WHAT DO YOU eat when you're training for a race that includes a 2.4-mile ocean swim, 112-mile bike ride and 26.2-mile run? Anything you want.

And Dave Scott -- the winner of the Ironman triathlon in Hawaii on Oct. 9 -- says he eats tofu and rice cakes and brown rice. The 28-year-old Davis, Calif., fitness consultant says people think his diet is pretty weird. "I eat rice every day -- a lot of brown rice." Then he laughs. "I eat about 15 pieces of fruit every day. One day I had 23 pieces."

The Ironman is probably the most rigorous of the country's triathlons. Perhaps there's a consistency in the diets and training routines of those who participated in the Ironman that could help runners getting ready for Sunday's Marine Corps Marathon.

Another Ironman competitor, Arlington resident Dan Murphy, 22, describes his diet as "typical American" and his training schedule and diet are testimony to the resiliency ofyouth. He eats red meat four times a week, eggs once a week for breakfast, drinks whole milk and started eating salad when he began to train for the Ironman -- last April.

To train he ran five to eight miles in the morning and swam or rode his bike at night. The longest he ever ran was 15 miles; his average ride was 1 1/2 hours or so; he'd swim 1 1/2 miles, perhaps. He swam the Potomac to practice for the Pacific swim.

The 6-foot, 151-pound bicycle repairman completed the Ironman in 14 1/2 hours (compared to Scott's nine hours-plus) and went out dancing to celebrate.

Arlington lawyer Ben Kendrick plans to run in the Marine Corps Marathon even after completing a 13-hour Ironman. "I'm not completely burnt out," he says. (This is Kendrick's second Ironman this year; he finished the February race in 15 hours. The Ironman was scheduled twice this year because it is being changed from a winter to autumn competition. Next year, it's scheduled for October.) To train, Kendrick ran 60 miles a week, cycled 250 and swam six to eight.

He spent a lot of his bike training talking Dan Murphy into entering the competition, something he's glad to do with anyone. With conviction just this side of fire and brimstone, he says, "The important thing with the triathlon is that you have three of the very best aerobics we have discovered. The triathlon is the logical extension of the fitness movement. People like what they see and what they see is the well-rounded athlete with a totally tuned body . . . not just the lower portion."

And to nourish that totally tuned body, Kendrick eats grain cereal and fresh fruit for breakfast, a light lunch consisting, perhaps, of a chicken or turkey sandwich and dinner (after running) of high carbohydrates -- breads, grains and fresh produce -- and fresh fish or seafood. And "lots of vegetables," he adds. "I just don't think you can get too many."

He also supplements, especially before the race. Mostly with minerals (potassium, calcium, magnesium and iron) and some vitamins (B complex and C). Before the competition he eats "everything I can get my hands on." Three days before the Ironman "I ate carbos. Bread. Spaghetti. Anything."

Dave Scott, who won the Ironman in 1980, believes that if you feed your body properly "it'll treat you right." He eats no meat, a lot of bananas and apples, cottage cheese, yogurt, quite a bit of bread, tofu and potatoes. He eats no sugar, white flour or processed foods. And he avoids anything with additives.

He says, "Your body's a machine, you might as well treat it right." Feeding it properly helps you train better, he says, and training's the key -- the race itself "is just exhilarating after training . . . just a matter of pushing yourself a little bit harder and not getting bogged down."

If you've trained right, he says, you'll have the morale to finish strong. "If you let the wall hit, it'll hit," he says laconically. "Alberto Salazar doesn't hit the wall."

The important thing is to "find a comfortable rhythm. It's just a matter of blocking out the bad things." The important part of marathon training, he says, is to have smaller objectives that come every two weeks or every month. One or two races a year isn't enough incentive.

Good food keeps him fit enough to train 5 1/2 to 8 1/2 hours a day -- enough to complete a 9-hour, 8-minute, 22-second Ironman (his 1980 Ironman was 9 hours, 24 minutes). He combines different training: interval runs, time trials on the bike . . . He usually trains by himself. The diet, he says, "was no big revelation." He just "moved away from the red meat, ice cream and pie" he used to polish off during his college years. "I do it by choice," he says about his diet. "I'm looking forward to this tofu and these rice cakes," he says, laughing. He knows it's a bit unusual to eat 1/4 pound of plain tofu, rice cakes, five apples and toast for breakfast.

But, he also cooks, he says: "Garbanzo beans, green onions, lots of green onions, tomatoes, maybe a carrot, plenty of white vinegar, cumin, curry, basil, 1/4 cup cottage cheese and plain yogurt."

Wait. He's not finished. Then you put all that in the food processor, whip it up and pour it over the rice. Hot rice? Well, the two pounds of brown rice he cooks in the morning just sort of sits in the pan all day and stays pretty warm . . .

SPAGHETTINI WITH EGGPLANT (2 to 3 servings) 8 ounces mushrooms 6 medium tomatoes, peeled and finely chopped 2 tablespoons olive oil 1 red onion, thinly sliced 2 garlic cloves, minced 1 tablespoon oregano 1 teaspoon dry basil 1/2 pound cooked spaghettini, vermicelli or thin spaghetti Grated parmesan cheese

Chop mushrooms and set aside. Chop tomatoes and set aside in a mesh strainer to drain. Heat oil in a large skillet and add garlic and onion. Cook until the onion softens. Add mushrooms and cook several minutes to evaporate all excess moisture. Add well-drained tomatoes, oregano and basil. Cook about 5 minutes to heat tomatoes through and allow excess moisture to evaporate, but try not to overcook the tomatoes. Pour this over cooked pasta and serve, with cheese if desired.

OATMEAL BREAD (2 8 1/2-by-4 1/2-inch loaves) 1 package active dry yeast 1/4 cup honey 1/2 cup warm water 3 cups rolled oats 1/2 cup bran 1 tablespoon salt 2 tablespoons melted butter 3 cups boiling water 2 cups unbleached flour 3 to 4 cups whole wheat flour

Combine yeast, honey and water in a small bowl and set aside. Combine rolled oats, bran, salt and butter in a large bowl. Pour boiling water over it and set aside to cool to lukewarm. Combine yeast with oat mixture. Add flour (beginning with unbleached) a cup at a time, mixing thoroughly after each addition. When it is too stiff to stir, turn it out onto a floured surface and work in in remaining flour. Place the dough in a greased bowl and let it rise until doubled in bulk. Punch it down and divide it in half. Form into loaves and place in greased loaf pans. Let the dough rise until doubled in bulk. Place in a 375-degree oven and cook for 40 minutes.

ENDURANCE BARS (20 to 24 bars) Bars: 1 cup unbleached flour 1 cup whole wheat flour 2 teaspoons baking powder 1/2 teaspoon nutmeg 3/4 cup butter 1/2 cup sugar 1 egg 1 teaspoon vanilla 2 teaspoons grated orange rind 1/3 cup orange juice 1/2 cup flaked coconut 1 1/2 cups finely grated carrots Icing (optional): 4 to 6 tablespoons softened butter 1 teaspoon vanilla 2 to 3 cups confectioners' sugar 1 teaspoon grated orange rind Orange juice for thinning

Grease 9-by-13-inch baking pan. Sift together flour, baking powder and nutmeg and set aside. Beat butter until fluffy in a medium sized bowl. Add sugar slowly, beating constantly. Beat in egg, vanilla and orange rind. Add flour mixture alternately with orange juice and stir briefly. Stir in coconut and carrots. Pour into prepared pan and bake at 325 degrees for 30 minutes. Cool and ice, if desired.

To make icing combine 4 to 6 tablespoons of softened butter with vanilla, 2 to 3 cups of confectioners' sugar and grated orange rind. Thin to spreading consistency with orange juice.

REVIVER

Adjust this to personal tastes. Marathoners may prefer a more dilute solution. 1 part lemon juice 2 parts orange juice 4 parts apple juice 1 part water

Combine all ingredients in plastic container with a screw top. Freeze overnight. Remove from freezer before leaving for marathon. Drink after marathon. (Prescribed portions: 1/2 gallon per person after training, 1 gallon per person after marathon.)

AMERICAN CAFE'S SESAME NOODLE SALAD (6 to 8 servings) 1 tablespoon salt 1 pound linguine, fettuccine or thin spaghetti 1/4 cup sesame oil 3 tablespoons soy sauce or tamari 1/4 teaspoon black pepper 1/2 sweet red pepper, diced very fine 1/4 cup chopped watercress leaves 1/2 teaspoon chopped garlic

Bring 4 quarts of water to a boil with the salt. Drop in the pasta and cook it for 3 minutes after the water returns to a boil.

Drain the pasta quickly and submerge it in cold water for about 30 seconds. Drain off the water, tossing the pasta to get rid of as much moisture as possible.

Put the pasta in a large bowl and immediately stir in the sesame oil, soy sauce and pepper. Mix in the remaining ingredients.

Refrigerate the salad, preferably overnight. Serve it cold.

VEGETABLE RICE OR JAMBALAYA (4 servings) 1 cup brown rice 2 cups boiling water 1 pound mushrooms, sliced 2 tablespoons butter 2 medium green peppers, seeded and chopped 1 medium onion, chopped 1 rib celery, chopped 2 pimientos, diced 1 1/2 cups fresh or canned tomatoes 3/4 teaspoon salt Cayenne pepper, to taste 1/2 teaspoon paprika 1/4 cup melted butter

Cover rice with boiling water and simmer 40 minutes (or cook according to package directions). Saute' mushrooms in butter until soft and add green peppers, onion, celery, pimientos and tomatoes. Season with salt, few grains cayenne and paprika. Place in a greased baking dish, pour melted butter over all. Bake, covered 30 to 40 minutes.