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How to Relish the Holiday Without Spoiling the Fundus

By Jennifer Huget
Tuesday, November 25, 2008

You know just what it'll be like. Again.

You'll arrive at the Thanksgiving table with the best of intentions. You're going to sample just a smidgen of each of the offerings laid out there. But who can stop at a smidgen of turkey, stuffing and gravy? Mashed potatoes and candied yams? Buttered rolls and -- best of all -- that green-bean casserole with fried onion rings on top? And then the pies: pumpkin and pecan, both with whipped cream.

You eat and eat and eat.

And all the while you know you'll end up feeling just like the turkey: stuffed.

All you can do is loosen your belt, maybe toss back some Tums, and wait it out.

The good news? No matter how much you cram into it, your stomach is not likely to explode -- though it may take action to relieve the pressure. There'll be a lot going on in your belly while you digest. Here's an account -- based on information provided by Brooks Cash, chief of gastroenterology at National Naval Medical Center, and Lona Sandon, a dietitian at the University of Texas Southwestern Medical Center in Dallas and a spokeswoman for the American Dietetic Association -- of what'll be happening inside you on Thursday.

As you approach the table, taking in its sights and smells, your brain will tell your stomach to get ready. When you begin to eat, food -- which you chew up and soak with saliva -- moves down your esophagus and drops into a pool of hydrochloric acid, enzymes and hormones, which reduce those bite-size chunks to a liquid called chyme. The upper part of the stomach, or fundus, stores food until the lower part, responsible for the mechanical work of digestion, is ready to receive it.

Then your stomach muscle will begin squeezing open and shut about three times a minute like a fist, mashing the food further.

There's some debate among the experts about stomach capacity, but the average stomach ordinarily holds about one or two cups of food. On Thursday it may be contending with twice that amount or much more. To accommodate the added bulk, the stomach stretches like a balloon. If you were accustomed to overeating, frequent expansion and contraction would have exercised this muscle, allowing it to expand more easily, Sandon says.

If not, though, you'll be feeling the discomfort of a muscle stretched beyond its normal capacity.

And that feeling's going to linger. You may fill up with so much fatty food -- which the digestive enzymes are slow to digest -- that you'll delay the process by which your pyloric sphincter (the ring-shaped muscle at the tail end of your stomach) pushes liquefied food into the small intestine, where the nutrients are absorbed.

That fullness may cause you additional misery. If the stomach's too full, its contents may push up against the diaphragm, just below your lungs. If your meal has been especially fatty, the valve between your esophagus and stomach may relax, allowing some liquid to flow back. You might even taste sourness from the acid in your mouth. The pressure and burning add up to what we call heartburn, which has nothing at all to do with your heart.

"If you get so full your stomach can't hold any more, there are only two ways the food can go," Cash says. "The path of least resistance is up." Luckily, he notes, actual vomiting is unusual because "our brains usually tell us to stop eating before that happens."

Once your stomach starts to stretch, it releases hormones that send signals to the brain, announcing that you're full. That's likely to happened fairly early in your meal -- unless you're too busy eating, laughing and giving thanks to pay attention.

Walk, Don't Run

You could take a gentle walk to help get things moving and stimulate peristalsis, the process by which your stomach and other muscles push food down the gastrointestinal tract. Don't run, though! If you exert yourself, your heart will send blood to those hardworking leg muscles and not to your stomach, where it's needed to continue digestion. That could bring the digestive process to a grinding halt.

Or just the opposite: Running on a full stomach can prod your system into accelerating peristalsis, encouraging it to work overtime to expel all that food in a hurry. You might find yourself running -- to the john.

On the other hand, you shouldn't succumb to the urge to just lie down, which would just make your heartburn worse. If you insist on doing so, though, lie on your right side, Sandon suggests; your stomach will hang toward the pyloric canal leading to the small intestine, and gravity will work in your favor.

Burping can help relieve the pressure built up inside you. Most of that gassiness results from your having swallowed air while eating quickly. Next time, don't gulp. And don't think carbonated drinks such as seltzer will alleviate your problem: They simply add to the gas that your body needs to expel.

On a regular day, the food you eat travels down the whole gastrointestinal tract in about 12 to 24 hours, Sandon says. On Thursday it may take longer, given those fatty goodies you gobbled down. That will give you plenty of time to contemplate these suggestions from another American Dietetic Association spokeswoman, Boston University dietitian Joan Salge Blake, for giving your stomach a break.

Thanksgiving Trickery

"You can outsmart your stomach," Salge Blake says. First, as noted above, "fat makes food stay in the stomach longer. To reduce discomfort, trim some of the fat from the meal." Adding lots of low-fat, vegetable-based side dishes is a good place to start, she says, noting that the added fiber, which passes intact through your system because the body can't digest it, will help move food through your system. Finally, she says, since liquid leaves the stomach faster than solids, start your feast with a thin, broth-based (not cream-filled) soup.

Salge Blake's top suggestion for avoiding feeling as bloated as a float in the Thanksgiving Day parade? Instead of putting all the food on the table and having you and your guests descend into a feeding frenzy, be oh-so-civilized and serve courses. Start with that brothy soup, she suggests. Then serve a nice, veggie-filled salad (no croutons, please!) with a low-fat dressing. By the time you've savored the first two courses, she says, "you're not as ravenous and less likely to overeat at that one sitting."

Your stomach will be thankful. And isn't that what this holiday is really all about?

Check out today's Checkup blog, in which Jennifer shares a dietitian's tips for avoiding overstuffing your belly on Thanksgiving. Sign up for our weekly Lean & Fit newsletter by going to http://www.washingtonpost.com and searching for "newsletters." And e-mail your thoughts to Jennifer at checkup@washpost.com.

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