Fat can be ugly, fat can be embarrassing, but most importantly fat can kill. According to the 1985 Statistical Abstract of the United States, issued by the Department of Commerce, about 50 percent of deaths are from arterial diseases which include strokes, heart attacks and some forms of kidney failure. Many experts believe that a large factor contributing to these deaths could be a diet high in fats, especially saturated fats.

Dr. James R. Moore and his wife Madeleine of Rockville have written a book about their fears. "Fats in Your Diet: Live a Longer Life" makes a distinction between saturated fat and unsaturated fat, and provides recipes to include a higher proportion of the latter.

"Unsaturated oils," says Moore, a private practitioner, "have the effect of triggering the liver into excreting cholesterol and bile salts into the intestine, thus lowering the cholesterol level."

On the other hand if you consume too much polyunsaturated fat, some evidence shows you could increase your risk of cancer. "So don't go out and gulp a whole bottle of safflower oil." Adds James, "The key is moderation."

Moore thinks a 3-to-2 ratio of polyunsaturated fat to saturated fat is the best (the average American's ratio is 2 to 5).

The Moores began writing the book about 1 1/2 years ago. James explains why. "As an internist I see a tremendous number of people who are dying of arterial disease and a very large percentage of them have an elevated level of cholesterol."

"We became very interested in heart disease," says Madeleine Moore, "because the men on my husband's side of the family have had many bypasses. And since we have two sons, aged 21 and 22, we thought it would be a good idea to find out more about it."

Madeleine, whose job was to compile the book's extensive lists, including guides to weights, measures and substitutions, and sodium data, and to create appropriate recipes, says she modified many existing recipes by making a few quick adjustments.

"For one egg, I substitute 2 egg whites. I use oil instead of margarine or butter. One of the lists I compiled is a conversion to oil. I use skim milk. After a while these choices become second nature."

In addition to the P:S ratio, each recipe includes data for calories, grams of fat, grams of saturated fat and grams of polyunsaturated fat because, James says, "many people don't understand the ratios so we insisted on writing the real honest-to-goodness numbers to help them."

To order the book, write MHM Publishing, 6105 Tilden La., Room 10-D, Rockville, Md. 20852 and send $8.95 plus $1 for postage and handling. Maryland residents add 45 cents for sales tax.

But if you'd like to change your habits for the better immediately, try this recipe from the book -- it is delicious and requires just a short trip through the express lane before completion.

EXPRESS LANE: safflower oil, chicken breasts, chicken broth, chinese plum sauce, cider vinegar, pineapple chunks, sesame seeds. CHICKEN BREASTS SESAME (4 servings)

1 tablespoon safflower oil

2 whole chicken breasts, boned, skinned and cut into cubes

2 tablespoons chicken broth or bouillon, preferably low sodium

1/4 cup Chinese plum sauce

2 tablespoons sugar

1 tablespoon cider vinegar

20-ounce can pineapple chunks, drain and reserve liquid

2 tablespoons sesame seeds

Heat oil in skillet and stir-fry chicken for about 10 to 15 minutes. Add broth or bouillon. Cover and cook over medium heat 2 to 3 minutes. Mix plum sauce, sugar, vinegar, pineapple and 3 tablespoons of the reserved liquid. Add to skillet and mix well. Heat just until mixture is thorougly heated. Sprinkle with sesame seeds.