I have started consuming exclusively Hackerschool soylent (the exact unaltered recipe) 3 days ago, after a transition period of 2 soylent meals a day for about 3 weeks. So far, on all 4 of my exclusively soylent days, I have had a bowel movement. The amount was less than usual; I would guess about 50-70% of what I had eating normal food. This contrasts starkly with other accounts of people trying only soylent (not necessarily hackerschool) for a week. In this article, http://www.fourhourworkweek.com/blog/2013/08/20/soylent/, the guy claims he started having a bowel movement only every other day starting around day 4-6. According to wikipedia - http://en.wikipedia.org/wiki/Human_gastrointestinal_tract, transit through the colon takes up to 50 hours. I would have expected my intestines to be cleared of normal food by now, so I don’t know where this much feces is coming from. I am mildly concerned that my body is not digesting/absorbing all of the soylent (particularly the oat flour). Can others share their experience with this?
That does seem a bit peculiar, though there are a number of variables to consider.
First, how does this compare with the frequency of bowel movements you had before starting soylent? And how does this compare with the frequency of bowel movements you were having during your three-week transition? Though you had a fairly long transition period, I wonder if your body isn’t still “cleaning house” and dumping lots of excess toxins/dead cells/etc. <shrug> Also, you didn’t mention consistency; if it’s particularly soft or even runny, I would take a look at your fiber. Speaking of…
Second, is the amount of insoluble fiber in the recipe perhaps much higher than the amount you were previously consuming? Insoluble fiber functions most observably to bulk up feces and “sweep out” the colon. Remember also that plant material – including oat powder – is typically the main source of insoluble fiber in the human diet.
Then, and I know there’s no objective way of knowing this, the specific bacterial flora in the gut varies significantly from person to person, and this can definitely impact the frequency & consistency & amount of bowel movements. So while most of the soylent community has reported a decrease in both frequency & amount of bowel movements, I haven’t spotted a consensus on “yes, pooping should only happen every [x number] days”.
If you’re concerned about whether or not your body is processing a suitable amount of calories, I would suggest weighing yourself on a fairly regular basis. Any decrease (or a faster decrease than you desire, if you’re looking to lose weight) would indicate that your body is absorbing fewer calories than previously. To address concerns about whether or not your body is absorbing a proper amount of nutrients, pretty much the only way to objectively verify this is to have a complete blood panel done (which is awesome if you have health insurance/accessible health care). Otherwise you’re kind of stuck waiting for deficiency/overdose symptoms to crop up, and that can be a dangerous game to play.