You’ve probably heard about intermit
tent fasting experts say by reducing your calories two days a week you’ll slim
your waist and reduce your risk of heart disease and type 2 diabetes. Finally,
is this a diet that delivers?
Most diets don’t work, but could this one
be an exception? Intermittent fasting popularly known as the 2-day diet or 5:2
diet has created a storm of interest, not just in the media, but in the science
world too. A diet plan where you simply restrict your intake to 500 calories
(600 for men) a couple of days a week sounds amazing and there’s compelling
evidence that it works.
The evidence
A 2006 study by the Genesis Breast Cancer
Prevention Centre in Manchester found that two-day dieters lost an average of 7.7kg
(6kg of fat) over six months, by eating just 650 calories two days a week and
following a normal diet for the rest of it. People who followed a daily
calorie-restricted diet for six months lost 1.4kg less.
A
diet plan where you simply restrict your intake to 500 calories (600 for men) a
couple of days a week sounds amazing and there’s compelling evidence that it
works.
But it’s the health benefits associated
with intermittent fasting that are most intriguing. ‘Research shows that losing
even a small amount of excess weight – five to 10 per cent of your body weight
can help reduce your risk of diseases such as type 2 diabetes, heart disease
and some cancers,’ says Dr. Michelle Harvie, of the Genesis Breast Cancer
Prevention Centre, and author of The 2 Day Diet (Vermilion, $16.5). But the
process of fasting appears to deliver these health benefits even faster. In
2006, the Centre began testing the theory that restricting calories a few days
per week could reduce the risk of age-related illnesses. ‘Our two-day dieters
had a 25 per cent greater improvement in their insulin function, the root of
many weight-related diseases such as type 2 diabetes, heart disease, some
cancers and possibly dementia,’ says Harvie.
Interest in intermittent fasting was piqued
following Dr. Michael Mosley’s BBC 2 Horizon documentary, Eat, Fast and Live
Longer, last summer. For two, non-consecutive days a week, Mosley limited his
intake to just 600 calories. After three months, Mosley had lost 8.6kg in
weight, and he had also reduced his blood glucose levels from the pre-diabetic
risk category to normal, lowered his LDL ‘bad’ cholesterol levels from
dangerously high to normal and reduced levels of insulin-like growth factor 1
(IGF-1), a marker for cancer risk, in his blood.
So how to explain these benefits? Research
shows that overeating causes levels of the hormones insulin and leptin to soar
in the body, sending a barrage to multiply and grow. Levels of IGF-1 increase
in our blood, cell maintenance is neglected and damaged cells accumulate, which
can lead to cancer, heart disease and diabetes.
‘Our
two-day dieters had a 25 per cent greater improvement in their insulin
function, the root of many weight-related diseases such as type 2 diabetes,
heart disease, some cancers and possibly dementia,’ says Harvie.
But when the body is fasting, it goes into
‘clean-up’ mode. ‘Levels of insulin and lepton fall quickly when we eat less,’
says Harvie. ‘Cells can put more effort into staying in top condition,
repairing damage and removing waste.’ This reduces the risk of disease.
Cruise control
Fasting may also be beneficial for weight
maintenance and better health in the long term. Mosley explains that, having
reached his goal weight, he now fasts one day a week and continues to reap the
health benefits. ‘My weight has stayed steady at 12 stone and my bloods remain
in good shape,’ he says. This was also the case in Harvie’s study. The two-day
dieters kept their weight off for 15 months by fasting once a week, and
maintained lower insulin and cholesterol levels.
But hang on…
Obviously
this is an area of science that’s in its early stages, and as with any diet
plan, intermittent fasting already has its critics.
Obviously this is an area of science that’s
in its early stages, and as with any diet plan, intermittent fasting already
has its critics. ‘The science is young and is largely based on animal studies
so how well the diet can translate to humans is difficult to know,’ says Dale
Rees, registered dietician (mydietaim.com). ‘As the research isn't robust
enough, we need more human studies before this type of diet can be universally
accepted.’ There are also a lot of unanswered questions: is fasting every other
day or just twice a week enough? Should it be a water-only fast or restricted
to 25 per cent of your total calories for one day? Should you fast for 24 hours
or 36? Would a juice fast be better? ‘I have supported clients following an
intermittent fasting plan and it can be quite tough for some,’ says Rees. ‘They
report back that they’ve been snappy and grumpy. While some people can cope
well consuming just 500 calories, others can’t handle the drastic mood changes.
You might feel sluggish and less productive than normal. While the body can
adapt quite well to stresses and strains such as fasting, you would need to be
quite motivated to follow this for the long haul.’ Still, it’s hard to ignore
that intermittent fasting is growing in popularity and people are seeing
results and undeniable health benefits.
