At one time, jaw wiring was a widely publicized method for treating serious weight problems. I have not heard much about it recently. Is it considered effective?

Jaw wiring initially produces dramatic results. But over the long haul -- which is what really counts -- it does not seem to be effective, especially considering the discomfort of the procedure.

One study several years ago compared the weight loss from jaw wiring to two other methods. The first was a crash diet and comprehensive weight-management program. The second was token treatment consisting of instruction about weight management.

In this study, 39 men and women had their jaws wired for six months. Meantime, in the comprehensive weight program, 68 subjects of both sexes, all in their 40s and averaging 70 percent overweight, enrolled in a day-care center for six weeks. During that time, they ate a diet of just 600 calories a day. After that they were seen once a week for an indefinite period. The third group consisted of 16 men and women who were given two 45-minute interviews and written instructions based on the content of the more comprehensive program.

The group with their jaws wired lost much more weight at the outset, with the women averaging 46 pounds. But the dropout rate was highest in this group. After four years, those study members who could be traced -- who presumably were the more successful ones -- showed a net weight loss of just under 21 pounds.

The women in the comprehensive diet program had a better record after two years -- with a loss stabilizing at 27 pounds.

Even those who received only the minimal treatment averaged a 15-pound loss after one year.

These study results demonstrate that jaw wiring -- an extreme and uncomfortable measure -- may cause large weight losses in the beginning, but does not offer long-term advantage.

Last year you printed instructions for freezing tomatoes. Unfortunately, a friend told me about this only after our home-grown tomatoes were gone. I thought I had written down the directions, but cannot find them. The growing season is just beginning, and this time I would like to be prepared. Can you tell me how it is done?

While people who preserve food at home generally think about canning tomatoes, they are also frozen quite easily. Unlike a number of other vegetables, they do not contain enzymes that cause overripening during freezing. Therefore they need not be blanched. Simply pour boiling water over the tomatoes to allow the skins to slip off easily. Then pack them in freezer-weight plastic bags for later use in any dish requiring cooked or canned tomatoes.

According to Dr. Gertrude Armbruster of the New York State College of Human Ecology at Cornell University, analyses of tomatoes preserved by this method have higher levels of ascorbic acid than canned tomatoes, even after they have been in the freezer for a year.

In a recent column on dieting, you mentioned a reduced-calorie pasta salad. You said to mix the pasta with lightly steamed vegetables and to use yogurt instead of oil, mayonnaise or sour cream as the main moistener. It sounded like a good idea, but can you give me more specific instructions?

It is up to you to choose the vegetables for this delicious dish. Some need not even be steamed. You can simply blanch, by pouring boiling water over them and then letting them sit for 3 or 4 minutes. Included in this group are green beans, small broccoli or cauliflower florets, asparagus shoots (if they are still available) and tender summer squashes, such as yellow crookneck and zucchini. On the other hand, carrots and turnip are among those which you might want steamed a bit.

As for the dressing, just thin some low-fat yogurt by whipping in a little lemon juice and milk, and then add seasonings. Fresh dill and chopped scallions are a good choice. Dijon mustard and tarragon leaves make another tasty combination. Or, for an Oriental flavor, try soy sauce, minced garlic, a bit of sesame oil and a dash of Chinese hot pepper oil.

We find that pasta-twists or small shapes seem to work best.