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POTENTIAL HEALTH
Benefits
A comprehensive survey by US
newsletter Medical News Today
found advocates of intermittent
fasting ‘say the following benefits can
be achieved’:WEIGHT LOSS
Since the body is unable to draw
its energy from food during fasting,
it dips into glucose that is stored in
the liver and muscles. This begins
around eight hours after the last
meal is consumed. When the stored
glucose has been used up, the body
then begins to burn fat as a source
of energy, which can result in
weight loss.REDUCE CHOLESTEROL
As well as aiding weight loss, Dr
Razeen Mahroof at the University of
Oxford in the UK explains the use
of fat for energy can help preserve
muscle and reduce cholesterol levels.REGENERATE
IMMUNE CELLS
The study by Dr Longo noted above
suggests prolonged fasting may
also be effective for regenerating
immune cells.
‘When you starve, the system tries
to save energy, and one of the things
it can do to save energy is to recycle
a lot of the immune cells that are not
needed, especially those that may be
damaged,’ he explains.
In the study, published in the
journal Stem Cell, his team found
repeated cycles of two-to-four days
without food over a six month period
destroyed the old and damaged
immune cells in mice and generatednew ones.
What is more, the team found
cancer patients who fasted for three
days prior to chemotherapy were
protected against immune system
damage that can be caused by the
treatment, which they attribute to
immune cell regeneration.
‘The good news is that the body
got rid of the parts of the system
that might be damaged or old, the
inefficient parts, during the fasting,’
says Dr Longo. ‘Now, if you start
with a system heavily damaged by
chemotherapy or ageing, fasting
cycles can generate, literally, a new
immune system.’LONGEVITY
Some researchers report years of
animal studies have shown a link
between restriction of calories,
fewer diseases and longer life.
Scientists have studied the
mechanisms behind those benefits
and their translation to humans.
Insulin-like growth factor-1 (IGF-
1) is a hormone linked to certain
diseases that affect lifespan, such as
cancer and type 2 diabetes. Some
experts report eating increases IGF-1
production. Fasting may be a way to
decrease IGF-1 levels, which could
potentially lower the risk of chronic
diseases and extend lifespan.CANCER
Studies have reported that restricting
calories decreases IGF-1 levels, which
results in slower tumour development.
A very small study in people with
cancer found that fasting reduced
some of the side effects of
chemotherapy, including fatigue,
nausea, vomiting and diarrhoea.
Due to potential negative effects,long-term calorie restriction is not
recommended for people with cancer.
Short-term calorie restriction, such
as intermittent fasting, may be an
option for this group of people.NEUROLOGICAL
DISEASES
Intermittent fasting may also impact
cognition. In a study of mice with
genes for Alzheimer’s disease,
intermittent fasting improved
performance on measures of cognitive
decline associated with ageing.BLOOD SUGAR
Some studies have shown that
intermittent fasting improves insulin
sensitivity more than traditional
diets, but others have not found the
same advantage. Researchers have
also reported intermittent fasting and
traditional diets lead to comparable
decreases in haemoglobin A1c.POTENTIAL HEALTH
Risks
According to the UK’s National
Health Service, there are numerous
health risks associated with
intermittent fasting.
People who fast commonly
experience dehydration, largely
because their body is not getting any
fluid from food. If you are used to
having breakfast, lunch, dinner
and snacks in between, fasting periods
can be a major challenge. As such,
fasting can increase stress levels and
disrupt sleep. Dehydration, hunger or
lack of sleep during a fasting period
can also lead to headaches.
Fasting can also cause heartburn;
lack of food leads to a reduction in