The Hunger Returns: Fasting

I had intended to do a 30-hr fast beginning at noon, yesterday, with both a hearty breakfast and lunch prior. It didn't work out that way.

I wasn't really hungry in the early morning (never am, anymore), so I didn't fix anything until about 9am. I hadn't had bacon & eggs in a while (really), so I fixed five strips and fried up two eggs in my newly acquired lard. I had intended to add in some red grapes, but apparently Bea absconded with those for her packed lunch. Oh, well. Then came noon; then 1pm, and still not hungry. Oh, well; again. I guess my fast begins at 9:15am.

By around 4pm I was getting hungry and didn't really relish going until bedtime. What to do? I decided on walking the five minutes over to the gym for some self-experimentation.

Let's back up. Some will recall around the first of the year when I began experimenting with intermittent fasting, the idea being that we are evolutionarily adapted to going long periods without food, and that when we do, we turn to burning fat in place of muscle glycogen (stored carbohydrate). The body also releases growth hormone in response to prolonged hunger, the purpose being a perfectly logical evolutionary adaptation: GH serves to protect lean muscle tissue, while also opening up the floodgates of fat burning (low levels of insulin also get the fat moving the other direction — meaning high levels of insulin keep fat in place, or store it).

Now, follow the logic. Stored glycogen (from all those grains you're told are so wonderful) lasts a few hours, maybe a day, at low activity. Go out running? You've got about 2 hours, tops. It's what long-distance runners call "hitting the wall." First one that punches through (to sustained fat burning), wins. Now, how long can you go with zero carbohydrate? Indefinitely; your body can synthesize the tiny bit of essential glucose you need from gluconeogenesis. How long can you go without eating anything? Months, and it's because you have stored fat and lean tissue (protein). That's true starvation, of course, but the point is that carbohydrate is not required to sustain life. It was entirely depleated on fast-day 1. The fact: we are adapted — indeed it's perfectly natural — to go without food for a day or so now and then. We're adapted, because: that was the nature of real life in most environments under which we evolved. Today, in recognition of that fact, some of us go hungry now and then on purpose. There are various reasons for it, including losing fat, gene expression (some forms of gene expression lay dormant until triggered), healing (What do animals do when sick? They don't know it, but they are turning full resources to healing. Acquisition and digestion of food takes a lot of energy.), and "cleansing." Scare quote on that last one to poke fun at all the foolish cleansers out there who fall for all those marketing scams for products to ingest to "cleanse." There's actually a biological function, and it's called autophagy, or self eating. Art has a post on it. You want to cleanse? At the cellular level, perhaps? Fast.

Alright, I took the time to revisit the background on fasting to get to one point, before I get to the final point. Last evening I was reading a book by a well-known fitness guru who generally does good work, but the diet recommendations are off, significantly ("avoid processed foods" is there, however, and that's worth at least 50%). Anyway, same old saw: eat six small meals, always eat a hearty breakfast, and NEVER (he used caps) skip a meal under any circumstances. And, and… never do an intense workout without eating. Why? Going hypoglycemic (low blood sugar).

Right. Can you imagine Thor going into diabetic coma while running down prey as though his life depended on it (it just might have), because he'd been really unlucky on the hunt and hadn't eaten for a few days; and after all, the invention of the fridge was about 250,000 years away?

I just hate that sort of modern ignorance. You should note the emphasis.

Anyway, I and others thoroughly disproved that notion some time ago. Go take a look, and follow the links to others who had similar results. Long story short: if I measure my blood glucose well into a fast, say 20-24 hours, it's going to be in the high 70s, low 80s. Then I go work out with very heavy weights, very intensely, for 30 minutes, with little rest in-between exercises. At the end, my blood glucose will be in the low 100s. How's that? I didn't drink any "energy" crap, and I still haven't eaten anything. Well, you can be a fool to modern ignorance, but I'll have no part.

Now for the next experiment, which I mentioned back at the beginning. I went down to the gym for a simple sauna, steam bath, Jacuzzi, and then the cold pool. As I said: I was hungry and wanted some enjoyable activity to get my mind off it. I spent about 10 minutes or so in the sauna, just a few in the steam room (now I'm really pouring sweat), then into the Jacuzzi. The reward for all that torture (it's really stressful, for me) is the cold dip, which they keep around 50 degrees or so. I go in after the workouts because it's like an energy reset button. I've worked myself up from about 30 seconds to now bouts of 5 minutes or so. That's what I did yesterday, but even longer. I stayed in until I had a pretty violent shiver going, then I got out, took a cold shower, and went home.

Before I did, I weighed myself at 199 (after the sweating). I remained a bit chilled for quite a while, but then noticed something: no hunger. Not at all. Then, 11pm rolls around and I hit the sack. Slept great for eight hours, got up for the customary 3.5 mile walk, and I'm still not hungry. Not at all. I go home, got ready to shower, and stepped on the scale for a big shocker: 194. I had dropped 5 pounds in a matter of hours. And, it's now 1:30pm (when I began this post), 28-hours into the fast, and just now the hunger begins to return. I've got to suspect the ice-cold water to the point of a pretty good shiver for both the unusual lack of hunger and the extreme weight loss. I'll have to see if I can duplicate on the next fast.

Now, before anyone gets all excited, I will surely gain some of that weight back once I begin feeding tonight, a couple hours after my workout at 4pm (the workout will shut down hunger 5 minutes in). However, since I'm still in fat-loss mode, the idea is to keep my food intake normal and not try to make up for the deficit. Maybe I'll get 2 pounds net out of it, and I'd be really happy with that.

I woke up feeling exceptionally strong and taught (very common when I fast). While there may have been some lean tissue in that mix of loss, I doubt very much. Recently, I have been increasing weight at the gym almost every week.

Wow. This turned out to be far longer than I'd planned. But I've been feeling exceptionally exceptional, lately, so look for more as the days roll by.

Later: I went to the gym for my workout this afternoon, 31 hours in and had a great workout. After the sauna, steam, hot tub and cold dip, I was at 4.5 pounds of loss from the night before, not 5. My home scale hovers between 4-5 pounds lighter than the weight & balance scale at the gym, so the 5 was an estimate. 4.5 is the real number.

Also, the workout was one of my highest energy ever. I stayed in the cold dip (55 degrees or so) for eight minutes and didn't develop any shiver as I did the night before at only about 6 minutes. One speculation is that by then I'd reached a sort of homeostasis in the context of the fast and had steady energy, plus some from the intense workout.

I'm going to see if I can duplicate this on my next fast.

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  1. Erik on August 29, 2008 at 02:33

    Great read. Thanks!

  2. Richard Nikoley on August 29, 2008 at 10:00


    Saw it and linked it in the last entry (How to Cook).

  3. Bill on August 29, 2008 at 04:31

    Hey Richard,
    great post,also have you seen the tv interview Mark Sisson did,it's on his site he really drives home it's all about the insulin and carbs that make you fat.I some time wonder if it would be better to go high fat and protien and no carb's fo a low insulin response like you said we don't need carbs really.

  4. MB on August 29, 2008 at 14:26

    Great post! very thought provoking

  5. Matt on August 29, 2008 at 20:19

    Hi Richard,

    I've been an EvFit lurker here since about January, and experimenting on myself with EvFit eating and altering my training just a little bit.

    I hadn't thought about checking blood glucose before and after exercise at the end of a fast. After reading this post, I checked mine after a 24-hour fast which included four and a half hours of indoor rock climbing near the of the fast. Here's another data point: my blood glucose was 94 almost two hours after I finished climbing.

    (Blatant plug for one of my favorite climbing gyms: Planet Rock)

    I've lost 10 pounds since January, and I wasn't even trying to lose weight since I was already pretty trim. I was just trying to eat healthier.

    Thanks for distilling all the great info!

  6. Richard Nikoley on September 3, 2008 at 11:29


    Absolutely! And, if you don't have those sorts of facilities, you can make your own steam room by running the shower of hot, then your own cold dip in the bathtub.

    I recommend about 60 deg F, 15.5 C.

    BTW, love your Paleo Kitchen blog and am gald you stopped by.

  7. Naomi on September 3, 2008 at 10:31

    Hello Richard,

    I'm a bit late commenting on this, but I'll do it anyway ;) Just wanted to let you know that the only fast over 16 hours that I do is spend in the 'sauna'. I think that might be a dutch thing so I'll explain briefly what exactly that is;
    A spa like place, 100 Celsius cabins, steam rooms, jacuzzi, a swimming pool, a very very cold dipping pool, lot's of lying around in the sun or near a fireplace.
    Going there early afternoon (after pre-fast of 12 hours or so), staying till midnight and falling asleep straight away when coming home is absolutely the most perfect fast for me.

    It makes me feel on top of the world :)
    Just thought I'd let you know you're not the only one benefiting from a little cold. More people should try it.

  8. JLL on October 1, 2009 at 14:50

    So the sauna is torture for you, haha. You know us Finns consider the sauna a relaxing place! Plus, I think the saunas here are much hotter than the ones you find elsewhere. I haven't noticed a hunger-relieving effect from saunas, however. Haven't tried the cold showers, though.

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