Intermittent Fasting 5:2 – Principles, Science and How To

Intermittent Fasting, 5:2 - Principles, Science and How To

Millions of people around the world are seeing excellent weight loss and health improvement results by following the intermittent fasting diet.

The diet goes by many names including 5:2 Intermittent Fasting, the Mosley Diet, the FastDiet, and The Dukan Diet. Although there are subtle differences between the diets, the principles remain the same.

In spite of the fact that research must still confirm many of the health claims made by these diets, the feast now, famine later approach to eating can potentially help you to drop pounds, improve health, and even live longer.

Add to that the fact that you can eat whatever you like for five days a week and restrict calories for two days a week and this diet starts sounding like an eating plan made in heaven.

Intermittent Fasting 5:2 – the Principles and Science Underlying

Intermittent fasting is by no means new. Fasting as a means to help treat disease is as old as the bible itself and it is a part of almost every religion.

Research published in The Journal of Diabetes and Metabolic Disorders, found that fasting on Ramadan helped to:

  • Regulate glucose homeostasis in the body
  • Improve insulin sensitivity
  • Lose weight for the individuals involved in the study.[2]

The science behind the diet is that as humans we evolved on a fast/famine diet. Tribes of old times did not have constant access to food but rather had a famine/feast type situation. When the tribe returned with meat, the tribe had a feast and then the tribe experienced famine before the next hunt.

5:2 Diet  – the Principles

The principles of this diet are quite simple and they are based on a documentary by British TV host and doctor Michael Mosley who wrote the book The Fast Diet based on his experience. Doctor Michael Mosley experimented with intermittent fasting to see if it helped him lose weight and feel better.

Mosley looked into the many recent studies on food restriction, weight loss, and aging, interviewing the primary researchers.

He tried various methods out on himself, starting with a full fast and eventually arriving at a ratio that worked for him: 2 days of partial fasting interspersed with 5 days of normal eating. The result: 20 pounds lost in nine weeks, along with a drop in cholesterol and blood sugar levels.

The 5:2 Diet involves eating as you normally do five days a week and restricting your calorie intake on remaining days to just 500 calories (2,100 kilojoules) for women and 600 calories (2,500 kilojoules) for men – well below the average recommendation of 2,000 a day for women.

The Effects of Fasting on the Body

The bottom line is that when you are trying to lose weight, you need your body to burn fat.

Intermittent Fasting and Hormone Regulation

Leptin, ghrelin, and insulin levels all play a very important role in how your body burns fuels for energy, what fuel it burns, and when your body tells you to eat. Individuals who are obese, for example, often have low insulin and leptin sensitivity that means they are hungry all the time and they don’t burn fat but rather store it.[3]

Intermittent fasting may help to normalize leptin and insulin levels. Insulin sensitivity is not only vital for weight loss, but it is also a very important factor for determining your risk of developing diseases like Type II Diabetes.

Intermittent Fasting and Weight Loss

Essentially, fasting may help to turn your body into a fat burning machine and in the process, it may help to regulate other important hormonal levels that help to reduce your risks of cardiovascular disease, diabetes, and many others. You can find more information on how to regulate your hormones to lose belly fat in my eBook Blast Your Belly Fat.

Intermittent Fasting – Bad News and Good News

The downside to Intermittent Fasting is that there are no hard and fast rules at this stage on the precise protocols or techniques needed for this diet. This is why much of the research is not accepted as proof of the advantages of fasting as a credible way to lose weight and to improve health.

But it’s not all bad news. You can’t argue with the results of weight loss of 8 pounds in 8 weeks according to a research published in Nutrition & Metabolism in 2012.[4] Although the studies are different in terms of periods used for fasting and calories consumed during the fasting period, most of the individuals who participated in the studies lost weight.

The Advantages of Intermittent Fasting

A healthy diet is vital for supporting your body, but there are distinct advantages and disadvantages to trying to follow certain types of diets.

It’s not as Restrictive as Other Diets

Trying to balance a “normal” life with a set of very specific diet instructions can be almost impossible at times.

If your career includes business lunches then you often find yourself picking at a salad, hoping the dressing is one that is allowed on your diet. Trying to enjoy a night out with friends has much the same result. Diets don’t last when you need to rearrange your life around your diet.

With the 5:2 diet or Intermittent Fasting, you can

  • Eat whatever you like (as long as you stick to the daily calorie requirements) although my personal recommendation is to stick to a healthy nutrition
  • Eat whenever you like
  • You also get to choose which days are your fasting days.

This means you have the freedom to arrange your week to suit your current lifestyle rather than rearranging your lifestyle to fit your diet.

For many individuals, ingredients in certain diets also pose a problem in terms of the diet. Ingredients may not be readily available or they are often quite expensive and not normally a part of your diet.

Since you can eat what you like, the fasting diets offer you an opportunity to eat what you normally eat, making it really easy to adapt to your current lifestyle. This can dramatically increase your chances of sticking to the diet in the long term.

But before you think this diet is perfect, there are a few potential side-effects or disadvantages associated with the diet.

Side Effects of the 5:2 Diet

Since the research on intermittent fasting is sparse, disadvantages of being on the 5:2 diet are based on individual experience and anecdotal evidence of the diet.

Side effects of the diet include the fact that some individuals experience a disruption in their sleeping patterns and may have trouble sleeping. Other individuals have developed bad breath similar to the type experienced by individuals on low carb diets. Some individuals have also experienced irritability, anxiety, and fatigue on fasting days. Dehydration may also be an issue for some individuals.[5]

You should also consult your physician before undertaking this diet, because fasting is not suitable or recommended for everyone. There are certain health conditions that can be adversely affected by periods of fasting.

How to Apply Intermittent Fasting to your Current Lifestyle

The simplicity of the diet and the fact you can eat pretty much what you like five days a week, are key to its popularity. Dieters are recommended to consume a ‘normal’ number of calories five days a week and then, for two, non-consecutive days, eat just 25% of their usual calorie total – 500 calories for women and 600 for men.

There are no restrictions on the types of food you can eat and it is suggested that women can expect to lose about a 1lb a week on the diet with men losing about the same if not a little more.

If you are interested in applying this type of diet technique to your lifestyle for weight loss purposes, or to improve your health, then it is best to invest in one of the books like the beginners guide for the 5:2 intermittent fasting diet to clarify the details of the diet and the techniques used.

Other Ways to Lose Weight without a Strict Diet

I’ve already written about other ways to lose weight without a strict diet:


Healthy and Natural World