No matter how safe any food is for the IBS diet, eating a huge portion of it in one sitting can trigger an IBS attack. Your gastrocolic reflex gains strength in direct correlation to the number of calories you consume in a meal.
While this makes it easy to see why high fat foods causes IBS problems (fat is more than twice as calorie-dense as carbohydrates and proteins) it also means that bingeing on anything carries serious risks for those of us with IBS. So don't kid yourself that when your friends break out a pint of Chunky Monkey and a spoon for that video you're watching, you can do the same with fat-free sorbet. It's not just ingredients when it comes to the IBS diet, but quantity too. Size really does matter.
Keeping your portions small has some fringe benefits, particularly in that it should make it easier to eat more frequently, and this is a helpful strategy for maintaining a constant intake of soluble fiber, and thus stabilizing IBS. Unfortunately, Americans have gotten used to "supersizing" just about everything they eat, and this can be a hard habit to break. One thing to try at home is serving yourself on salad plates and soup bowls, so that visually you don't feel faced with a skimpy meal.
Remember too that you can always take a second small portion after you finish the first one, as long as you eat at a slow-to-moderate pace and you still feel hungry. This is a great way to keep from over-serving yourself initially and then feeling obligated to eat everything on your plate even if you're full (a "don't waste food" lesson ingrained in most of us as children).
Snacking on small amounts of food throughout the day will keep you from getting ravenous and then over-eating, which can trigger an IBS attack. At restaurants, make a point of dividing your plate in half the moment you're served and take that portion home with you for a later meal. Once you develop this IBS diet habit you'll likely be astonished to realize how oversized most restaurant meals are, and it will be clear why it's so common to suffer an IBS attack if you eat all that food at one sitting. I have a few favorite restaurants (Ethiopian and Middle Eastern) whose dinner portions are so generous I actually get three complete meals out of them. Even someone without IBS is likely to feel pretty uncomfortable if they down that much food at a one dinner.
There's another aspect to portion control that has some happy possibilities for the IBS diet. The risk of IBS trigger foods can be tremendously minimized if they're eaten in tiny quantities following soluble fiber. In this regard, it is as much how you eat for IBS as what you eat that will help you manage your IBS symptoms. While this is most important as a tool to allow you to incorporate all those healthy insoluble fiber foods as often as possible, it's also a means of treating yourself to a "mini-splurge" every once in a while. Let's say you're well-stabilized and just dying for a Snickers. Eating a full-size candy bar as a snack when your stomach is empty will likely wreak havoc and send you into an immediate downward spiral of IBS attacks (why? because it's sky high in fat and dairy, and has very little soluble fiber).
However, if your IBS symptoms were well under control and you instead decided to treat yourself to a snack-size individual Snickers bar (a tiny portion equals a tiny quantity of fat/dairy triggers) for dessert, immediately following a nice low-fat, high soluble fiber meal, you'd likely do just fine. I eat solid chocolate almost every day in this manner. (Of course, this may just be sheer willpower because as God is my witness I will not go through life without chocolate, but I think this is probably the less likely explanation.)
Whatever your favorite IBS trigger food, this diet strategy gives you a good means of allowing yourself the occasional small indulgence. IBS food intolerances are, fortunately, not like food allergies, where the quantity of a trigger (say, peanuts) may not matter. For this we can thank our lucky stars, as it means that few things are truly forbidden to us on the IBS diet as long as we follow some common sense rules and exercise a little self control. Now, where's that Hershey's kiss I've been saving?
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