Ramadan is the holiest month in the Islamic calendar and Muslims fast during this month.

Meaning: Derived from “RAMADHA”, literally means “intense heat”. The possible reasons for this meaning:
1. When the Islamic months were enforced the month of fasting coincided with the summer months of intense heat.

2. The second reason which has been mentioned is that due to fasting the temperature within the stomach increases, again the element of heat is a factor behind the actual naming of RAMADAN.

3. It has also been said that “RAMADHAA” is one of the names of Allah Ta’aalaa. If that is the case then the month has acquired the name due to the fact that Allah Ta’aalaa burns away accumulated sins and eliminates then from the list of unlawful deeds. Once again the burning sins cannonades “HEAT”. However. it should be acknowledged that this reasoning is not wholly reliable.
Blessings:
Hadhrat Salmaan (R.A) reports that on the last day of Sha’baan the Messenger of Allah Ta’aalaa addressed then and said, “Oh people, there comes before you now a great month, a most blessed month in which lies a night more greater in virtue than 1,000 months; (LAYLATUL-QADR). It is a month in which each day should be observed by fasting, this has been made obligatory by the Almighty Allah.”

Islamic Refrences

On the authority of Al-Miqdaam ibn Maadiy-Karib who said: I heard the Messenger of Allah saying:

“No human ever filled a vessel worse than the stomach. Sufficient for any son of Adam are some morsels to keep his back straight. But if it must be, then one third for his food, one third for his drink and one third for his breath.”

(Ahmad, At-Tirmidhi, An-Nasaa’I, Ibn Majah )

Who Is Excused From Fasting In Islam

Praise be to Allaah.
One of the ways in which Allaah has made things easy for His slaves is that He has only enjoined fasting upon those who are able to do it, and He has excused those who are unable to fast for a legitimate shar’i reason. The legitimate reasons for which one may be excused from fasting are as follows:

1 – Sickness

Sickness means everything that means that a person is not healthy.

Ibn Qudaamah said: the scholars are agreed that it is permissible for the sick person not to fast in general. The basis of that is the aayah in which Allaah says (interpretation of the meaning):

“but if any of you is ill or on a journey, the same number (should be made up) from other days”[al-Baqarah 2:184]

It was narrated that Salamah ibn al-Akwa’ (may Allaah be pleased with him) said: “When this aayah was revealed – ‘And as for those who can fast with difficulty, (e.g. an old man), they have (a choice either to fast or) to feed a Miskeen (poor person) (for every day)’ [al-Baqarah 2:184 – interpretation of the meaning] – those who wanted not to fast could do that, and pay the fidyah (i.e., feed one poor person for each day). That remained the case until the following aayah was revealed, i.e., the verse:

‘And as for those who can fast with difficulty, (e.g. an old man), they have (a choice either to fast or) to feed a Miskeen (poor person) (for every day)’

[al-Baqarah 2:185 – interpretation of the meaning] – so it abrogated it.”

The sick person who fears that fasting may make his sickness worse or that it will slow down his recovery or damage a part of his body, has the option of not fasting, and indeed it is Sunnah for him not to fast and it is makrooh for him to complete his fast, because that may lead to his death. So he has to be cautious and protect himself. Moreover, if the sick person is very ill, that makes it permissible for him not to fast. But if a healthy person fears difficulty or tiredness, it is not permissible for him to break his fast, if all that happens to him when he fasts is that he becomes tired.

2 – Travelling

In order for traveling to result in a concession excusing one from fasting, the following conditions must be met:

a- The journey must be long enough that prayers may be shortened.

b- The traveler must not intend to settle in the place to which he travels.

c- His journey must not be for any sinful purpose, rather it should be for a sound purpose, according to the majority of scholars. That is because being allowed not to fast is a concession and relief that the sinner does not deserve on his journey, because the purpose of his journey is to commit sin – such as one who travels in order to commit banditry, for example.

Cancellation of the concession for traveling:

This concession of traveling is cancelled by two things:

(i) When the traveler returns home and enters his hometown, which is the place where he resides.

(ii) When the traveler decides to stay indefinitely, or for a lengthy period in one place, and the place is fit for settling in. Thus he becomes a resident (or non-traveller), so he should pray his prayers in full and not break his fast in Ramadaan, because the rulings on travel no longer apply to him.

3 – Pregnancy and breastfeeding

The fuqaha’ are agreed that pregnant and breastfeeding women may break their fast in Ramadaan, on the condition that they think there is a risk that they or their children may become ill or more ill, or be harmed or may die. The evidence for this concession in their case is the aayah (interpretation of the meaning:

“and whoever is ill or on a journey, the same number [of days which one did not observe Sawm (fasts) must be made up] from other days”[al-Baqarah 2:185]

This does not refer to merely being sick, for the sick person who will not be harmed by fasting is not allowed to break the fast; here sickness is mentioned as a metaphor for any situation where fasting when sick may cause harm. This is what is meant by sickness here. That may be the case in pregnancy and when breastfeeding, so these two cases are included in the concession of breaking the fast. The evidence that women in these cases are allowed not to fast is the hadeeth of Anas ibn Maalik al-Ka’bi (may Allaah be pleased with him), who said that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Allaah has relieved the traveler of fasting and half of prayer, and He has relieved the pregnant and breastfeeding woman of fasting.”

4 – Senility and old age

Senility and old age refers to one who is old and has lost his strength, or who is approaching death, so that every day he becomes weaker, until he dies, or who is suffering from a terminal or incurable illness and has no hope of recovery. The evidence that it is prescribed for such people not to fast is the aayah (interpretation of the meaning):

“And as for those who can fast with difficulty, (e.g. an old man), they have (a choice either to fast or) to feed a Miskeen (poor person) (for every day)”[al-Baqarah 2:184]

Ibn ‘Abbaas (may Allaah be pleased with him) said that this aayah has not been abrogated, and it applies to old men and old women who cannot fast, so for each day they should feed one poor person.

5 – Intense hunger and thirst

If a person is overtaken by intense hunger or unbearable thirst, then he should break his fast and eat just as much as he needs to ward off that hunger, then he should refrain from eating for the rest of the day, and make up that fast later on.

The scholars added to intense hunger and thirst the fear of weakness when meeting the enemy, or fearing or expecting an attack, such as when one is surrounded. So if a fighter knows for sure or thinks it most likely that there will be fighting because he is facing the enemy, and he fears that fasting may make him weak when fighting, and he is not traveling, then he may break his fast before fighting.

6 – Compulsion

Compulsion means one person forcing another to do something or not to do something against his will, by means of threats.

Effects Of Ramadan On Health

Metabolisem

Tehran University of Medical Sciences, Iran evaluated weight, body mass index (BMI), glucose, triglyceride (TG), cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), and very low density lipoprotein (VLDL), before and after Ramadan.
The changes of metabolic profile and weight during Ramadan fasting. 
Body weight and BMI both decreased during Ramadan fasting in both genders. Glucose and HDL decreased and LDL increased significantly during fasting in Ramadan, but there was no significant change in total cholesterol, TG and VLDL. We did not find any association between TG, cholesterol, LDL, VLDL, HDL and the following variables: sex, body weight changes, and two or three instances of meals before Ramadan. Triglyceride level also increased in students with normal BMI while it decreased in overweight subjects.
This study indicated that Ramadan fasting led to a decrease in glucose and weight. Although there was a significant reduction in meal frequency, a significant increase in LDL and decrease in HDL was noted during Ramadan. It seems that the effect of Ramadan fasting on serum lipid levels may be closely related to the nutritional diet or biochemical response to starvation.
Type II Diabetes
One more evaluation was done To evaluate the effects of fasting on anthropometric indices and carbohydrate and lipid metabolism in patients with type II diabetes.
Diabetes clinic, Shariati Hospital, Tehran, Iran during Ramadan 1419 (winter 1998-99)
Fifty-seven volunteers with type II diabetes underwent anthropometric and biochemical evaluation before and on the 14th and 28th days of Ramadan. Biochemical markers were measured by standard laboratory methods and anthropometric indices by WHO criteria. Statistical analysis was done by ANOVA for repeated measurements and Friedman’s two-way ANOVA using SPSSv6 software.
RESULTS:
Daily cholesterol intake increased in all subjects (p<0.03). Body mass index increased in women (p<0.03), but BMI and waist-hip ratio both decreased in men (p<0.01). Blood pressure, fasting blood glucose and serum fructosamine did not change during the study. Plasma insulin (p<0.05), C-peptide (p<0.01) and insulin resistance (p<0.01) decreased only in men. Total and LDL cholesterol increased significantly in all subjects during the study.
CONCLUSION:
Ramadan fasting does not alter carbohydrate metabolism or tissue insulin sensitivity in patients with type II diabetes given appropriate dietary education and rescheduling of oral hypoglycaemic medication. Lipid profile is unfavourably altered due to changes in both diet and biochemical response to starvation.
Ramadan fasting on physical performance and metabolic, hormonal, and inflammatory parameters in middle-distance runners.
The Ramadan fasting (RF) period is associated with changes in sleep habits and increased sleepiness, which may affect physical performance in athletes, and may induce metabolic, hormonal, and inflammatory disturbances. In 8 middle-distance athletes (25.0 +/- 1.3 years), a maximal aerobic velocity (MAV) test was performed 5 days before RF (day -5), and on days 7 and 21 of RF. The same days, saliva samples were collected to determine cortisol and testosterone concentrations before and after the MAV test. Blood samples were collected before RF (P1), at the end of RF (P2), and 1 week post RF (P3). Plasma levels of interleukin (IL)-6, a mediator of sleepiness and energy availability, were determined. We also evaluated changes in metabolic and hormonal parameters, mood state, and nutritional and sleep profiles. During RF, mean body mass and body fat did not statistically change. Compared with day -5, MAV values decreased at days 7 and 21 (p < 0.05, respectively), while testosterone/cortisol ratio values did not change significantly. Nocturnal sleep time and energy intake were lower at day 21 than before RF (day 0/P1) (p < 0.05). At the end of RF (day 31), the fatigue score on the Profile of Mood States questionnaire was increased (p < 0.001). For P2 vs. P1, IL-6 was increased (1.19 +/- 0.25 vs. 0.51 +/- 0.13 pg.mL-1; p < 0.05), melatonin levels were decreased (p < 0.05), and adrenalin and noradrenalin were increased (p < 0.01 and p < 0.001, respectively). At 7 days post RF, all parameters recovered to pre-RF values. In conclusion, RF is accompanied by significant metabolic, hormonal, and inflammatory changes. Sleep disturbances, energy deficiency, and fatigue during RF may decrease physical performance in Muslim athletes who maintain training. Reduction of work load and (or) daytime napping may represent adequate strategies to counteract RF effects for Muslim athletes.
Conclusion

Our study findings support that beneficial effect of Ramadan fasting in elderly patients with cardiovascular risk factors were observed in early post-fasting period including an increase of HDL-C levels and better control of glycaemia. In contrast, in the fasting period there is a risk that renal function decrease with a simultaneous increase of glycaemia which could be deleterious for diabetic patients.