With spring comes the familiar resolve to lose weight and improve body tone. Warmer temperatures promise impending bathing-suit weather. Everyone knows that slow weight loss means toning now to fit into summer clothes.

Perhaps that's why dieticians nationwide have chosen March as National Nutrition Month. With current emphasis on physical fitness as a part of overall health, D.C. area dieticians are centering nutrition month activities around exercise and sound eating habits.

Among the events planned in this area for National Nutrition Month is a lecture on weight loss in the meeting room on the first floor at Tysons Corner Center on Thursday from 9 a.m. to 12:15 p.m.

For a $2 registration fee, participants can hear internist Dr. Arthur Frank and nutritionist Mary Archer talk about achieving and maintaining ideal weight. From 10:30 a.m. to 11, 62-year-old Marguerite Miller will demonstrate how yoga contributes to mental and physical fitness. Afterward, home economist Cheryl Brower will demonstrate cooking nutritious meals in a microwave oven, followed by a demonstration on how to cut chicken "to cut costs and calories."

No nutrition lesson would be complete without recognizing the U.S. dietary guidelines. As established by the U.S. Department of Agriculture, they are:

* Eat a variety of foods

* Maintain ideal weight

* Avoid too much fat, saturated fat and cholesterol

* Eat foods with adequate starch and fiber

* Avoid too much sugar

* Avoid too much sodium

* If you drink alcohol, do so in moderation

For those who look to their microwave ovens to produce meals that are fast as well as nutritious, the following menu should prove helpful. While many people know that the microwave oven reduces cooking time, fewer realize another great attribute: easy cleanup.

Wine gives the following recipe (and many recipes with gravy or sauce) extra flavor. Substitute a lesser amount (1 tablespoon) of sherry or vermouth if you have it on hand. Cut the saltiness of the sauce by using low-sodium chicken bouillon granules instead of standard bouillon. An optional "bouquet" or browning sauce -- commercially available -- gives the sauce extra color.

The chicken dish contains about 200 calories per portion. Served with 1/2 cup cooked rice (brown if possible -- this is nutrition month) and 1/2 cup fresh or frozen peas, the entire meal weighs in at about 350 calories.

It is assumed that every kitchen is equipped with flour, sugar, salt, pepper and some kind of oil or butter.

EXPRESS LANE LIST: boneless chicken breasts, mushrooms, wine, chives or tarragon, lemon, chicken bouillon, rice, peas.

MUSHROOM CHICKEN (4 servings) 2 tablespoons white wine 2 teaspoons dried chives or 1 teaspoon tarragon 1 pound boneless chicken breast halves (4 halves)$$8 ounces fresh mushrooms, sliced 1/2 cup water 2 tablespoons all-purpose flour 2 teaspoons lemon juice Freshly ground pepper to taste

% teaspoon chicken bouillon granules 1/8 teaspoon browning sauce (optional)

Combine white wine and chives. Set aside. Place chicken breasts in elongated ceramic or glass baking dish. Cover with sliced mushrooms. Cover the dish with waxed paper and microwave on medium power (50 percent) for 5 minutes. Rearrange the breasts (for even cooking), turn the dish and cook on medium power 4 minutes more. Remove from oven and pour any juices into wine-herb mixture. Return to oven, turning dish, and cook on medium power 4 more minutes. Remove breasts to large plate. Combine remaining ingredients, including wine mixture, in baking dish with mushrooms and microwave on high power for 2 minutes (or until thickened), whisking once or twice to insure even cooking. (This sauce will cook from the outside of the dish toward the center. Brisk whisking blends the thicker with the thinner portions.) Place breasts back in cooking dish and microwave 1 to 2 minutes to heat through. Serve sauce-covered chicken with hot rice and cooked peas.

Note: This recipes yields chicken breasts that are just past pink. Those who prefer well-done chicken should increase the cooking time a couple of minutes.