A recent journal article, published online here, describes and intersection between two clinical conditions that I always take very seriously: increased abdominal size and small intestinal bacterial overgrowth. Of course, as in any purely observational study, these findings tell us really nothing about how things work: they simply raise a question that merits further study.
Increased abdominal size is relative. It really doesn’t matter if your waist exceeds the “standards” for waist size unless it also exceeds more than half your height.
Mini-rant: two things drive me crazy in standard WebMD type articles about overweight. First that they use BMI at all, a worthless measurement that just compares height to weight with utter disregard as to whether that weight comes from fat or muscle. A beautifully muscled weight lifting woman I met said her doctor told her she was obese: I didn’t see an ounce of fat on her. Meanwhile, someone with a protruding belly but thin arms and legs will pass the BMI test. See what I mean, crazy, right? My second rant is touted as an improvement on BMI, rather maximal allowed weight measurements. As usual (IMHO), the Harvard School of Public Health makes a crazy estimation here, namely that waist circumference is best just measured on its own (without regard for hip measurement or heaven forbid height) because it’s easier. And therefore, women’s waist sizes should be less than 35 inches. So my 6 foot tall office manager with a 35 inch waist is almost obese and someone who tops out at 5 feet tall, with a 34 inch waist is better off? Rants over.
Increased abdominal fat is well estimated by comparing waist circumference to height: if your waist measures over half your height, you likely have excess abdominal fat, which is likely to be the physiologically active and dangerous visceral fat, deposited around your organs rather than just under your skin. Only a CT scan, though, can tell for sure. No big fan of the overuse of x-rays and CT scans, I do think it’s worth getting a scan for body fat if there is a question or if someone is looking for motivation to start a fat loss (not a weight loss) program. Increased abdominal fat is strongly associated (and some of the physiology understood) with an increased risk of type 2 diabetes, cardiovascular disease, some cancers, and death.
Small intestinal bacterial overgrowth (SIBO), however, is probably just as prevalent, but more difficult to identify. I have a high index of suspicion in a variety of circumstances: complaints of burping, bloating or borborygmi (fancy name for rumbling) after eating; a history of osteoporosis, unexpected anemia, food poisoning, irritable bowel diagnosis or travelers’ diarrhea; and use of medications such as steroids, antibiotics and particularly the drugs that block the production of acid by the stomach. Testing is done fairly easily, at home with a special kit. Treatment is a bit more challenging (discussed in my article here) but is important to restore normal nutrient absorption in our vital small intestine.
The overlap in conditions noted in this journal article raises several interesting questions. Can SIBO, noted for malabsorption and weight loss, actually be responsible for weight gain? Does it particularly cause abdominal weight gain? Or does the association go in the other direction: do elevated levels of glucose and insulin (causative in abdominal fat gain), increase the risk of SIBO? Of course, it is also possible that it is a complete coincidence and not related by cause in any way. (If red cars are involved in more accidents than white cars: is it the temperament that chooses red? Or the mind-set that chooses white? Or are red cars somehow accident magnets. We can’t tell. Thanks to Dr. Michael Eades for that example. You can probably think of one yourself.)
My takeaway from this study is that I will raise the question when I see one of these conditions: is the other condition present? They both need attention.