If you have not gotten into shape for your bathing suit yet, you might as well give up. The truth is that very few people past the age of 11 look good in bathing suits. There is something quite good -- sporty and wonderful -- about the rest of us wearing them anyway. It shows that we defy those who value surface beauty only, that our self-worth goes deep enough that we don't mind exposing that extra pinch of flesh in the name of comfort or sport or bathing, or whatever. And we are grateful for the caftan.

I've never thought a bathing suit was a particularly good reason to eat lightly in summer. But feeling good is; feeling lean and mean and better able to cope with the hot ponderous air that we will live with for the next two months. The rules for summer cooking (quick preparation time, low to no hot-oven time) can fit in nicely with the rules for light eating (lots of vegetables, low-fat dishes and summer's wonderful fresh fruits).

Salads are the obvious solution to summer eating, but they're by no means easy to make and even if you try to vary them with a red pepper here and an artichoke heart there, they can take on a kind of sameness that makes you long for a bacon cheeseburger after a week or so. Salads are most interesting in summer when they are served for dinner, loaded with onion rings, pepper rings, hard-cooked eggs and tuna flakes. If the family cook is serving a salad dinner to the man of the house, she can have a most lascivious low-fat lunch for herself: six cold boiled fresh shrimp, a huge pile of marinated string beans, and a slice of zucchini bread, plus a tall icy glass of one of those new mineral waters touched with fruit flavor.

Although I love vegetables, I've always had a problem with them in summer, which is that I hate to stay inside washing, peeling and chopping them when I'd much rather be outdoors hanging around on the deck, soaking in the shadows of late afternoon and watching the kids play. This summer, I've licked the problem by taking the knife, cutting board and vegetables right out to the deck. I have even mashed avocados and grated cheese out there. You just have to be careful where you put the knife down.

Now that I can prepare foods outdoors in the prehistoric way, and cook them in the microwave oven in the space-age way, I can make this wonderful vegetable casserole in mid-summer without getting all hot and bothered about it. Or any fatter.

The stuffed tomatoes make a pleasant ladies' lunch or hot night dinner, the beef tartare balls are a supper surprise for the weary warrior home from a day of slaying dragons, and the pineapple shake is for those mornings when it's already incredibly hot when you get out of bed. PINEAPPLE BREAKFAST SHAKE (1 serving)

1/2 cup very cold water

1/2 cup nonfat dry milk

1 egg

1 teaspoon sugar

1/2 teaspoon vanilla

1/4 of a fresh pineapple, cut into chunks

3 ice cubes

Place all ingredients except ice in a blender and process until smooth. Add the ice cubes one at a time and blend until each one no longer rattles. Serve immediately. RED, WHITE AND GREEN CASSEROLE (6 servings)

3 teaspoons olive oil

2 medium onions, sliced 1/4-inch thick

1 pound potatoes, peeled and sliced 1/4-inch thick

6 small zucchini, sliced 1/2-inch thick

2 large ripe tomatoes, cut into cubes

2 peppers (one red, one green) sliced into strips

2 garlic cloves, chopped finely

2 tablespoons chopped parsley

1 tablespoon chopped fresh fennel or 1 teaspoon fennel seed

Salt and pepper to taste

Drop a teaspoon of oil into the bottom of a shallow glass or ceramic baking dish (lasagna-pan size) and rub around with a paper towel. Arrange half the onion slices on the bottom.

Combine the remaining ingredients in a bowl (except the onions and the oil); season with salt and pepper and spread over onions.

Spread the remaining onion rings over the top and drizzle with the olive oil. Cover with plastic wrap and microwave for 20 minutes, or until all the vegetables are tender. If using a conventional oven, cover with foil and bake at 350 for 1 1/4 hours, removing foil and cooking uncovered for an additional 15 minutes. TOMATOES STUFFED WITH EGG SALAD (2 servings, 2 tomatoes each)

4 large tomatoes

2 hard-cooked eggs, chopped

1 cup bread crumbs

4 teaspoons low-fat mayonnaise

2 teaspoons plain yogurt

1 teaspoon curry powder

2 tablespoons chopped fresh basil or 1 teaspoon dried basil

Salt and pepper to taste

Core the tomatoes and cut away about one quarter of each from the stem end. Scoop out the tomato pulp, chop and drain liquid. Salt the inside of the tomato shells and drain them upside down on paper towels for 30 minutes.

In a bowl, combine the drained pulp, chopped eggs, bread crumbs, mayonnaise, yogurt, curry powder, basil and salt and pepper to taste. Stuff inside the tomatoes, top with tomato "lids" and serve. BREAST OF CHICKEN HUNTER STYLE (4 servings)

2 teaspoons oil

4 split chicken breasts, skinned and boned

1/4 cup sliced mushrooms

1 tablespoon thinly sliced scallions

1/2 cup dry white wine

1 cup chicken bouillon

1 tablespoon chopped parsley

1/2 cup peeled, chopped tomato

Drop oil in a skillet and rub around with a paper towel; saute' the breasts until light brown. Remove and add mushrooms and scallions to the skillet; saute' 1 minute. Add wine, cook a minute longer, and add bouillon with parsley and tomato. Add chicken and simmer until slightly thickened. Cover and place in a 350-degree oven for 10 minutes, or microwave on high for 5 minutes. BEEF TARTARE BALLS (4 small servings)

1 pound lean ground sirloin

1 egg yolk, beaten

1 teaspoon finely chopped onion

1 teaspoon salt

Freshly ground pepper to taste

Chopped parsley to taste

Mix the meat, egg, onion and salt and pepper. Form into individual balls, roll in chopped parsley and serve immediately.