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One other exception to the idea that calories in/calories out is just some unchanging closed system is the very simple but highly substantial changes that occur in stool volume depending on your metabolic rate. We’ve talked about how the type of food you eat determines how many calories your digestive system can absorb, but your digestive system can also increase calorie absorption or decrease calorie absorption based on whether it is actively trying to dissipate or hoard energy. states that:

The color, volume and consistency or shape of stool varies from person to person. It is generally accepted that the normal stool is:

  • tan to dark brown in color
  • firm but soft
  • elongated like a sausage
  • passed at least 3 times a week
  • volume of less than 200 ml or 200g per day

It is also typical, if you follow the work of the other Matt Stone, to see stool sing songs full of Christmas cheer.

This topic is of great interest to me, as my own digestive ability, transit time, and stool volume is almost fully controlled by my own rate of metabolism. This has been true for many others as well, and was a major influence in what I wrote in the book 180 Degree Digestion. There are other subtle nuances to changes in diet and changes in food absorption and transit time that may be of great interest to you as well. Hopefully I’ll get into it before this post drags on for too long and I get booted out of the Starbucks I’m currently camped out in while writing this.

For starters, when I say stool volume I mean how much you poop. I first noticed this phenomenon before I even started this here blog. In the summer of 2004 (I think?), I started training for a 50-day solo backpacking trip where I wasn’t going to be resupplying my food at any point throughout the trip. The idea was to go out into the Wilderness for as long as possible without any contact with civilization (anti-social much?). Needless to say I needed to get my legs in shape. My backpack was going to weigh 95 pounds ? well over half my bodyweight to start.

After a couple of short backpacking trips in late June and early July I noticed that I had dropped quite a bit of weight. Like 6-7 pounds. I knew this was trouble. The last thing I wanted to do was go out for my 50 day trip, knowingly going in with insufficient food, leaner than normal. So for the 2-3 weeks before my departure I took it easy on the physical activity and ate as much food as I could stomach. Awwww, my first RRARF!!! ?Sniffle, sniffle.

My normal weight in those days was about a 170 frail, endurance exercise and vegetarian-eating pounds. But I managed to go from the mid-160’s to a sloppy 176 by the time I was to load up and head out. During this time my stool volume went really high. In fact, when I started the trip, I was having 3 large bowel movements every day. If 200 grams is normal, it wasn’t normal for me the first week of that trip! I was passing maybe 500-600 grams in the early going if I had to guess. After years working as a chef, I feel pretty confident estimating amounts of stuff in grams. Plus I was like’so a drug lord in Columbia. You can totally see it right?? Total badass. ?Donde esta mi dinero El Guapo??? Donde!!

What is interesting is that I was eating very little when I first started out. I wasn’t very hungry, and could barely eat the bland oatmeal I had brought or the slimy trout I was reeling in. My later estimates have put me at an average daily calorie intake of 2,600 while on that trip. But all in all my calorie intake per day was fairly consistent. So, if the amount of food and fiber I’m taking in each day was consistent, my stool volume should have been consistent. Right?

Not even close!

The first week I had nice bowel movements an annoying three times per day. You notice these things when you have to poop outside when it’s cold and mosquitos are everywhere. By the second week I was down to two. By the third week I was lucky to have one. Slowly, and steadily ? despite having very consistent food intake and activity levels, I was passing less and less stool. By the 6th week I was only going once every 3 days!!! And these bowel movements, at most, were 50 grams!!! Like a tiny lump of coal!

What was happening was that as my body lost weight and I become increasingly emaciated (and cold, and impotent, and lethargic, and psychotic, and sleep-deprived ? oh, and I peed like 40 times per day), and my body was becoming more and more thrifty ? squeezing every last nugget of energy out of the food I was ingesting instead of just allowing it to pass through freely at a fast rate, largely unabsorbed.

Anyway, this is but another mechanism that changes as your metabolism slows down. Your body absorbs more calories from the food you eat. A sloth, the mammal with the lowest metabolic rate and a basal body temperature of around 93 degrees F, has a 30-day transit time!!! That’s how long food it eats stays in its body.

Likewise, when you start increasing metabolic rate ? and sure you will probably poop more if you are eating more to do this naturally (but that’s not the only factor in the equation), your body stops absorbing calories (and probably metabolic waste as well) so efficiently, and the pipes flush with a jackpot of fecal matter once, twice ? sometimes even three or four times per day. Beauties all of ?em.

So keep this in mind. Especially when it appears that obese people absorb more calories from the food they eat than the lean. Got low metabolism?? But this can be fixed. Or at the very least improved.

And so, what happened when I returned to civilization and ate enough to gain 15 pounds in 10 days or so?? My bowels returned more or less to normal. Although I remained a little chilly for years until I really made the metabolism connection and began to get more aggressive at the dinner table. At which point my bowel movements became the stuff of legend. I hope someday I will be able to have a bowel bout live on pay per view vs. Paul Chek. Finally! There will be shit on tv worth watching!

The other interesting thing I wanted to discuss related to stool volume is what happens when you do eat a lot of indigestible material. Let’s say you eat 30 bananas a day, like the gentleman described here by the 2nd best health blogger in the universe, Anthony Colpo. You are not used to doing this. You are used to eating pancakes and syrup and filet mignon and pizza ? all of which digest and absorb completely with very little residue. Then you eat a high fiber, high FOS, high resistant starch, raw food that digests at a much lower rate. What happens?

Shit happens! Come on. You had to see that one coming.

Eat 30 bananas a day for two weeks though and by the end of the two weeks your body is absorbing all those bananas much better. You are still pooping a lot, but not as much as you were at the start and things are starting to come out more solid and formed. It makes a transition, I believe, by slowing down transit time, and the undigested matter fosters massive bacterial growth (Ray Peat’s reasoning for avoiding bananas ? bacterial growth yields greater serotonin production yields instant death and dismemberment in his theoretical world), which breaks much more of it down into short chain fats.

Okay, now that you have tried that ? switch back over to the pancakes, pizza, and filet mignon. Yep, you aren’t pooping at all now and are plugged up. Even though you weren’t the least bit constipated and had decent stool volume before you ever touched a banana.

Anyway ? not drawing any big conclusions from that in particular. Just saying that a lot of it is transitional. It’s interesting right?? And potentially useful as is any physiological happening. And yes a lot of people who have been eating a coarse fiber-rich diet with lots of raw foods get constipated when they switch to more easily-digestible food. But it is usually temporary, as is having diarrhea once you switch from a processed diet to one that is more unrefined.

Hope you liked this crap.