When Not to Eat Fiber

Click, *slam*, click, *slam* - it's that all-too-familiar sound at triathlons - the constant hinging of the porta-potty doors. With a line-up longer than the free doughnut giveaway at Krispy Kreme, the outdoor bathroom section of a triathlon is a place of constant movement, in more ways than one. How come?
One of the body's reactions to exercise is to decrease blood flow to the intestines, which can cause food to accumulate in your gut and draw in excess fluid. This excess fluid moves into the intestine, and can cause bloating and diarrhea. Throw in stress butterflies, gastric jostling as you rush about the transition area, and possible dehydration, which also reduces blood flow to the gut, and you're set-up to make a serious offering to the porcelain god (or very shallow and small plastic toilet, as the case may be).
In a move that drastically compounds this problem, many triathletes follow
the "race like you train" rule and eat a pre-race meal that closely parallels what they've used year round in training. Of course, for many athletes, this list includes: oatmeal, apples, bananas, high fiber bars like Power Bar Harvest, Cliff Bar, or Fig Newtons, and a laundry list of other items that would be classified as high-fiber foods.
A high-fiber diet *does* provide benefits to endurance athletes, allowing for regular bowel movements, weight control, increased prevalence of complex carbohydrates, decreased fat absorption, and increased low-calorie dietary bulk. But on race day, the last thing you want is your pre-race meal knocking on the door to the outside world...5 minutes before the starting gun fires. This is mentally disturbing, physically uncomfortable, and can lead to dehydration and impaired race performance - not to mention you staring down into a bottomless pit of bluish-brown sludge donated by previous athletes.
So what to do? As many as 2-4 days before the race, begin to gradually decrease fiber consumption. If you frequently eat salads, make them smaller. Cut out a piece of fruit. Switch from oatmeal to whole wheat pancakes or whole grain toast. Since you should be tapering anyways, the slight decrease in caloric intake will be insignificant. Make sure to top off your muscle and liver glycogen stores before the race with an adequate pre-race dinner to which your body is accustomed. It should be assumed that prunes, plums, and flax seed scattered over a big bowl of bran cereal and washed down with a handful of raisins is not the answer. I prefer a bowl of whole wheat pasta with a small serving of meat and vegetables, like a marinara sauce with a few pieces of sliced chicken and tomatoes.
Then wake up in the morning and *don't eat fiber*. For a sprint distance race, most athletes will be fine with a 100 calorie gel taken 5-10 minutes before race start. For an Olympic distance or longer, something more substantial is sometimes necessary. I tend to have a sensitive stomach, so my pre-race meal is either A) a liquid diet - usually 300-400 calories of Hammer Gel Perpetuem, sucked down 2-3 hours before the race, then topped off with a quick snack of gel or sip of energy drink before the start or B) one large sweet potato, with just a very small amount of peanut butter or almond butter.
If you tend to visit the bathroom several times before a race, try cutting fiber. This is the one time not to eat it. On race day, leave the stinky, cramped spaces to the prune lovers.

by Ben Greenfield