Thursday, March 13, 2008

Why am I so hungry?

If there's one thing I've noticed about Eat Stop Eat, it's how it makes me very aware of what does and doesn't make me hungry.

Oddly enough, when I'm fasting, I rarely get hungry, but when I'm eating and I miss a meal, I get hungry (and grumpy).

I've received a number of emails on the topic of intermittent fasting and hunger, and I think I've figured out my own personal theory on the connection.

In fact, I received an email this morning from my friend Justin Owings ( about his experiences with Eat Stop Eat, and I think between the two of us our experiences with fasting and hunger have been identical..


I've been implementing about two fasts a week for around a month now and
have managed to lose about 10 pounds of weight and 2 - 3% body fat.

What I'm curious about is how fasting has seemed so easy for me. I don't
get heavy hunger pangs while fasting -- when I do notice my stomach, its
usually for a minute or two and then it completely goes away. Does this
mean that my body has adjusted? I originally just assumed that my body had
switched to fat burning for energy, and since there's still a solid amount
of fat energy to use up, it doesn't send me heavy "hunger" signals.

Just curious if you had any thoughts on this.


Hey Justin,

Great question and great timing, I was just discussing this exact same
phenomenon with some colleagues.

We believe that it's not as much your body that is adjusting to the fasts
as it is your mind.

For instance, on a non-fasting day, if I was planning to eat at noon, but
got caught in meetings until 2, I would feel like I was "starving". Yet on
fasting days, I absolutely do not notice that I have not eaten. Typically,
I don't get hungry at all, except for a few hungry pangs that may last for
a minute tops.

I've come to the conclusions that this has a lot to do with expectation of
eating, and the
biochemical reactions that this expectation causes.

So I think what you are experiencing is a better control over your minds
influence on your body. I think that because fasting allows you to take
breaks from constantly eating, it teaches you better control over the
perceptions of being "hungry".

In the end, even hunger may be a case of "mind over matter".


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Murray said...

It is a good question, and I've noticed something similar: although all my food cravings have diminished since I started Eat-Stop-Eat-style fasting, hunger is certainly more of an issue on eating days.

I wonder if this might be related to an apparent paradox noted by Taubes, among others: traditional calorie-restricted (that is, portion- or nutrient-restricted) diets have a very high failure and relapse rate, largely because they induce hunger cravings that, in the long term, are unendurable for many people. At the same time, researchers studying fasted people commonly observe that they do not suffer from high levels of hunger or a fixation on food.

(From a discussion on Michael Eades's blog, it appears that many people who follow every-day fasting routines with an eating window every evening DO suffer from food cravings and lethargy

This seems odd: what is fasting but calorie or nutrient restriction on an extended scale? But on one regimen hunger screams, while on the other it whispers. I'd venture (hardly originally) that eating makes you hungry: people on calorie-restricted diets don't eat enough to sate their hunger, but they do eat enough to raise insulin levels, which causes nutrients to be shuttled into the fat cells, which leads to a demand for more circulating nutrients, which causes hunger. Fasted people, on the other hand, are operating on low insulin levels, a net transfer of nutrients out of fat and into the blood, and thus low levels of hunger (at least until the nutrient flow out of the fat cells abates). Does this sound right?

Murray said...

Whoops. I was going to leave the parenthetical on Eades out, but it found its way in anyway.

What I was going to say is the daily fasting routines seem (from the anecdotes on Eades's blog) to cause cravings and lethargy similar to those experienced on calorie-restricted diets. (Eades himself used DF as a way to gorge on carbs, and didn't like the results.) I'm not sure what's going on, but DF seems to have an entirely different character to IF.

Brad Pilon said...

Hi Murray,

Looks like you've had a lot of the same experiences that Justin and I have had.

I see where you are going with your points, however I'm still prone to thinking that this is much more of an emotional / psychological phenomena then it is food effecting true hunger.

It is kind of like quiting cold turkey (albeit only for 24 hours) as opposed to taking a little bit of your addiction at at time, hoping to cut back.


John B said...

I tend to agree with Brad on this topic. I've done fasts of 24,36 and 48 hours...besides the odd hunger pang that lasts a minute or two each of these lengths of fasting are remarkably easy to get through. In fact when I go past about the 30 hour mark I feel as though I could continue indefinitely.

However on an "eat" day the thought of food and knowing that I am free to eat brings food much more to the forefront of my conciousness and it consumes more of my thoughts. Whereas on a fast day food simply never enters my stream of thoughts as I have already assigned it zero possibility of being eaten until my fast is over.

I in this case it seems like we are actually doing a psychological trick "Out of mind out of sight"...instead of "out of sight out of mind"...I can be exposed to my favorite foods on a fast day and have no feelings of wanting to eat them...but on an 'eat' day if I am exposed to foods I like I will have a much greater urge to eat them.

John B

Sara said...

Hi Brad,
I just wanted to let you know that I've been writing a review of my Eat-Stop-Eat experiences over at my blog. I thought I'd just make a quick summary, but now it's turned into a three part saga. It could just be that I waffle on... ;)

Juan said...

I have noticed the same thing. Although lately, I have lost hunger feelings during my non-fasting days too. Sometimes I have to force myself to eat some just to avoid going on a fasted stay 2 days in a row.

Murray said...

I certainly agree that there's a significant emotional/psychological factor to not being hungry on fasting days. Like today, for me: 13.5 hours without food and I feel great, not hungry at all. Yesterday at this time I was wanting that grapefruit pretty badly...

However, I do believe there's also a strong physiological component to lack of appetite while fasting. In any case, here's an interesting entry on Mark Sisson's blog, which further implies that one-meal-a-day daily fasting routines (as opposed to truly intermittent fasting like ESE) may not be all that good for you.

Carrie said...

Very interesting, something I'll definitely have to muse on. I was thinking the other day about a similar thing though- how I can be not hungry or thinking about food, and be just fine, but then suddenly something trips the trigger and it's all I can do to keep from eating something.

And then there are other days when I just can't keep myself out of the food at all, or days when I could just go without completely.


john said...

Hi Murray,

I've reviewed the research papers on Mark Sissons blog. I've left a comment on his blog reviewing the accuracy of the research cited. I present a different perspective than Mark on the 3 vs 1 meal per day. If you analyze the papers closely you'll find that there is basically no difference with their results. Both papers have serious methodological limitations and the end results. The major finding from the papers that seemed to be overlooked was that the 1 meal per day people lost weight when the 3 mealers didn't.