Table of contents:
History of fasting
People around the globe have been practicing periods of voluntary abstention from food and drink since antiquity. There are a lot of different forms and practices of fasting in books on ethnology and religion. Fasting has been used as a form of treatment since ancient Greece. Dr. Hippocrates believed that it was a good way to help sick patients. A number of popular publications and diet recommendations show renewed interest in fasting regimens. By the 21st century, it was still unclear whether fasting was actually helpful for human health. However, in some cases, such as when someone has an acute disease, fasting may help to reduce their appetite. E.H. Dewey believes that many illnesses that affect people are caused by the way they eat. In his book, The True Science of Living, he makes these claims.
Fasting in Religion
Many religions include fasting for spiritual and physical benefits. There is not enough scientific research on these fasts to give an in-depth overview, but here is a brief overview. Fasting can help you focus and stay healthy. 
Fasting in Islam, Ramadan
During Ramadan, Muslims must fast from dawn to dusk. This means they can’t eat or drink anything. Smoking, taking drugs, and having fluids during this time are all forbidden. Depending on the season and the location of the country, fasting can last for 11 to 22 hours. When fasting becomes less frequent, the body might start to change weight because it’s not getting as many calories. Ramadan is a time-restricted feeding schedule that usually lasts for about 29 or 30 days. This means that during Ramadan, people usually eat less than usual. However, there is limited evidence that this type of feeding schedule can lead to weight loss. Ramadan is not an efficient way to lose weight but still, it has many benefits, for example, it reduces the risk of many fatal diseases like cancer.
Fasting in other religions
A study of 448 patients from Utah hospitals found that those who practice routine fasting (29%) have lower weight and lower fasting blood sugar levels, as well as a lower prevalence of diabetes and coronary stenosis. Seventh-day Adventists who emphasize a healthy diet and lifestyle live longer than those who don’t have faith in the Seventh-day Adventist religion. The increase in life expectancy is due to a number of factors, including not smoking, eating a plant-based diet, and exercising regularly. However, it is unknown how many Adventists adhere to a 2 meals per day pattern. This pattern is typically chronic, and sometimes lifelong, which would allow sufficient time to achieve stable changes in physiology. However, the relationship between reduced meal frequency and prolonged nightly fasting with health among Adventists has not been studied. 
Intermittent or alternate day fasting and its types
There is a new type of intervention called intermittent fasting or alternate day fasting. It is a way of eating where you don’t eat any calories on some days, but you can eat normally on other days. Intermittent fasting requires you to fast for different lengths of time, and on different days you can eat whatever you want. The fasting day and the feeding day are different each day. On the fasting day, you can eat 25% of the calories that you would normally eat (about 2000 kJ). On the feeding day, you can eat freely. Intermittent fasting has three following types: 
2. The 5:2 diet
ADF: ADF includes a fast day followed by a feast day. You can eat as much as you want on the feast day. However, on fast days, you’re allowed to drink water and eat only a small amount of food. You can either eat the same amount of food throughout the day, or you can eat a smaller amount of food on a fast day and then have a big feast day dinner.
The 5:2 diet: The 5:2 diet is a modified version of the ADF diet that involves eating five times a week and fasting two days per week. On feast days, you can eat as much as you want. On fast days during the 5:2 diet, you usually consume about 500 to 800 calories, and the fast days can be on consecutive or nonconsecutive days during the week.
TRE: In TRE you have to eat less as compared to ADF and the 5:2 diet. TRE means fasting for a set amount of time each day. This means that during the eating window, you can eat anything you want, but you have to stop eating by a certain time each day. You don’t have to worry about counting calories or watching your food intake during the eating window.
Benefits of fasting to the human body
When you fast, it means not eating for a certain period of time. This can help you lose weight and improve your health in other ways. However, we don’t know yet if fasting is safe and effective for long-term use. Some researchers are concerned about the possible effects on aging, health, and disease processes. Some researchers are studying the different effects of fasting on the body. Short-term fasting, such as intermittent fasting (IF), has some temporary effects, while prolonged fasting (more than 8 days) has more long-term effects. The following are the benefits of fasting:
Helps in weight control, prevents type 2 diabetes, and reduces the risk of metabolic syndrome
There are a lot of different treatments being developed to help people with obesity and MetS problems, but the most efficient natural remedy seems to be fasting. A metabolic syndrome is a group of abnormalities that includes being overweight, having high blood pressure, and having low levels of good cholesterol. It is also linked to other health problems.
Induces metabolism of fatty acids to ketones
When there is not enough sugar in the body, the body turns to other sources of energy. These sources come from the breakdown of fats in the body. This can happen when you are fasting or not drinking enough fluids. This process induced by fasting is known as ketogenesis, a mechanism that regulates whole-body glucose metabolism.
Rectifies & prevents dyslipidemia
A study regarding the effect of fasting on lipid metabolism concluded that fasting resulted in a reduction in total cholesterol and triglycerides along with a rise in levels of HDL-C, which had beneficial effects on lipid profile post-fasting period.
Improves blood pressure
Fasting is related to the reduction of systolic blood pressure and diastolic blood pressure in individuals who are healthy or have hypertension or diabetes. Weight and total body water have no effect on this mechanism.
Prevents oxidative stress
Oxidative stress is the imbalance between the synthesis and detoxification of reactive oxygen species in cells. According to research, fasting reduced oxidative stress based on MDA (malondialdehyde) and GSH (Glutathione) levels in the heart and brain, respectively. 
Benefits of fasting for society
Fasting gives us a feeling that we should help poor and needy people who don’t get enough food to eat. Government must encourage this process to motivate us all. Furthermore, fasting can decrease the ratio of obese and overweight individuals’ population.
What to eat after breaking fast?
You should eat gentle foods to break the fast. These foods will not put much burden on your stomach and will get digested earlier. Some of these foods include vegetables, smoothies, soups, dates, salat, and nutritious foods
Difference between fasting and caloric restriction
Calorie restriction generally means a less intake of calories, it doesn’t cause malnutrition because it doesn’t reduce the total number of calories. It has been found to help reduce body weight and increase lifespan in many different species. In overweight people, short-term calorie restriction (6 months) has been shown to improve multiple cardiovascular risk factors, insulin sensitivity, and mitochondrial function. While fasting or intermittent fasting is when you consume little or no calories for a short period of time and then avoid eating for a longer period of time. This is different from regular eating where you eat all the time.
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