Is Fasting Good For You?

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People do short fasts and long fasts for many reasons. Some people claim that it helps to reduce the risk of developing many diseases and also that it helps to clean out toxins from the body. Some people also do it for spiritual and religious reasons. I’ve had quite a lot of experience with short fasts of about one to three days, but never more than this. Is there any benefit going beyond three days?

In 2007, I experimented with fasting by consuming most of my calories early in the day and creating a cut-off point where I wouldn’t eat beyond a certain time. So for example, I would wake up by 7 am and consume all my calories for the day by 2 pm.

I experienced many things during this time: I remember feeling a lot more alert, and I could fall asleep faster and sleep better. Aside from the noises in my stomach due to not eating — which usually came on at the most inconvenient times  — the long fasts were pretty easy for me because at the time I had so many things that distracted me from the hunger I felt during the day.

I’ve always found it to be quite easy to experiment with different dietary patterns, so it wasn’t too much trouble for me. Even when I was consuming 1550 Calories per day for several years, I didn’t find it too difficult.

After about 5 years, I decided to increase my calorie intake so that I could increase my BMI a little. I felt that having such a low BMI was too risky at that time.

I did this fasting experiment where I would stop eating early in the day for about a year and then returned to my normal pattern of eating.

Using fasting to maintain a low-calorie diet

In the last few years, I have settled into fasting one day a week. This not only gives my body a rest from digestion, but it helps lower the average calorie intake across the week, in case I’ve eaten too much on any particular day during the week. It averages out to my target calorie intake.

In animal studies, it’s the total calorie intake that matters when it comes to being able to down aging. It’s not about when the calories were eaten. I find this method very effective, easy to do, and it makes it even easier to maintain a low-calorie diet.

Benefits of Fasting

As for the health benefits of fasting, there are many!

You do not have to fast for a crazy amount of time to enjoy the benefits that fasting can bring to you. When a person fasts, their body releases certain hormones such as ghrelin, which stimulates appetite and has many beneficial effects on the body such as:

  • Increased motivation
  • Reduced anxiety and depression
  • Protective against neurodegenerative diseases
  • Enhances learning and memory

When you fast you also increase the production of a protein called Brain-derived neurotrophic factor (BDNF). This protein is also increased when a person is on a calorie restricted diet or is exercising. The beneficial effects of BDNF include:

  • Enhanced learning and memory
  • Protection against neurodegeneration diseases; Alzheimer’s and Parkinson’s
  • Increased neurogenesis

In 2012, there was an excellent documentary called Eat, Fast, and Live Longer. Michael Mosley investigated research behind calorie restriction, fasting, and aging.

He traveled around the United States to speak to researchers who are at the cutting-edge of aging research to find out which is the best way to reduce the risk of disease and possibly slow down aging.

During the show, he spoke to Mark Mattson, who is an expert in his field. He explained how beneficial fasting is for the brain and how well it delays the onset of Alzheimer’s disease in mice that are destined to get it at an early age.

To speed up the onset of Alzheimer’s disease, the researchers put Fructose in their drinking water. The mice on the high sugar diet who were not on the fasting diet developed the disease earlier than the mice that were fasted!

Although fasting is greatly beneficial to our health, there is no need to take it too far. One or two days is more than sufficient for you to get some benefits from doing it.

Prolonged fasting can also be dangerous to your health. In one study conducted on rats, they showed that every-other-day fasting caused diastolic dysfunction. where the heart became stiff and did not relax properly. They also showed that fasting caused a reduction in systolic pumping capacity.

So, if you’re thinking about doing a fasting diet, my advice would be to be careful with prolonged fasts. One day is totally fine and will not hurt you and there is no need for 1-week fasts.

See more about fasting here and here.


1. Mattson MP. Energy intake, meal frequency, and health: a neurobiological perspective. Annu Rev Nutr. 2005;25:237-60
2. Protecting new neurons reduces depression caused by stress.

3. Meyer RM, Burgos-Robles A, Liu E, Correia SS, Goosens KA (October 2013). “A ghrelin-growth hormone axis drives stress-induced vulnerability to enhanced fear”. Mol. Psychiatry. PMID 24126924

4. Diano S, Farr SA, Benoit SC, McNay EC, da Silva I, Horvath B, Gaskin FS, Nonaka N, Jaeger LB, Banks WA, Morley JE, Pinto S, Sherwin RS, Xu L, Yamada KA, Sleeman MW, Tschöp MH, Horvath TL (March 2006). “Ghrelin controls hippocampal spine synapse density and memory performance”. Nat. Neurosci. 9 (3): 381–8. doi:10.1038/nn1656. PMID 16491079

5. Wenzhen Duan*, Zhihong Guo*, Haiyang Jiang*, Melvin Ware†, Xiao-Jiang Li‡, and Mark P. Mattson. Dietary restriction normalizes glucose metabolism and BDNF levels, slows disease progression, and increases survival in huntingtin mutant mice
6. Lee J, Duan W, Mattson MP. Evidence that brain-derived neurotrophic factor is required for basal neurogenesis and mediates, in part, the enhancement of neurogenesis by dietary restriction in the hippocampus of adult mice. J Neurochem. 2002 Sep;82(6):1367-75.

7. Ahmet I1, Wan R, Mattson MP, Lakatta EG, Talan MI. Chronic alternate-day fasting results in reduced diastolic compliance and diminished systolic reserve in rats. J Card Fail. 2010 Oct;16(10):843-53. doi: 10.1016/j.cardfail.2010.05.007. Epub 2010 Jul 1.

Article reviewed and updated: February 2019.

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1 Comment

  • In this article you speak of an eating schedule that you adopted in 2007 where you woke up at 7am and consumed all of your calories by 2pm and creating a long overnight fast. According to everything I have heard and read on eating to the Circadian Rhythm and practicing Calorie Restrivtion, this seems the ideal way to eat.
    When I have tried this, I lost too much weight and did not sleep as well. Have you experimented with this eating pattern recently? I am curious to learn more about this pattern of eating as this is the ideal I am aspiring to!!!

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