Be-Well Information

I spent about a day trying to answer what appeared to be a simple question. How large (volume or weight) is the digestive system of a typical adult human who is not obese. The best I could come up with is an educated guess.

Why bother? I wanted to roughly calibrate some of the weight loss offers which are flooding my email and showing up all over the internet.

How I got my estimate seems amusing. What I conclude about the meaning for weight loss offers should be useful to readers.

First, my search methods.

I was a physics students back when ARPA-Net was just getting born in some bright brains. My graduate research started with scientific literature in hard copy, plus the mind of a really genius research librarian. There were no generally available computer databases searchable for keywords. In fact, for the first 5 or 10 years of my career in IBM Research and Development, databases were restricted to just the most recent years, and teams were struggling to incorporate information from prior years.

Now, when I want to research on a subject (for an article or to make a purchase, for example), I do what most web surfers do and turn to the Google Search Engine. Unfortunately, my interests often are not satisfied by the easy search results. Fortunately there are some good databases and alternate search engines on the internet, some free, some fee.

Next, how my search proceeded.

I have yet to find any references to the mass of a normal adult human digestive system. Searches using “weight” instead of “mass” mostly turn up the quack weight loss offers that I am trying to exclude.

I did learn common medical names for parts of the digestive system. I even found the mass of the liver (about 3 pounds) and the stomach (about 1/3 pound). However, search for mass of any other part (mouth, tongue, pharynx, esophagus, [liver, stomach,] pancreas, gall bladder, douodenum, jejunum, ileum, cecum, appendix, sigmoid colon, rectum, anus) finds only pathologies such as cancers or stones.

This could be a sign that no one wants to learn about the “normal”, non obese, adult human body. It could mean that we only ask about our bodies when something seems to be wrong. If so, that is very unfortunate, because we should first focus on wellness before concentrating on diseases and injuries.

Search on encyclopedia web sites (wikipedia.org, encarta.msn.com, britannica.com) were not fruitful, nor were government sponsored gateways (such as “U.S. National Institutes of Health” / “National Library of Medicine”). My library’s Health/Medical gateway got me to the Gale Encyclopedia of Science. Search in the Gale Group database for “digestive system” find a great description of what each part does, and the acids and enzymes used, but still not the data on mass.

Method of Estimates

A possibly familiar drawing of the digestive system can be found at http://www.ama-assn.org/ama/pub/physician-resources/patient-education-materials/atlas-of-human-body/digestive-system.shtml. It says that the appendix “has no known function” [in 1998], but recent news suggests the appendix can re inoculate the intestine with digestive flora, in case illness or severe environment stress the system.

Here is a very crude calculation, which might cause the reader to laugh. If any viewer can produce good references for mass data, I will gladly update these calculations. However, I think the target conclusion is still valid.

The frontal drawing is only two dimensional. It shows the stomach taking nearly as much area as the liver, but searches say that the stomach is normally about the size of a fist, expanding with food to about 1.6-1.7 liters or 1.5 quarts. The area of the full intestine looks about 3 times that of the liver, but this ignores the front-to-back dimensions.

If in doubt, make a silly wild guess. Let’s guess that the empty gut is in the ballpark of 4 times the liver in mass, or about 12 pounds. Gut plus liver and stomach, about 15 and 1/3 pounds. Throw in the mouth, tongue, pharynx, and esophagus, and we probably have less than 20 pounds for the entire system, for a non fat adult average American.

Target of Estimates

What is the target of this exercise? Well, I am often bombarded with offers to help me lose 20 lbs in a few days by stripping from my colon, or cleansing my digestive system. I am estimating that my entire digestive system, empty, is less than 20 pounds. I know that I ingest only a few pounds of food per day, dry weight, and about a gallon of liquids, perhaps 8 pounds. For me, the total mass ingested is probably on the order of 11 pounds in 24 hours, but certainly under 20 pounds. I know I am on the low side of “average” 2000 calories in 24 hours.

So how could I realistically lose 20 pounds from my colon? Well, not even by removing my colon.

Of course, if I poisoned myself with laxatives, diuretics, and similar, I could quickly reduce my body mass to the edge of death. In fact, Mussolini used to execute political “dissidents” by forcing them to drink castor oil. Very amusing.

What does this mean for weight loss offers?

I remember the trick question, “Do you know how to quickly get rid of 20 pounds of ugly fat?” The answer was “Cut off your head.” That probably could be said of people who throw money at ridiculous weight loss offers.

Of course, that’s just my opinion. I could be wrong.