Fast Food Phil dines on hamburgers, french fries and soft drinks. What seven-letter nutrient is he missing? Students at Yorktown High School in Arlington can type in the right answer on an Apple computer, while playing the game "Nutrition Sleuth," a computerized version of "Hangman."

They also can find out the nutrients that are missing in the diets of Sleepy Sue (iron), Athletic Annie (water), and Bruiser Bill (Vitamin C). (In case you're still wondering, Fast Food Phil needs calcium.)

"Nutrition Sleuth" is part of a nutrition software package developed by the National Diary Council called "Grab A Byte." It is one of many nutrition education programs on the market today, designed to grab the attention of students and develop their awareness about the nutritional qualities of the foods they eat.

Susan Fraser, a home economics teacher at Yorktown, has used the Grab A Byte program in her foods management class since last year. "The response from the students has been just terrific," she says, noting that the program reinforces nutrition concepts taught in the classroom.

During a recent class, students played the "Have A Byte" game on the Dairy Council program, entering codes for up to eight food items in one meal. The program takes into account the age and sex of the students, and analyzes the meal for calories and eight nutrients in the bar graph form.

"Hey, I got a good meal here," commented 15-year-old Debbie Mumma, after viewing the results of her 700-calorie spaghetti and meatball dinner. Fraser pointed out that the tomato sauce provided good measures of vitamins A and C, and Mumma expressed surprise that the spaghetti was not as high in calories as she had thought.

Students also discovered just how "empty" the calories were in some snacks. One student's snacks of a candy bar, ice cream, Coke and an apple added up to 22 percent of the day's calorie allotment and was low in nearly all the nutrients. "The apple saved you," Fraser told the student.

The program did not analyze for sodium, fat or cholesterol content, which might have been an interesting addition, given the fact that one student's breakfast consisted of four eggs and another student ate three-quarters of a pizza for dinner.

The National Dairy Council began developing nutrition software in 1980, as computers became more common in schools.

"Nutrition often deals with numbers, and the computer lends itself beautifully to that," notes Marianne King, manager of materials and program development at the Council's headquarters in Rosemont, Ill.

Many of the "games" in the nutrition programs on the market "fit right into the way I teach nutrition," says Ava Mendelson, a home economics teacher at Ridgeview Junior High in Gaithersburg, who has created her own nutrition board games and would like someday to transfer them into computer games. To students, she says, nutrition is often "very dry, and they turn right off. This is a way to get them more interested." Some of the programs Mendelson uses in her classes:

*Students compete against each other to become the "Grand Snackmaster" by choosing 10 snack-type food items that together add up to less than 1,200 calories.

Accompanying the graphics are interesting sound effects. Students like the "beeps and burps," says Mendelson. "They think that's neat."

*A program illustrating how many teaspoons of sugar are contained in commonly eaten foods like cereals, beverages, desserts and condiments. A cereal bowl half full of sugar cubes "is a real eye-opener" for the students, according to Mendelson.

*Fast food restaurant items are analyzed for calories and nutrients. "They really have no idea what's in fast foods," Mendelson notes.

Mendelson believes one of the major attractions of these and similar programs is that students can relate to them by plugging in the foods they actually eat. "It really gets their attention," she says, adding that even the other teachers in the school enjoy using the programs.