- Enzyme deficiencies: When your intestines lack enzymes to metabolize specific foods like milk or grains or beans, the food remains undigested so you start feeding your intestine's ravenous bacteria. The result: lots of intestinal dilation and more gas than a Hummer fuel tank. The most common of these is lactose intolerance (the lack of GI agreement with dairy products), and a close second is an allergy to gluten from wheat (and rye and barley—nutritional good guys). As an example, when you lack the enzyme lactase, lactose in the milk reaching your intestine is not metabolized by you, so it's presented to your intestinal bacteria, which metabolize the lactose in your intestines, producing a lot of gas.
- General GI disorders: Problems like irritable bowel syndrome are caused by sensitive nerves and result in inflammation in the intestinal walls. For example, we usually all pass the same amount of gas a day (about 14 times, or 1 liter total), but some of us sense discomfort from that gas more than others.
- Psychological responses: Food aversions can develop if, say, a person had a bad vomit-causing shrimp dinner one night. The Pavlovian response would be to associate shrimp dinner with the painful after-effects and to avoid it.
Find out more about this book:YOU: On A Diet Revised Edition: The Owner's Manual for Waist Management