The Physiological Changes That Occur During A Fast
For many people, the key question regarding fasting is whether it is good or
bad for your health. The answer to this requires a quick overview of what
happens inside the body during fasting: the physiology of fasting.
The changes that occur in the body in response to fasting depend on the length
of the continuous fast. Technically the body enters into a fasting state eight
hours or so after the last meal, when the gut ?nishes absorption of nutrients
from the food. In the normal state, body glucose, which is stored in the liver
and muscles, is the body's main source of energy. During a fast, this store of
glucose is used up ?rst to provide energy. Later in the fast, once the stores
of glucose run out, fat becomes the next store source of energy for the body.
Small quantities of glucose are also ‘manufactured' through other mechanisms
in the liver.
Only with a prolonged fast of many days to weeks does the body eventually turn
to protein for energy. This is the technical description of what is commonly
known as ‘starvation', and it is clearly unhealthy. It involves protein being
released from the breakdown of muscle, which is why people who starve look
emaciated and become very weak.
As the Ramadan fast only extends from dawn till dusk, there is ample
opportunity to replenish energy stores at pre-dawn and dusk meals. This
provides a progressive, gentle transition from using glucose to fat as the
main source of energy, and prevents the breakdown of muscle for protein. The
use of fat for energy aids weight loss, preserving the muscles, and in the
long run reduces your cholesterol levels. In addition, weight loss results in
better control of diabetes and reduces blood pressure.
A detoxi?cation process also seems to occur, as any toxins stored in the
body's fat are dissolved and removed from the body. After a few days of the
fast, higher levels of certain hormones appear in the blood (endorphins),
resulting in a better level of alertness and an overall feeling of general
Balanced food and ?uid intake is important between fasts. The kidney is very
ef?cient at maintaining the body's water and salts, such as sodium and
However, these can be lost through sweating. To prevent muscle breakdown,
meals must contain adequate levels of ‘energy food', such as carbohydrates and
Hence, a balanced diet with adequate quantities of nutrients, salts and water
Source: Ramadan Health Guide