Frequently Asked Questions About Fasting

As animals, we all need food and essential nutrients. Nutrients and vitamins are important in order for our body to function properly. Fasting and starvation are widely discussed topics because everyone wants to know how fasting and starvation effect our body. Fasting has become a widely spread trend that some people incorporate in their everyday diet. Starvation is different because most of the time starvation isn’t by choice. If we were to fast and starve what would our body do? Would everything in our body be affected? Would our metabolism be affected? Would we… die? In this paper, you will find out the answers to all those questions and more.

This paper will explore what fasting and starvation are, the effects that fasting and starvation can cause, and the advantages/disadvantages of them both.

Starvation is defined as the post-absorptive state which means that all of the food is digested and there is no glucose coming in from the gut.

Glucose plays a very important role in our bodies cycles and systems. For example; the brain uses roughly 120g/day of glucose. Also, parts of kidney, skin, and red blood cells cannot use anything else but glucose, unlike other tissues that can switch to fatty acids to use as an alternative fuel [6]. Glucose is extremely important for the liver because of risk of hypoglycemia. “During the first few hours of starvation, the liver tissues are using glucose which causes the blood glucose concentration to decline [6].” In order for the liver to prevent hypoglycemia, the liver releases glucose into the blood stream which allows the glucose levels in the blood to remain constant.

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Extended period of starvation is extremely dangerous. “After only 2-3 days of starvation, your body can lose roughly 50-100g protein/day. Even though ketone bodies help slow the loss of protein by inhibiting proteolysis (the breaking down of proteins) the body will still lose protein [6]”. Proteins are lost from all tissues of the body which can lead to damage of the body. Most people believe that what kills us during starvation is the lack of food/nutrients but what ultimately kills us is the lack of protein.

Now, fasting is a bit different from starvation because there are some cultures/traditions where fasting is something religious and is done by choice. There is a newer trend going around in the world that is called Intermittent fasting, which once again, is something that people choose to partake in. Most people believe that fasting is beneficial to our health and scientists over at John Hopkins have researched fasting and they believe that it is extremely beneficial. “Scientists at John Hopkins say that too many calories in our diet can have negative effects on the brain [5].” According to Matt Mattson, who is a professor of neuroscience at John Hopkins, cutting your energy intake by fasting several days a week could potentially help prevent neurodegenerative diseases such as Alzheimer’s and Parkinson’s [5]. Mattson and other scientists also believe that fasting can improve memory and mood.

How does fasting prevent these neurodegenerative diseases? “In laboratory experiments performed by Mattson and his colleagues, found that intermittent fasting (limiting caloric intake at least two days a week) can help improve neural connections in the hippocampus while also protecting neurons against the accumulation of amyloid plaques (aggregates of misfolded proteins that form in the spaces between nerve cells) which is associated with Alzheimer’s disease [5].” Every time we eat glucose it is stored in your liver as glycogen. Once the glycogen is used up, the body starts burning fats, which are then converted to ketone bodies. Ketones are good for our body and they enhance overall brain health, but if people eat three times a day with snacks in between our body doesn’t have the time to deplete the glycogen storage, so the body can’t produce more ketones.

There are 4 types of fasting; complete alternate day fasting, modified fasting regimens, time restricted feeding, and religious fasting [4]. Complete alternate day fasting involves alternating fasting days with eating days. “Modified fasting regimen allows for the consumption of 20-25% of energy needs on scheduled fasting days [4].” Time restricted feeding is eating ad libitum (feeding on demand or when hungry) energy intake within a certain time frame. “Religious fasting are fasting regimens that are taken for religious or spiritual purpose [4].” Religious fasting is very common among several different cultures.

Fasting can provide rapid weight loss if done correctly, but for some people fasting diets are difficult to sustain for long periods of time. Some find it difficult because they have to go without food from anywhere from hours to days and then when they do eat, it’s a challenge to not overeat [1]. Fasting works by making one eat fewer calories, which results in weight loss. There are a variety of fasting diets such as the 16/8, the 5:2, and the eat-stop-eat diets. “The 16/8 diet involves skipping breakfast and restricting eating for only 8 hours of the day and then fast for 16 hours [1].” The 5:2 diet involves eating 500-600 calories 2 days out of the week and then eating normally during the other 5 days. Lastly, the eat-stop-eat diet involved fasting for 24 hours once or twice a week. Although fasting can be difficult because there is a risk of undereating which could put the body into starvation mode which is extremely bad for one’s health.

Starvation mode is defined as a metabolic response to the body from being deprived of food for long periods of time. “This may occur during periods of famine or economic depression, when using a fad diet, or when suffering from anorexia nervosa [3].” There are physiologically symptoms of being in starvation mode such as fatigue, anemia, heart failure, depression, anxiety, and etc. Decreasing your caloric intake will reduce the amount of nutrients and energy in your body which gives the common symptom of fatigue. Fatigue is extremely common in starvation mode because without energy the body will not function properly because energy is needed for nearly every process in the body. “During starvation mode, the body also breaks down muscles to be used as fuel so it can keep the heart and other organs functioning [3].” Another symptom of being in starvation mode is a lack of vitamins and minerals, which a deficiency in them can lead to anemia, diarrhea, rashes, edema, and heart failure.

During starvation mode testosterone and estrogen levels decrease so sexual drive decreases as well. “A common symptom of being in starvation mode in females is a possibility of irregular menstruation or absence of menstruation [3].” There are a few more symptoms of starvation mode that will be talked about which involve food obsession and weight regain. Food obsession occurs because the body needs food and nutrients so the mind will think and/or talk about food without even realizing it. “People with anorexia nervosa may also spend time watching cooking shows, looking at recipes, or even shopping for food [3].” Weight regain can occur because a reduction in the intake of food can lead to a reduced metabolic rate. When the body’s metabolic rate decreases, weight gain increases.

Starvation for short or long periods of time can cause starvation ketoacidosis (a high anion gap metabolic acidosis due to an excessive blood concentration of ketone bodies), which occurs when hepatic glycogen storages are exhausted so the liver produces ketones, which provide an energy substrate for peripheral tissues [2]. “Ketoacidosis can appear as soon as overnight after a fasting period but for severe starvation ketoacidosis, it requires roughly 5 to 14 days of starvation to reach maximal severity [2].” Ketoacidosis includes a relative or absolute insulin deficiency. Having no insulin in the body is extremely dangerous because without the hormone insulin, the body can no longer move glucose from the blood into the cells which causes high blood glucose levels.

Fasting and starvation are similar in that they both involve withstanding from foods, but they’re very different because starvation is complete withdrawal from food (mainly involuntary) whereas fasting can be withdrawal from food anywhere from hours to days (mainly voluntary). Starvation is extremely dangerous and can cause several problems in the body and should not be practiced. Starvation after only a few days has little to no harm to the body permanently, but over longer periods of time it can cause severe complications to your health such as protein loss, glucose loss, hypoglycemia, and death. Starvation is not a way to lose weight, in fact studies have shown that starvation over a long period of time can actually slow down the body’s metabolism which will make the body gain weight.

Fasting on the other hand can be extremely beneficial when done correctly, such as fasting for 2 days and then eating the other days. When practiced safely and correctly, fasting can help improve memory, mood, ketone bodies, and can help prevent against neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. Fasting can also help promote weight loss and that’s why the majority of people who fast do it to lose weight fast. Knowing the facts and the effects of starvation and fasting, one can see that fasting is extremely beneficial, whereas starvation is extremely harmful.

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Frequently Asked Questions About Fasting. (2022, Jul 01). Retrieved from

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