Page 24 - Hello Philippines February 2016 'B' issue

HEALTH and Lifestyle food
Does the 5:2 intermittent24 www.hello-philippines.com
fasting diet work?
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 think about how fasting will impact on
other than helping people lose weight,
5:2 diet can bring other significant
health benefits, including:
• increased lifespan
• 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 as diabetes, or a history of eating
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 to your GP first to see if it is safe to do be taken in the spirit of us trying to
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
If you are fasting, you may
want to think about how
fasting will impact on your life
during your fasting days.”
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
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
disorders.
Because it is a fairly radical approach
to weight loss, if you are considering
trying IF for yourself, it is wise to speak information provided below should
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
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 that
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 (consuming 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 an 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
February 2016 / Fortnightly – No. 4 • UK & Europe Edition
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 lifespan? There is quite a water maze test).
a wide range of work on the effects of
IF on combating the effects of ageing,
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.
While this makes them ideal subjects
for longevity studies, carrying 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
While the results of these animals
tests are certainly intriguing, animal
have inherent limitations. We can
never be sure that the results will be
applicable in humans.
Is there any evidence that
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
• drinking alcohol in moderation n
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