I have been studying this again lately. I have done a lot of fasting over the years. I know I feel wonderful when I do fast. It is just difficult to stick with. Usually a day is all I can stick to but I notice even when I eat less I feel better. I have sarcoidosis and the strange things that go with that. I really don't know how to explain it but fasting can be euphoric. I was so glad to see this post.

I don't have time to fully leap into the fray here, but do address one small issue, I think short-term fasts for spiritual/religious purposes are different than fasting for the specific purpose of weight loss.

Originally Posted by petlover:
I was trying to remain respectable, but I feel that maybe I am not getting the same respect in return. I can respect research articles, but not all things that work in mice work in people (leptin), and also it takes A LOT of research for something to be taught/in a textbook, although I am always eager to learn about new research, I simply urge people to pick up a textbook and find out for themselves - or possibly ask a doctor why they all advise so strongly against it.

Good luck on your journey.

I meant no disrespect petlover, I apologise if you feel that way. :(

And I whole heartedly agree, adequate research should be done and you should consult a doctor before embarking on a fast as per mandalinn82's suggestion.
I believe this site is very supportive, before creating this account and posting here I've been lurking for a while and really got a lot of inspiration from the success stories. I hope you don't judge the entire site based on my post, it is an anomaly all things considered.
Most of the problems associated with hypoglycemia occur from insulin issues. Specifically, I believe you are referring to neuroglycopenia. However, glycerol is a byproduct of the break up of fat and can be used in gluconeogenesis, which produces glucose and is one of the fuels for the brain during a fast. During a fast, the brain is the sole reliever of all glucose produced this way. Therefore, technically, a person fasting is still providing glucose to the brain (though it doesn't provide 100% of the energy required). In a healthy individual, none of this is really a concern.

As previously stated, I have read numerous texts and journal articles in preparation for my first fast. What was listed in the second post was simply what I could remember easily or find by retracing my steps when I did the initial research. I would like to reiterate netwellness.org/question.cfm/37350.htm as it has an active professor and registered RD stating what I have already. I never meant, nor want, to advocate fasting as an end all be all cure. Nor do I mean to anger anyone. I simply want to introduce it in a scientific way free of the fear mongering that is ever present when the subject is breached.

Ooh boy, I don't know how to say this without sounding argumentative, but I don't believe that you succeded in your attempt "to introduce [fasting] in a scientific way."

Instead, it came off as bashing the blanket statement "fasting is bad," while pushing forth, an equally blanket statement "fasting is great."


Your enthusiasm for fasting is very obvious in your post (and I understand that if it's working for you, that type of enthusiasm can be difficult to mute).

There is as much (if not more) "anti-fasting" research as there is "pro-fasting" research, so an assertion that all the anti-fasting information is myth, bias and fear-mongering, and all the pro-fasting information is scientific, factual, and unbiased is really the same problem - just two sides of the same coin. I'm overstating a bit, because you do seem to be trying to acknowledge some of the "cons" of fasting, but it's very obvious that you're being pulled more by the pro-fasting data than the data leading to other conclusions. You find the pro-fasting research more compelling, I find the anti-fasting research more compelling. I suspect that our personal experience with fasting has more to do with our positions than objective reality. There is an abundance of data that can be used to support either - which risks a person is willing and not willing to take will affect their opinion.

I've been "studying" weight loss methods for nearly 39 years (since I was 5), and my experience with fasting has not been positive - though while I was doing so, I thought it was amazingly positive, it was only afterward that I saw the negative effects as well as the positve - and for me the negative effects outweighed the positive.


In high school I lost much of my weight essentially through fasting (often eating only on weekends). I was being supervised by my pediatrician with monthly appointments. He didn't know the extent of my fasting, but he knew enough to encourage me to reverse my thinking and eat more during the week, and less on weekends (so that I'd have more energy during the school week). In my freshman and sophomore at college, I also attempted weight loss with fasting (without medical supervision).


The biggest downfall to fasting, in my opinion is not in the health risks, it's in the unhealthy relationship with food that it can trigger. Being "good" means not eating, eating becomes "bad."

As for the cons that you mention, that were mild an manageable you say, in your experience. However, they were quite severe in mine.

-Blackouts or dizziness (which can be caused by low blood sugar as well as by low blood pressure). I frequently felt like fainting, and did pass out several times while fasting. Losing consciousness is not a minor inconvenience, it's a serious symptom that can be dangerous. Thankfully, I did not have a car, and was not driving any of the times I was fasting.

Muscle pains or headaches. I experienced this severely. Again, there's no scientific basis for the "detox" theory. There's been found no significant difference between pre-fasting and post-fasting levels of any known toxins that would account for the muscle pains and headaches. Although low blood sugar explains the fatigue and headaches quite well. In fact, the low-blood sugar headache is one I've become very familiar with when I reduce carbs too severely (I follow a reduced, but moderately low-carb diet - about 100g of carbs per day on average).

Pain and tissue damage release endorphins. The fasting "high" has been attributed to those endorphins (and unlike the toxins, these endorphins do show up in lab tests during fasting).

Hunger. I believe (my untested theory) that learning to ignore hunger has potentially long-lasting negative consequences. In my experience, I strongly believe that crash dieting and fasting, that is learning to ignore and override hunger has left me with a very impaired ability to recognize "true" hunger. I ignored it for so many years, I don't recognize it anymore when I feel it.

For me, fasting and modified fasts triggered a compulsive eating disorder. On non-fast days I ate until my stomach hurt. When I started eating, I couldn't stop - it was if I now only had two eating speeds "off" and "gorge". That kind of binging has both chronic and acute risks.

When I stopped fasting, and vowed off all crash diets, my binge disorder "disappeared," reason enough to be wary of fasting, in my opinion. There's a good deal of research support suggesting that it's not unusual for fasts and modified fasts to trigger binge eating - even in non-overweight subjects.


And my biggest argument against the unpleasant side effects of fasting is that the unpleasant side effects are entirely avoidable. Weight loss can be done without fasting, and can largely be done without hunger at all. When I fasted, I had to devote quite a deal of thought and effort into the fast and managing the side effects of the fasting. The 80 lbs I've lost "this time" have been slow, but largely effortless (I deliberately chose effortless so that I wouldn't have to sacrifice most of my life on the alter of weight loss - and am willing to pay the cost ofr a slower weight loss as a result).

Fasting may work for some with relatively few drawbacks, but it is entirely NOT universally benign. The risks are potentially severe enough that anyone wanting to attempt fasting as a regular weight loss/maintenance tool, really needs to talk to their doctor (and ideally a registered dietitian).

What an amazing summary kaplods!

I can respect the research that you have done (not just jumping into it blindly), but my main point is that many others may read your advice and not do their own extensive research. As I have said, I can at least respect the pro-fasting research and anecdotal evidence, but the anti-fasting support is what is taught in schools and followed by medical profesionals - there aren't so much myths as exaggerations.

Anyways, just mainly if you are even considering this method, please consult a medical professional or endocrinologist or something of the sort.

Also, I am referring to fasting in terms of weightloss - if you are fasting for religion/etc. then I don't mean to judge a belief system.

Originally Posted by petlover:
I can respect the research that you have done (not just jumping into it blindly), but my main point is that many others may read your advice and not do their own extensive research.

I think I might have left an erroneou impressions - I did not research fasting until AFTER my experience with it. I very much DID jump into it blindly (with disastrous results). I only learned of the risks and pitfals AFTER my experience with it.

I would hope that nothing I posted would encourage anyone to make the mistake that I did. I would not encourage anyone to attempt serious long-term fasting, even WITH a doctor's supervision. I think the risks and negative side effects just don't make it a good choice for most people.

I don't see religious fasts in the same light for several reasons. Not the least of which, is that religious fasts are generally temporary, short-term fasts, with a very limited scope and duration, so in general I suspect they are safer. However, many religions who encourage fasting, also allow dispensations for people whose health might be jeapardized by fasting - the elderly, children, pregnant women, and people who because of health or disability would be at greater risk from fasting.

Originally Posted by petlover:
Anyways, just mainly if you are even considering this method, please consult a medical professional or endocrinologist or something of the sort.

I would actually warn people to be even more cautious than this. I think getting an "ok" from a doctor just isn't sufficient. Generally doctors are not well educated in the field of nutrition, so I think both a physician AND a dietician should be consulted and that the person should have monthly appointments with their medical/dietetic support team.

There have been many reported deaths from fasting and modified fasting - even under medical supervision. Most recently was a woman (I think this past summer) who was fasting and exercising to lose weight for her wedding. She was seeing her doctor monthly WITH blood draws. She was young and in excellent health, and she died suddenly of heart failure.

Contributing to her death was low sodium levels from the intense exercise (electrolyte imbalance) and muscle damage from the fasting.

Being under medical supervision does not make the risks disappear, it only increases the odds of (and doesn't guarantee) problems being caught in time to treat them.


Because the risks and possible consequences are SO severe, I would strongly encourage people to err on the side of caution. Weight loss can be done at a slow or even moderately fast pace, and "getting it off as fast as possible at all costs," just is not the best way. There are many health risks and possible complications associated with extremely rapid weight loss that just outway the benefits for most people.

It's just socially acceptable to take the "all costs" approach to weight loss because fat is seen as so evil that death is seen as better than spending one more day fat than necessary.

How are you doing Norska? It would be interesting to see how this works out for you.