My mother, in her early 50s, has gained quite a bit of weight over the past five years. We have a strong family history of diabetes, and I'm concerned. So far she has not responded to my pleas to lose weight. Do you have any facts I could use to motivate her?

ANSWER - If numbers are effective, we think she might be persuaded. Recently, Dr. G.A. Colditz of the Channing Laboratory, Harvard Medical School, and his colleagues analyzed data from the ongoing Nurses' Health Study that began in 1976. At the time, the nearly 114,000 women enrolled were between 35 and 55 years old.The researchers examined the relationship between body mass index (BMI), a measure of fatness estimated from a ratio of weight to height, and incidence of diabetes. The results are quite clear. When it comes to controlling risk of diabetes, the odds favor lighter women. Indeed, even women with an "average" BMI (no more or less lean than half the middle-aged female population) face considerably greater risk of developing diabetes than do women who are a bit lighter. And as BMI goes up, the risk continues to rise.

Beyond that, weight gain after age 18 was a major factor in predicting risk. Among women who gained 22 to 44 pounds, risk increased nearly five-fold, among those who gained 44 to 77 pounds, more than 11-fold, and for those who gained even more, 17-fold.

In the United States at present, diabetes is the seventh leading cause of death and a major risk factor for coronary heart disease and stroke. We hope these data, along with evidence that losing weight reduces risk, will provide your mother with the motivation she needs, and we wish her luck in striving to lose unwanted pounds.

By the way, in case you're wondering why women of "average" weight should be at increased risk, it's because average weights are based on data from the population. As weights increase nationwide, so, too, does the average. In other words, average and ideal simply aren't the same thing.

QUESTION - What are mono and diglycerides? I understand that fats in foods are triglycerides and I'm concerned about the extent to which these compounds, which seem to be in so many foods, add fat to my diet.

ANSWER - You're correct in pointing out that the fats most commonly found in foods are triglycerides. Chemically, they contain three fatty acids attached to an alcohol called glycerol.

Both mono and diglycerides also occur in foods and are formed during cooking. Commercially, they are produced by heating fats and oils. Their chemical nature makes them very effective as emulsifiers, useful in food production for improving and preserving the texture and consistency of many foods.

For example, they're added to peanut butter to prevent it from separating, while in cake mixes they increase the ability to incorporate air and thereby improve the volume. In a quite different application, they're used in margarine to keep it from splattering when heated. As to your concern, the amounts used are pretty small, and don't represent important caloric additions to your diet.

QUESTION - Are there any nutrients in fresh coconut?

ANSWER - None to write home about - except for calories. A 2-inch square, about half-inch thick, provides roughly 155 calories, comparable calorically to about four teaspoons of vegetable oil. The difference is that unlike that in other oils, nearly all the fat in coconut is highly saturated. Feasting on pieces of coconut quickly adds to your day's intake of both calories and fat.

On the other hand, using a small amount of shredded coconut as a garnish in, say, Indian curry, is a different matter. Calorically, the 2-inch square is the equivalent of a generous half-cup of grated or shredded coconut if measured without packing. If packed in, it's about a third of a cup, or a little more than five tablespoons. Used this way, it comes out to only about 30 calories a serving, which means you get a lot of flavor and texture at a relatively low caloric cost.

1990, Washington Post Writers Group