Intermittent Fasting - Complete Guide (A Scientific Approach)
Would you skip breakfast if it gave you the chance to
live longer?
I
skipped breakfast this morning, skipped my 11am snack and have been doing so
for the last three years.
My
daily eating consists of two meals, the first is eaten at 12pm and the last
just before 8pm. I then go 16 hours before eating again. It is an approach to
eating called intermittent fasting.
Within
my first 6 months of intermittent fasting I decreased my body fat percentage by
2%, increased lean muscle mass and decreased my 5k time from 24 minutes to 19.
I trained the same amount, I ate less, yet I got faster, stronger and leaner.
Intermittent fasting: Healthy Fats you'll Include in your Diet to Reduce
How is this possible?
For
most of history, humans haven’t been
eating three meals per day with additional snacks in between. Rather, people
evolved to survive and prosper though long periods of food shortage. The
advancement of farming and food-on-demand is only a recent prospect and it has
drastically changed our eating habits. We now spend most of our time in front
of computers and eat as we please. Eating in this way is not what our bodies
are adapted to.
A 1982 study monitoring showed
that a five day fast managed to increase Human Growth Hormone (HGH) by 300%. As
fat starts to replace glucose as the main energy source for the body the need
to burn carbs decreases and the need to catabolise protein is reduced. Another study showed a 5-fold
increase in HGH production in response to a 2 day fast.
Sugars
and fats are the body’s primary sources of energy. When the body has depleted
its glucose stores the body will adjust by using fat. This is the way we
survived when food sources were not as consistent. A couple of thousand years
ago it is highly likely that humans would have to go without food for a few
days, multiple times per year. Our bodies are adapted to food consumption based
on this inconsistency.
What is Intermittent Fasting?
The
three most common forms of intermittent fasting are:
·
Alternate-day fasting — Eating one meal that contains around 25% of
daily calorie needs 3 times per week. e.g. Monday-Wednesday-Friday. On
non-fasting days, caloric intake is unrestricted.
·
Whole-day fasting — Similar to alternate-day fasting but
restricted to one to two days per week. Complete fasting or consuming up to 25%
of daily caloric intake on 1/2 days per week with no calorie restrictions on
the other 5/6 days. The 5:2 diet is an example of this. It encourages 2 days of
fasting with limited calorie intake and 5 days where calorie intake is not
tracked.
·
Time-restricted feeding — Encourages feeding within a fixed
window each day typically between 8–10 hours. Eg Eating only between 12–8pm and
fasting the rest of the day.
The
method I refer to here is time-restricted feeding, or less abstractly known as
intermittent fasting. It separates itself from “diet plans” in that it
sustainable for long periods without feeling hungry. It is more of an
adjustment in how many hours you eat for. You can eat the foods you want, you
just eat two meals instead of three.
Why do People Fast Intermittently?
Intermittent
fasting is an schedule adjustment technique that is most commonly used to lose
weight. However, this is not the only health benefit. It is possible to gain
muscle mass whilst reducing body fat percentage.
Many
people will struggle to get enough calories in in an 8 hour window and feel
full eating less than their normal daily calories.
How Does Intermittent Fasting Work?
Intermittent
fasting makes intuitive sense. When we eat food, it is broken down in our
digestive systems and turns up as a variety of molecules in our blood. Our
bodies use the sugar from broken down carbohydrates for energy, a process that
occurs rapidly for refines carbs and sugars. When we do not use all of the
energy provided by food we store it as fat. Sugar cannot enter our cells on its
own, our bodies produce insulin to bring the sugar into our fat cells for
storage.
In
between meals our insulin levels decrease and fat cells can release the sugar
they have been storing. We lose fat when our insulin levels go down and this is
the basis of intermittent fasting — to allow our bodies enter a state where
they are using fat as our fuel source meaning we lose weight.
We
start to burn fat around 12 hours after eating, this is when we enter the
fasted state. For this reason it is rare for people without actively
intermittently fasting. It is also why people who start fasting lose fat
without changing their diet. Intermittent fasting puts the body in a state of
fat burning that you would never normally reach.
Cooking
is a passion of mine. Cooking one less meal per day is still something I
appreciate. Anything that makes life simpler or reduces decision making,
especially in the mornings, is greatly appreciated.
Benefits of Intermittent Fasting
1.
Fat Loss
When insulin levels drop you start to use fat as a fuel source instead of
sugars. Fat that is stored around you body will be used for energy.
2.
Reduced Cancer Risk
Studies on animals suggest that intermittent fasting can help reduce cancer
risk. These studies indicate that diets that restrict calories could push back
the onset of tumors.
Being
overweight is a risk factor for multiple different cancers so the weight loss
associated with intermittant fasting could be the reason for the reduced cancer
risk that these studies hint at.
3.
Brain Health
Research into mice have shown signs that fasting can lead to improved brain
health. The link could be associated with reduced inflammation and showed that
mice who fasted intermittently has a higher capacity for learning and memory
that those with unlimited access to food. Studies have even shown links to
reduced risk of Alzheimer’s and Parkinson’s disease.
4.
Much Easier Than Dieting
Most diets don’t work because they are too restrictive or take too long to
implement. Following a juicing diet where you are peeling fruit and vegetables
three times per day and getting very few calories from them is both
inconvenient and restrictive.
I
enjoy the ease of intermittent fasting. Not eating in the morning takes a
little getting used to but your body will adapt quickly. I find morning most
productive when I just have a black coffee to kick start the day. I quickly got
used starting eating at midday. It really frees up mornings to focus on a
workout and my most important tasks.
Examples of Intermittent Fasting
FAQ
How
long should I fast for to receive the benefits associated?
Your
body will start burning fat after around 12 hours. For benefits associated with
fat loss 14–16 hours is recommended.
When
doing a 16:8 fast can I eat whatever I want?
Losing
weight is a simple matter of energy in vs. energy out. Weight loss occurs when
the body is in a caloric deficit. Intermittent fasting aids weight loss by
decreasing the window for eating, making it difficult to graze all day.
Is
intermittent fasting just used for weight loss..? Or can I build muscle at the
same time?
While
many people use intermittent fasting a vehicle to lose weight, building muscle
is very possible. People will often lose weight while fasting and think they
have also gained muscle. You see, because they look more muscly, you would be
inclined to think you gained muscle. What has happened is losing fat has made
your muscle look more defined. Muscle gain occurs when you have you have a
caloric surplus meaning muscle that gets broken down during exercise can be
rebuilt in a larger, stronger form. Caloric surplus is entirely possible during
16:8 fasting and I have gains a lot of muscle while fasting.
When
should I exercise when using the 16:8 method?
I
exercise every morning as soon as I wake up. This is part of a habit ladder i
have built to ensure mornings are as productive as possible. Exercising and
fasting can be a little tricky as it will make you more hungry. So if you’re
still getting used to fasting it can make lasting the whole 16 hours more
difficult. To begin with, try exercising during the feed period, then move to
exercising just before breaking your fast so you can eat straight after working
out. This way you will be occupied in the last hour of your fast and as soon as
you finish your workout and your body needs nutrients you can eat. Exercising
in the the feed or fast periods are both fine, it’s just a matter of personal
preference.
Will
intermittent fasting slow down my metabolism?
We
are commonly told that eating little and often is the best method for weight
loss. The logic goes something like, “consuming food increases metabolism so
eating more food will increase my metabolism more”. Whilst true, it is also
true that the metabolic increase is proportional to the number of calories
consumed so whether you consume your food in large meals or lots or little
ones, the metabolic effect will be the same.
The positive side effects of Intermittent Fasting are phenomenal for a lot of people, but as with all advice involving health you should contact your medical practitioner before starting.
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