Intermittent Fasting

Dr. Atif Arif MD
Updated January 4th 2021
December 15th 2020

Many people swear to have lost pounds of fat with intermittent fasting

while other claim it helped them build muscle after their results were
stagnating for some time already. So what is intermittent fasting
exactly and how does it work? It must be clear that intermittent
fasting (IF) is not a diet. A diet is a predetermined plan of what you
eat on a day while IF means you eat during certain times of the day
only. IF is therefore more similar to an eating pattern, just as
eating 3 or 6 meals a day is. The IF eating pattern consists of a
short period where you eat, followed by a longer period where you
don’t eat at all (fast). There are many different eating patterns
possible with IF, but the most popular are fasting for 24 hours twice
a week (5–2 pattern) or fasting for a period of 16 hours a day (16–8
fasting). A combination of these two patterns is also possible.

How does intermittent fasting work?

Basic instinct tells you that only eating for a short period of time
and not eating for a longer period of time would probably lead to
eating fewer calories which would result in a caloric deficit (burning
more calories than you eat) and weight loss. While this is true, the
real idea behind IF is different.

During the period of time that you don’t eat your body will use
glycogen stored in the liver and muscles as fuel. It will take about 6
to 8 hours to completely deplete these stores after which fats are
used as the primary source of energy. By fasting for more than 8 hours
per day you will therefore burn stored fat resulting in weight loss.

But what about the time that you do eat, don’t you gain back the same
amount of fat? You would think this is true if you approach the body
as a something simple, but due to complex processes involving hormones
the reality is different. By not eating for longer periods of time
your body becomes more sensitive for insulin which is a hormone that
helps cells absorb glucose from the blood. The more sensitive your
body is to insulin, the less insulin it will produce, and the harder
it will be to store energy in fat cells.

The surplus of available energy can now be used more efficiently, for
example for recovery and building muscle. This, together with an
increase in human growth hormone production that is promoted by the
fasting, will result in a better recovery and an increase in muscles.

Intermittent fasting, if applied correctly, can help you in several ways:

Burn stored fat as a source of energy
Increase the production of human growth hormone
Increase sensitivity to insulin
Make it harder for your body to store energy as fat
More efficient use of nutrients resulting in an increase of muscle
mass and better recovery

The story is all positive so far for intermittent fasting, but if
applied in an incorrect way it can do more harm than good. In part 2
we will explore some of the problems with IF.

https://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-11-98
https://www.sciencedirect.com/science/article/pii/S1568163716302513