Lately, I Have taken to looking at other women. Not casually, the way you notice an unusually attractive women, or one who is wearing something particularly striking. No, I have taken to studying other women and to be specific about it, I have taken to studying their waists.

The origins of this fixation date back to August 1979, when Katherine Margaretta Mann was born at Sibley Hospital. She weighed 7 lbs., 15 1/2 oz. I, her mother, weighed -- well, memory does fade. Suffice it to say that I weighed more than I had nine months before Katherine was born. But I wasn't worried. I would do my exercises and be back to normal in three months. After all, didn't my pregnancy and childbirth book assure me that with proper diet and exercise the figure of old could be restored? Not to worry, said I, as the weeks passed into months and the months passed into a year and I was still favoring clothes with elasticized waistbands. But finally there came a point I had been dreading: the point at which I had to buy new clothes and the point at which, alone in the fitting room, I came face to face with the fat side of the human condition. The 10 pounds I had wished away had, instead, taken up permanent residence in an area I used to call my waist. The situation had gone too far. Two months ago, I declared war on my midriff.

I went on a diet. Fortunately, I said to myself the day I started, am not someone who eats desserts. I stopped eating chocolates when I turned 13 and stopped drinking cokes when I was 14 and discovered that the path to a clear complexion is fraught with self-denial. I happen to like fruit and cottage cheese, so dieting, I concluded happily, would entail a minimum of deprivation. I did not discuss my diet, at first, with my family. In case I should want to binge on something, I certainly did not want one of my children watching me with a raised eyebrow and running through the house ratting on me. So I began my diet surreptitiously, confident that in a couple of weeks the 10 pounds would be gone and the old me would be back.

Nothing happened.

I do not like fruit and cottage cheese so much that I can go on eating it lunch after lunch and not have something happen. So I sought expert advice.

"Exercise," was the unanimous verdict. "The only way you can get rid of that," said one friend, eying my midriff and shaking her head, "is by doing situps."

Now I've always been afraid to take up jogging since I was never any good at sports but sit-ups I could do. Hadn't I almost always passed gym?

So I started doing sit-ups. The first day I did three, then I built up gradually so I could do four, then finally five, and 10 and 15. At some point, the resident 14-year old saw me and volunteered to hold down my feet. I was back down to nine. "YOU MEAN YOU CAN ONLY DO NINE SIT-UPS?" he hooted. Then, apparently seeking revenge for 14 years of preceived child abused, he threw himself on the living-room floor and with a gleeful "time me" produced 65 hands-behind-the-head sit-ups in five minutes.

That was the end of my sit-ups in the living room.

It was also the end of my secret diet. Not long after that the 5-year-old gently explained to me that he would not be offering me a piece of his candy. "Why not?" asked I, archly.

"Because you're FAT," he yelled.

I did not take to that kindly. "Look, little friend," I said, with as much control as I could muster, "I weight 10 pounds more than I would like to weigh, but I am not FAT."

I seriously contemplated taking up jogging. I watched people around the neighborhood jogging and people jogging across Key Bridge. I got as far as mentioning that I was considering taking up jogging to my family.

They were not encouraging. "Mom," said the 14-year-old, "be serious."

Dieting, I have decided, is not what it's cracked up to be. It is not a way to lose weight. It is a way to make yourself miserable. You may or may not also lose weight in the process, but miserable you shall most certainly be. nIt is something that is with you constantly, a worrisome, nagging reminder that your body is falling apart. Lunch conversation, instead of beginning with some witty observation about the world, starts out with, "oh, I guess I'll just have the fruit and cottage cheese plate. I'm dieting." You can't go on ordering fruit and cottage cheese without some explanation.

I have gotten to the stage in my diet where it has become a part of me. I have also gotten to the stage of thinking about giving it up. I have gotten to the point of sitting down and saying to myself, 'Okay, you're not 22 anymore. Maybe you have finally reached the age of full growth. Maybe my body was meant to weigh this much all along and I had been artificially thin.'

That is why I have been looking at other women lately, and my informal study has not been very encouraging. People with small waists and flat tummies don't appear to be artificially thin. They do, however, appear to be younger. Maybe, I have thought with horror, what has happened to my waist has nothing to do with Katherine Margaretta. Maybe it has to do with age.

This thought has sharpened my resolve, as they say. The gauntlet is thrown. If I fail in this diet, I will be admitting defeat. I will be resigning myself not just to living a life with 10 pounds more than I want, but I will be admitting that it is there and I can do nothing about it. I will be gaining weight and losing youth.

For someone who wept on the eve of her 29th birtday, losing youth is not something I am looking forward to. Nor, I suspect, will I do it gracefully. So it's back to sit-ups and cottage cheese and fruit, and who knows, if things get desperate, maybe even jogging.

There's a lot more at stake here than I thought.