Do Intermittent Fasting Diets Work?

Larry Scott Bodybuilder Getting from skinny to strong takes time and the right steps but is worth doing, and you can see great gains with this workout.

I’m sure many of you will have heard of intermittent fasting diets and how they can help you quickly lose weight, well today we are going to be looking at the ever popular 5:2 intermittent fasting diet.

Intermittent fasting is basically whereby you eat normally at certain times and fast during others.


The 5:2 diet is very simple, you eat normally Monday to Friday and fast all weekend, or alternate your two fasting days to suit you.

People who have been very successful with the diet state that it will not only help you lose weight but it also has other great health benefits too:

  • Longer Life
  • Improved brain function and protection against Alzheimer’s disease and¬† dementia
  • Protection from other diseases

Compared to other types of weight loss techniques the evidence to support this is limited.

intermittent fasting diet

There are many questions regarding this subject i’m sure you want answers too.

The Unknown

Intermittent Fasting is gaining huge popularity despite the fact there holes in it’s evidence:

  • It is unclear what pattern of Intermittent fasting is most effective i.e. 5:”, alternate day fasting or some other way.
  • No one really knows the recommended calorie consumption to use on fast days, it is supposed to be 500 for women and 600 for men on the 5:2 plan.
  • Is the plan sustainable long-term? Would people be able to do it for a long period of time? like all there life?
intermittent fasting diet

It is always worth considering any potential side effects of a new diet.



No one has really studied this so little is known about any side effects, some side effects that have been studies in various reports, these are:

  • Sleeping difficulties
  • Bad breath (a problem with many low-carb diets)
  • Anxiety
  • Dehydration
  • Daytime fatigue
  • Irritability

More research needs to be done to prove these side effects and see if they really do affect people in this manner.

If taking this on you will need to consider how it will effect your life during your fast days, you will be very hungry and fatigued , this could affect your work or ability to exercise which is a healthy part of any lifestyle.

It may not be suitable for pregnant women or people with existing health problems such as diabetes or eating disorders.

If you are serious about this diet plan then it would be best to consult with your doctor beforehand to see if it will have any effects on your health or well-being.

intermittent fasting diet

It is best to stack up the evidence to see if it will work for you.

5:2 Evidence

The 5:2 fast is very popular now, but little evidence still exists on it, There is one study however published in 2010 that showed the 5:2 plan tried on a group of women and the results where that the women lost a similar amount of weight to those on a calorie-controlled diet.

Researchers also tested for biomarkers that suggested a reduced level of risk from type-2 diabetes and other chronic diseases.

Another study done in 2012 found that the 5:2 plan might help reduce the risk of obesity related cancers like breast cancer, because of it’s popularity further research should be performed.

intermittent fasting diet

Can this really aid weight loss?

Any Evidence To Suggest Intermittent Fasting Aids Weight loss?

A published 2012 study took 30 obese women with known heart disease risk indicators.

After two weeks they were given a low calorie diet of liquid meals for 6 days of the week, followed by fasting for one day (consuming no more than 120 calories.).

After an eight week period the average weight loss was 8.8lb (4 kg) and 2.3 inches (6cm waist loss).

There are however a number of limitations to consider that might actually benefit ordinary people:

  • These women had a lot of motivation to stick with the plan as they were being closely monitored.
  • The women were at risk of heart disease, it is unknown how well a healthy person would cope with an extreme diet.
  • The follow-up period was only two months, it is now known whether this diet is sustainable long term.
  • 30 people is only a small sample size, a much larger sample including men is required to test how effective this is for most overweight or obese people.

Longer Life Evidence?

There are a good range of effects of Intermittent Fasting for combating the effects of aging, Most of the studies have involved rats, monkeys or mice. The problem with animal studies, especially rodents is that they only have a relatively short lifespan of a few years which does sort of make them ideal for longevity studies, carrying out more useful experiments in humans would take decades.

There was once a study in 1957 in Spain, 120 residents in an old people’s home were divided into two groups.

The first control group ate a normal diet, the other group ate a normal diet one day and a restricted 900 calorie one the next. After 3 years there were 13 deaths in the control group and 6 in the fasting group.

This study is still restrictive in it’s sample size, the death toll differences are more likely to be coincidence, this isn’t really a study that could be performed today as denying food to elderly in care in any country is frowned upon.


intermittent fast diets

How does an intermittent fast effect long term illnesses?

Can Fasting Prevent Cognitive Brain Deterioration?

All studies on Intermittent Fasting’s effects on cognitive diseases like Alzheimer’s and dementia were all performed on animals. In 2006 a study whereby mice had had there tissue changed to develop similar symptoms to Alzheimer’s.

Mice on a fasting diet showed slower deterioration compared to those on a normal diet (using a cognitive water maze test).

Although these studies on animals are intriguing they are hardly conclusive as the results will not always be the same for humans.

intermittent fasting diet

Can this fasting diet type help out preventing illnesses and diseases?

Will Intermittent Fasting Prevent Diseases?

A lot of the published research into the preventative effect of fasting have measured biological markers associated with cancer growth, this is a legitimate way to carry out biological studies but is not conclusive in terms of real-world effects.

A good example of this is with medications designed to lower blood pressure, great in the lab in theory  but never worked in the real world preventing any heart attacks.

A clinical 2007 review concluded that Intermittent Fasting may have a protective effect against type-2 diabetes and cancer but also stated that more research was needed into the effects on these illnesses.


Comparing the 5:2 program to other weight loss programs is difficult as evidence is so limited, if you are serious about doing this then consult with your doctor first as not everyone is suitable for fasting.

An Intermittent Fasting Diet may well work for you but it is best to take the diet in moderation to begin with to give your body time to adjust. Please feel free to comment below should you have any queries.

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