangerous?

Some health experts are not so sure about the benefits of Intermittent Fasting and believe that the 5:2 diets may create health problems. There may be some health advantages but so far, there is a lack of evidence to prove that fasting will help promote long-term health.

There are concerns that a Fasting diet may damage long-term fertility so it should be avoided by women looking to conceive.

There is no evidence available to prove that fasting will prevent the onset of Alzheimer’s disease and there are health concerns that a reduction in the IGF -1 hormone may increase the risk of other medical conditions.

Fasting for health has not been fully tested on humans. Most of the research into this has been carried out by animal testing and the few control groups who have been monitored have involved very small numbers of people. Further research is necessary.

Many health and nutrition authorities are concerned that this is an intrinsically unhealthy relationship with food and could lead to conditions such as Anorexia and the NHS, although being cautious in their reaction to the diet, recommends that maintaining a healthy balanced diet every day is the best option for health.

Common Side Effects

There are numerous side effects to this diet. According to users, these include;

  • Sleep disturbances
  • Dehydration
  • Anxiety
  • Irritability
  • Extreme hunger
  • Inability to concentrate
  • Increased stomach acid and queasiness

Many people will not be suitable for the diet. It will only be suitable for those who are in good physical shape and who do not have any underlying health conditions. It is not suitable for women who are pregnant or trying to conceive, people who suffer from diabetes, low blood pressure or any history of eating disorders.

If you are considering trying this diet, it is advisable that you see your doctor first.

Champions of the diet often cite religious fasting as promoting good health and longevity. However, studies carried out on the effects of Islamic fasting – Ramadan have thrown up some mixed findings.

So is the 5:2 Diet Worth a Try?

The 5:2 Fasting diet is the latest in a long line of fad diets and the NHS are not recommending it a viable method for losing weight.

All medical advice is to maintain a sensible, healthy diet as part of your life and one major problem with this diet is that it is far too extreme and most people will be unable to follow it.

The days of starvation can have a severe impact on daily life and will have to be planned for in advance. Many people struggle with hunger pangs and it can be a miserable experience, which will probably lead to yo yo weight gain once the diet has been abandoned. Time will tell whether supplements like the 5:2 Fast Formula will make fasting diets easier to follow and as consequence led to weight loss.

Medical opinion is that the only way to lose weight successfully and keep it off is by improving your diet and lifestyle. This is more effective than constant yo yo eating habits each week. Putting your body into starvation mode can actually make weight loss harder as your body’s metabolism slows as a consequence of food shortages.

It may be found in the future, that the reduction of IGF-1 will have positive effects on long-term health, but this diet is not a realistic method of weight loss for most people. There may also be long-term side effects to intermittent fasting as a lifestyle that have not yet been identified.

Have Your Say

7 comments on '5:2 Fasting Diet: The Answer To Fast Weight Loss?'

  1. I’ve been on the 5:2 for 6 weeks and lost over a stone now, its just hard not to eat bad foods on your normal days, seeing weight loss each week is a good reminder why you are doing it

  2. I never saw program but did read Mimi Spencer’s column and bought the book I have been doing 4.3 for 5weeks and lost 1stone I’ve never felt better and can see this as a way of life I don’t have any side effects at all, in fact I’m walking 5 times per week and for someone who’s morbidly obese that’s quite something.

  3. I watched Dr. Mosley’s documentary on PBS, then bought both “The QOD Diet” by Dr. John Daugirdas and “The Alternate Day Diet” by Dr. Johnson. I semi-fast Monday, Wednesday, Fridays by keeping my total caloric intake below 400 & other days eat normally–but not fried foods, empty calories, etc. After 3 weeks I’m 6 lbs lighter & find alternate fasting a breeze! The fast days I feel more energetic & don’t miss eating 3x a day. Hopefully I can stick with it long-term.

  4. If one uses MediFast food supplements on the fasting days, it is painless to eat only 500/600 cal/day without feeling hungry. This is easier than just the MediFast diet alone.

  5. I have tried this for 2 weeks but apart from the really bad breath, fatigue, extreme hunger & binge eating the following day, I feel no better. I have a very sensitive stomach and thought this would help but it has exaggerated my symptoms the next day after the fast day.

  6. I have done this 5:2 diet for a 3weeks first 2 worked really well, saw I visible difference, then had a lovely meal out, now all the weight lost I have gained again! We are talking 5 pound here. So does this mean, it will always happen? Will it come off again only to go back on again???

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