The Scientific Effects Of Fasting On The Body

They also saw that those mice were 45% less likely to develop cancer and their insulin levels were 90% lower. These mice were still able to retain their mental ability and beat the control animals in two kinds of memory tests.

In another study, short-term fasting was as effective as chemotherapeutic agents in delaying the progression of tumors in mice. This study concluded, “That multiple cycles of fasting promote differential stress sensitization in a wide range of tumors and could potentially replace or augment the efficacy of certain chemotherapy drugs in the treatment of various cancers.”


Here is a great video that explores the difference of when you reduce your caloric intake, versus cutting out food entirely.

In 1944, a study called the Minnesota Starvation Experiment was conducted to see the effects of caloric restriction due to the amount of people suffering from starvation as a result of the ongoing World War and to see what kind of aid should be provided to as a relief effort. The physical and psychological conditions of the men were extreme, from being very co

ld to completely obsessing about food. They only thought about food and exhibited neurotic behaviors like hoarding cookbooks, and even eating rotten vegetables out of desperation.

Dr. Jason Fund, a Toronto physician explains that reducing your caloric intake actually results in more difficulty losing weight, making it easier to lose more lean muscle mass. Those who do this are generally in a constant state of hunger. However, while fasting, you are only hungry for the first few days during peak periods (usually the times when you normally have breakfast, lunch, and dinner), before the sensation completely disappears and your energy levels stabilize.

This is due to the amount of Ghrelin in the body. Ghrelin, also known as the hunger hormone is responsible for the feeling of hunger and weight gain. Generally, ghrelin levels spike in the morning, at lunch, then dinner time because our bodies have been programmed to expect food at that time. A study conducted at Aarhus University Hospital in Denmark found that in the first 84 hours of fasting, ghrelin levels continually decreased. Typically after the first 3 days, hunger disappears altogether.

What also happens after the first several days is that our bodies go into a state called ketosis. This is one of the most important factors in fasting. Ketosis is when your metabolism switches to using mostly fat for energy, rather than carbohydrates and glucose.

This is why the subjects in the Minnesota experiment had very little energy and found themselves becoming very sluggish. They were eating just enough to keep their bodies out of ketosis, so they were unable to use their body fat for energy. When you restrict calories, your insulin levels drop drastically and your metabolism slows down, leaving you feeling tired and hungry.

On the other hand, when you cut out food entirely, your metabolism actually speeds up, and allows you to maintain a normal level of energy in your body!



Fasting can be an amazing practice, however, for many, it can be difficult to get started. Mark Mattson recommends trying one of two possible ways to begin fasting that’s gentle for most people who want to give it a try. The first system is called the 5:2 diet, which limits your caloric intake to 500 calories, two days a week.

We typically eat around 2,000 calories a day, so this is a substantial reduction. This would equate to 1000 calories a week, but splitting it up into two meals gives your body time in between to reach ketosis. As opposed to splitting it up daily and eating 145 calories or so a day, which as we discussed above would result in exhaustion and much more hunger pains.

Drinking water fasting other way is what we’re calling “window eating”, which is the purposeful timing of your meals so that you eat in an eight-hour window of time, giving your body enough time to exhaust its levels of glycogen and start producing ketones. You can extend this practice a bit longer, and give yourself a small window of time to eat every day, reducing your daily meal count from 3+ meals to 1 meal over several hours, and then be fasting roughly between 18 to 22 hours every day.

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