Does the 5:2 intermittent fasting diet work?

Note – this article, originally written in January 2013, was updated in May 2013.

The 5:2 diet is an increasingly popular diet plan with a flurry of newspaper articles and books being published on it in the run up to Christmas 2012 and in January 2013.
The diet first reached the mainstream via a BBC Horizon documentary called Eat, Fast and Live Longer, broadcast in August 2012.
The 5:2 diet is based on a principle known as intermittent fasting (IF) – where you eat normally at certain times and then fast during other times.
The 5:2 diet is relatively straightforward – you eat normally five days a week, and fast on the other two days.

Champions of the 5:2 diet claim that other than helping people lose weight, 5:2 diet can bring other significant health benefits, including:

• increased life-span
• improved cognitive function and protection against conditions such as dementia and Alzheimer’s disease
• protection from disease

However the body of evidence about 5:2 diet and intermittent fasting is limited when compared to other types of weight loss techniques.

What we don’t know about intermittent fasting

Despite its increasing popularity, there is a great deal of uncertainty about IF with significant gaps in the evidence.
For example, it is unclear:

• what pattern of IF is the most effective in improving health outcomes – 5:2, alternative day fasting, or something else entirely different
• what is the optimal calorie consumption during the fasting days – the 5:2 diet recommends 500 calories for women and 600 for men, but these recommendations seem arbitrary without clear evidence to support them
• how sustainable is IF in the long-term – would most people be willing to stick with the plan for the rest of their lives?

Are there any side-effects from intermittent fasting?

Little is known about possible side-effects as no systematic attempt has been made to study this issue. Anecdotal reports of effects include:

• difficulties sleeping
• bad breath (a known problem with low carbohydrate diets)
• irritability
• anxiety
• dehydration
• daytime sleepiness

However, more research would be needed to confirm these side-effects and their severity.
If you are fasting, you may want to think about how fasting will impact on your life during your fasting days. You are likely to be very hungry and have less energy and this could affect your ability to function (such as at work), in particular it may affect your ability to exercise which is an important part of maintaining a healthy weight.
Also, IF may not be suitable for pregnant women and people with specific health conditions, such as diabetes, or a history of eating disorders.
Because it is a fairly radical approach to weight loss, if you are considering trying IF for yourself, it is wise to speak to your GP first to see if it is safe to do so.

Evidence about the 5:2 diet

Despite its popularity evidence directly assessing the 5:2 model of intermittent fasting is limited.
But since this article was originally written in January 2013 we have been alerted to research, led by Dr Michelle Harvie, which did look at the 5:2 model.
In one study carried out in 2010 the researchers did find that women placed on a 5:2 diet achieved similar levels of weight loss as women placed on a calorie controlled diet.
They also experienced reductions in a number of biological indicators (biomarkers) that suggest a reduction in the risk of developing chronic diseases such as type 2 diabetes.
A further study in 2012 suggested that the 5:2 model may help lower the risk of certain obesity-related cancers, such as breast cancer.
The increasing popularity of the 5:2 diet should lead to further research of this kind.

Evidence about other forms of IF

There is some degree of evidence about the potential benefits of other forms of IF – albeit with some limitations.
It should be stressed that our assessment of the evidence was confined to entering a number of keywords into Google Scholar and then looking at a small number of studies which we felt would be useful to explore further.
We did not carry out a systematic review (though arguably, it would be useful for researchers to do so). So the information provided below should be taken in the spirit of us trying to provide an introduction to some of the evidence and science of IF – not an exhaustive 'last word' on the topic.

Is there any evidence that intermittent fasting aids weight-loss?
One of the most recent pieces of research on intermittent fasting is a 2012 study which recruited 30 obese women known to have pre-existing risk factors for heart disease.
After an initial two week period they were then given a combination diet of low calorie liquid meals for six days of a week (similar to Slim Fast diet products) and then asked to fast for one day a week (comsuming no more than 120 calories).
After eight weeks, on average, the women lost around 4kg (8.8lb) in weight and around 6cm (2.3 inches) off their waist circumference.
However, there are a number of limitations to consider when looking at this as evidence that it might be a generally beneficial thing to do for most ordinary people, including that:

• These women may have had increased motivation to stick with the diet because they knew their weight would be monitored (this is a psychological effect that slimming clubs make use of).
• The women had been told that they were at risk of heart disease. It is uncertain how well most of us would cope with such as extreme diet.
• The follow-up period was short – just two months. It is not clear whether this diet would be sustainable in the long-term or whether it could cause any side effects.
• 30 people is quite a small sample size. A much larger sample – including men – is required to see if intermittent fasting would be effective in most overweight or obese people.

Is there any evidence intermittent fasting increases life-span?
There is quite a wide range of work on the effects of IF on combating the effects of aging, but almost all of these studies involved either rats, mice or monkeys. One big problem with studies in animals – particularly rodents – is that they are only expected to live for a few years, this makes them ideal subjects for longevity studies. However, to carry out similar, more useful experiments in humans, requires decades-long research to gain credible results.
In an unsystematic look at the evidence, we find only one study involving humans: a 2006 review of an experiment actually carried out in 1957 in Spain.
In this 1957 study, 120 residents of an old people’s home were split into two groups (it is unclear from the study whether this was done at random). The first group (the control group) ate a normal diet. The second group (the IF group) ate a normal diet one day and then a restricted diet (estimated to be around 900 calories) the next.
After three years there were 13 deaths in the control group and only six deaths in the IF group.
This study is again limited by the small sample size meaning that the differences in death are more likely to be the results of a statistical fluke. Also, many experts would feel uneasy about issuing dietary guidelines based on a study over half a century old with unclear methods. It is unlikely that this experiment could be repeated today – denying food to elderly people in residential care is unlikely to be looked at kindly by an ethics committee.

Is there any evidence intermittent fasting prevents cognitive decline?
It seems that all of the studies on the supposed protective effects of IF against conditions that can cause a decline in cognitive function (such as dementia or Alzheimer’s disease) involve animals.
For example, a 2006 study involved mice that had been genetically engineered to develop changes in brain tissue similar to those seen in people with Alzheimer’s disease.
Mice on an IF diet appeared to experience a slower rate of cognitive decline than mice on a normal diet (cognitive function was assessed using a water maze test).
While the results of these animals tests are certainly intriguing, animal studies have inherent limitations. We can never be sure that the results will be applicable in humans.

Is there any evidence intermittent fasting prevent diseases?
Much of the published research into the potential preventative effects of IF involve measuring biological markers associated with chronic disease, such as insulin-like growth factor-I (IGF-I) – known to be associated with cancer.
Using these kinds of biological surrogates is a legitimate way to carry out research, but they do not guarantee successful real-world outcomes.
For example, some medications that were found to lower blood-pressure readings taken in laboratory conditions failed to prevent strokes once they had been introduced for use in the healthcare of patients in the world.
A 2007 clinical review looking at the effects of IF in humans in terms of ‘real-world’ health outcomes concluded that IF (specifically, alternative day fasting) may have a protective effect against heart disease, type 2 diabetes and cancer. However, it concluded ‘more research is required to establish definitively the consequences of ADF (alternative day fasting)’.

Conclusion

Compared to other types of weight loss programmes the evidence base of the safety and effectiveness of the 5:2 diet is limited.
If you are considering it then you should first talk to your GP to see if it is suitable for you. Not everyone can safely fast.
Other methods of weight loss include:

• eating a healthy balanced diet with at least five portions of fruit and vegetables a day
• taking regular exercise
• quitting smoking if you smoke
• drinking alcohol in moderation

Article Created & Edited by NHS Choices  http://www.nhs.uk/news/Pages/NewsIndex.aspx.

Links to the headlines

The power of intermittent fasting. BBC News, August 5 2012
The 5:2 diet: can it help you lose weight and live longer? The Daily Telegraph, August 16 2012

Links to the science

Harvie M, Howell A. Energy restriction and the prevention of breast cancer. Proceedings of the Nutrition Society. Published online March 12 2012
Harvie M, Pegington M, Mattson MP, et al. The effects of intermittent or continuous energy restriction on weight loss and metabolic disease risk markers: a randomised trial in young overweight women. International Journal of Obesity. Published online October 5 2010
Kroeger CM, Klempel MC, Bhutani S, et al. Improvement in coronary heart disease risk factors during an intermittent fasting/calorie restriction regimen: Relationship to adipokine modulations (PDF, 291.4Kb). Nutrition & Metabolism. Published online October 31 2012
Johnson JB, Laub DR, John S. The effect on health of alternate day calorie restriction: Eating less and more than needed on alternate days prolongs life (PDF, 64.66Kb). Medical Hypothesis. Published online 2006
Halagappa VKM, Guo Z, Pearson M, et al. Intermittent fasting and caloric restriction ameliorate age-related behavioral deficits in the triple-transgenic mouse model of Alzheimer's disease (PDF, 843.1Kb). Neurobiology of Disease. Published online January 13 2007
Varady KA, Hellerstein MK, et al. Alternate-day fasting and chronic disease prevention: a review of human and animal trials (PDF, 118.6KB). American Journal of Clinical Nutrition. Published online 2007 

Why You Should Exercise

A lot of people need to follow an exercise program, in order to remain healthy.  Below, you'll find several good reasons why you should start exercising now.

1.  Contributes to fat loss

It is well proven from scientific research all over the world that physical exercise contributes to weight loss.  If you burn more calories than you consume through nutrition, you'll lose weight.  When you exercise, you burn more calories than when you don't.  It's really simple - the more you exercise, the more weight or fat you'll lose.

2.  Prevent disease

The chances of developing several various diseases has been proven to decrease when exercising.  These diseases include heart disease, cancer, diabetes, and the stroke.

Around 4 out of 5 deaths caused by heart disease and cancer, are linked to factors that include stress and lack of exercise.  We all know that diabetes increases the chance for heart attacks and strokes. What this shows, is that many of the risk factors and diseases caused by not exercising are working in conjunction to damage your health.  To prevent this from happening, start exercising.

3.  Improving disease

Many severe and minor diseases can be improved or even healed through regular exercise. These even include the diseases listed above.  By following a regular plan, you can also decrease HDL cholesterol levels, decrease triglyceride levels, and decrease your blood pressure as well.

Exercising on a regular basis will also reduce the risk of prostate cancer for men, breast and uterine cancer for women, and much more.  All of this is scientifically proven, which is why you should start exercising today.

4.  Enhance your state of mind

Everyone knows from the many scientific studies that regular exercising will lead to an increased release of endorphins in the body.  These chemicals will fight depression and make you feel happy.  The body releases these endorphins only 12 minutes into the workout.

There is another chemical known as serotonin that is increased during and after a workout. The increased levels of serotonin in the central nervous system is associated with feelings of well being and decreased mental depression. The chemical can also help you sleep better at night.

5.  Enhance your wellness

When you are in great shape and well fit, you'll have more energy and you'll notice that your overall mood is improved.  You will have experienced that you can stretch beyond your own limits and you know that you can do more than you thought possible.

6.  Persistence

Exercising regularly will give you more energy, which can help you be more productive at home and at work.  Exercising can help give your new goals a sense of purpose and give you something to focus on and aim for.  This can help you increase your persistence and prevent you from going off track while you aim for your goal.

7.  Social capabilities

After a workout on a regular basis you can boost your self esteem.  This can help you look better and you'll be more comfortable as well.  Exercise will also help you to become more active and meet new people, which will prevent you from feeling isolated and unsupported.  Exercise will also increase your interests in sex, and can help you to improve your marriage or your partner relationship.



After knowing all of these tips and reasons to exercise, you shouldn't hesitate to get out there and exercise.  You can exercise at home or go out there and join a gym.  There are several different ways that you can exercise, all you have to do is select a few that you like.  Take a little bit of time out of your day and start exercising - you'll feel better than ever before and your body will thank you.

Diets that don't work

Avoid these five types of diets for best weight loss results, experts say.

 

By Kathleen M. Zelman, MPH, RD, LD
WebMD Feature

Medically Reviewed by Dr Rob Hicks http://www.webmd.boots.com/rob-hicks

"Eat what you want, when you want, and watch the pounds disappear!" You've heard of them, maybe even tried them: miraculous-sounding diets that claim to shed kilos with minimal effort. There are hundreds of these quick-fix diets out there, from the grapefruit diet to the detox diet to the "caveman" diet. How do you tell legitimate weight loss plans from diets that don't work?
One reason's it's so hard to tell the difference is that even the worst diets will probably result in weight loss. Don't be fooled into thinking weight loss can be achieved because of some magical food, pill or potion. What causes weight loss is eating fewer calories than you burn. Ridiculous, unbalanced diets cause weight loss because they are basically low-calorie diets.
After a few weeks on an unrealistic diet, dieters usually become frustrated and give up. This leads to feelings of failure that can help send them right back to their unhealthy lifestyles.
" Fad diets not only fail to produce long-term weight loss, they can lead to deprivation, weight gain, and discouragement", says Dr Michelle May, author of Am I Hungry? What to Do When Diets Don't Work. “ In other words, you are often worse off than before you started".

The worst diets ever

Experts have identified five types of diet that are unlikely to produce long-term results for most people. 

1. Diets that focus on only a few foods or food groups (like the cabbage soup diet, grapefruit diet, strict vegan diets, raw food diets, and many low-carb diets).
Beware of any diet that rules out entire food groups.  People need to eat from a variety of food groups to get all the nutrients they need.
Although some restrictive diets do work initially, they fail long term. You can lose weight on diets that focus on single foods, like cabbage soup, but how much cabbage soup can a person eat?  Before long, you grow weary of eating the same foods every day and cravings for favourite foods lead you back to your former eating behaviour.
Keep in mind that all foods can fit into a healthy lifestyle in moderation, even things like bacon and ice cream. And when diets forbid certain foods and dieters envisage a life without their favourite treats, those diets usually fail.

2. "Detox" diets.  (Extreme regimes calling for procedures like liver flushes, bodily cleanses, colonics, or hormone injections).
“All the flushes and cleanses are pure nonsense, unnecessary, and there is no scientific basis for these recommendations", says Dr Pamela Peeke, chief medical correspondent for the Discovery Health channel.  "Your body is well equipped with organs, such as the liver and kidneys, and the immune system, to rid itself of potential toxins and does an excellent job of cleansing itself without needing flushes or cleanses".

3. Diets with "miracle" foods or ingredients (like supplements, fructose water, bitter orange, green tea, or apple cider vinegar).
Dieters are always searching for the food, pill, or potion that will help them lose weight, but unfortunately, there are no such miracle ingredients. In reality, no one single food, or group of foods, eaten together or at a certain time of day has any impact on weight loss.
Be wary of any plan that recommends a shelf full of supplements, enzymes, or potions, these can be expensive and may well offer no benefit.

4. Fasting and very low-calorie diets.
Fasting has been a cultural and religious tradition for centuries, and is fine for a day or so, but fasting for weight loss is counterproductive. When you consume too few calories, your body thinks it is starving and adjusts your metabolism. When you go back to eating normally, your metabolism doesn't readjust and therefore you need fewer calories than before, so you swing between losing weight and putting it back on again, otherwise known as the yo-yo syndrome.
What's worse, weight loss during a fast is usually a combination of fat, fluid, and muscle, but the pounds regained will probably be all fat.  Not convinced yet? Experts say you won't feel good, nor will you have much energy to be physically active while fasting.
What about very low-calorie diets? These may result in impressive weight loss at the beginning but this will slow over time as weight loss averages out.

5. Diets that sound too good to be true.
If it sounds too good to be true, it probably is. Diet plans that claim to have a "secret", that make dramatic statements against respected health authorities, or make recommendations that contradict those of scientific organisations are suspect.

Finding a diet that works

There is no such thing as one size fits all when it comes to diet plans, and it's important to find one that fits your lifestyle. The best diet is one you can safely and realistically stick with for the long term, plain and simple.
It should be flexible enough to fit in with your lifestyle and should encourage healthier eating by focusing on balance, variety and moderation.
In fact, the best "diet" may not be a diet at all.  Instead, think about strategies to satisfy your hunger for fewer calories. Eating more fruit, vegetables, whole grains, and lean protein can help manage your appetite.

Here a two top tips for weight loss.

1. Take stock of what you're doing now and identify your "weakest link". Most people know immediately where they are vulnerable, mid-afternoon snacking, large portions, too much alcohol, a sweet tooth, or snacking all day long.  Try to identify what led to your weight gain and address it. For example, if you overeat because of stress, consider a stress management course. Develop a strategy to address areas where you're vulnerable so you can set yourself up for success.
2. Identify one to three small changes you can make straight away in your diet and exercise habits.  Reassess in a few weeks to see whether your changes are working; then make a few more small changes. Expect to see significant changes in around 12 weeks.

Article Source: http://www.webmd.boots.com

SOURCES:
Dawn Jackson Blatner, RD, LD, spokeswoman, American Dietetic Association.
Dr Michelle May, author, Am I Hungry?What to Do When Diets Don't Work.
Dr David Katz, associate professor, Yale University School of Public Health; author, The Flavor Point Diet.
Dr Pamela Peeke, chief medical correspondent, Discovery Health channel; author, Body for Life for Women.
Andrea Giancoli, MPH, RD, spokeswoman, American Dietetic Association.
Top Ten Red Flags of Junk Science, the Food and Nutrition Science Alliance,1995.

Reviewed on January 17, 2012

© 2009 WebMD, LLC. All rights reserved.

Link Between Weight Gain And Personality Trait Changes

People who gain weight are more likely to give in to temptations but also are more thoughtful about their actions, according to a new study published in Psychological Science, a journal of the Association for Psychological Science.

To understand how fluctuations in body weight might relate to personality changes, psychological scientist Angelina Sutin of the Florida State University College of Medicine and colleagues at the National Institutes of Health (NIH) examined data from two large-scale longitudinal studies of Baltimore residents.

"We know a great deal about how personality traits contribute to weight gain," said Sutin. "What we don't know is whether significant changes in weight are associated with changes in our core personality traits. Weight can be such an emotional issue; we thought that weight gain may lead to long-term changes in psychological functioning."

The studies, NIH's Baltimore Longitudinal Study of Aging (BLSA) and the Baltimore Epidemiologic Catchment Area (ECA) study, included more than 1,900 people in total, of all ages and socioeconomic levels. Data about participants' personality traits and their body weight were collected at two time points separated by nearly a decade. In one study, a clinician measured participants' weight at the two time points; in the other study, the participants reported their weight at baseline and had it measured by a clinician at follow-up.

Sutin and colleagues found that participants who had at least a 10 percent increase in body weight showed an increase in impulsiveness - with a greater tendency to give in to temptations - compared to those whose weight was stable. The data don't reveal whether increased impulsiveness was a cause or an effect of gaining weight, but they do suggest an intimate relationship between a person's physiology and his or her psychology.

In a surprising twist, people who gained weight also reported an increase in deliberation, with a greater tendency to think through their decisions. Deliberation tends to increase for everyone in adulthood, but the increase was almost double for participants who gained weight compared to those whose weight stayed the same.

"If mind and body are intertwined, then if one changes the other should change too," Sutin said. "That's what our findings suggest."

Sutin and colleagues speculate that this increase in deliberation could be the result of negative feedback from family or friends - people are likely to think twice about grabbing a second slice of cake if they feel that everyone is watching them take it.

These findings suggest that even though people who gain weight are more conscious of their decision-making, they may still have difficulty resisting temptations.

"The inability to control cravings may reinforce a vicious cycle that weakens the self-control muscle," the researchers note. "Yielding to temptation today may reduce the ability to resist cravings tomorrow. Thus, individuals who gain weight may have increased risk for additional weight gain through changes in their personality."

Article adapted by Medical News Today http://www.medicalnewstoday.com from original press release.

Co-authors are National Institute on Aging researchers Paul Costa, Wayne Chan, Yuri Milaneschi, Alan Zonderman, Luigi Ferrucci, and Antonio Terracciano, also at Florida State University College of Medicine; and William Eaton of Johns Hopkins Bloomberg School of Public Health.

The research was supported by the Intramural Research Program of the National Institute on Aging and a grant from the National Institute on Drug Abuse.