Study Finds Thin Women Have Lowest Risk of Death : Medicine: Best weight for 5-foot-5 female put at 119 pounds. Higher hazard cited even for average weight.

In a major new study that may earn thin fashion models fresh resentment, Harvard Medical School researchers have found that women of average weight have a slightly higher risk of dying than waif-thin, underweight women.

That conclusion, which appears in today’s New England Journal of Medicine, may well discourage many American women, who have dieted and done aerobics in good faith for years. Specifically, the study’s finding that the optimum weight for a 5-foot, 5-inch woman is 119 pounds seemed to many as unfair as it might be unattainable.

But the study’s primary author, Dr. JoAnn E. Manson, who is also co-director of women’s health at Brigham and Women’s Hospital in Boston, emphasized that the research was not intended to further idealize the super-model physique.

“We’ve been trying to emphasize that there is only a modest increase in the risk of premature death among women who weigh less than 150 pounds,” Manson said with audible frustration shortly after she watched TV news coverage of her study.

According to the researchers, the standard target weights for women are too heavy. According to 1990 federal height-and-weight tables, the desirable range for a 5-foot-5 woman is 126 to 162 pounds. But the new research suggests that the healthiest weight range is 110 to 150 pounds.

Referring to women of that height who weigh more than 160, Manson told The Times, “Where women really need to be concerned is in the moderate to overweight range.”

In their study, the researchers used a complex measure of weight called the body mass index.

However, a simpler rule of thumb for other women to estimate their optimum weight range, Manson said, is to add or subtract five pounds for every inch taller or shorter than 5-foot-5. For instance, the range for a 5-foot, 6-inch woman is 115 to 155.

“The lowest mortality rate was observed among women who weighed at least 15% less than the U.S. average for women of similar age,” the researchers concluded.

When compared with the women weighing less than the average, those of average weight carried a roughly 25% added risk of dying, primarily of heart disease or cancer. To put that in perspective, Manson said, out of 100,000 middle-aged women, roughly 480 of average weight would be expected to die in a year, compared to 400 of those weighing under the average.

Manson said that the main conclusion of the study, which tracked the vital statistics and death rates of 115,195 female nurses over 16 years, was that gaining weight over the years appears to be hazardous.

Gaining more than 20 pounds after age 18 was associated with a two to three times increased risk of death from heart disease. Among women who put on 40 or more pounds over the years, the risk of fatal heart disease was seven times that of women whose weight remained the same.

“I think that the main public health point of the study is that the women who had the lowest risk of premature death had stable weight since early adulthood,” Manson said.

The findings, which match the results of similar recent studies involving men, underscore the health risks associated with carrying too many extra pounds. The study’s authors blame about 300,000 U.S. deaths a year on weight-related illness--a figure that places fat second only to cigarettes in deadliness.

About 58 million Americans are considered to be overweight--a condition that has been linked to increased risk of high blood pressure, diabetes, heart disease, stroke and various cancers. The current study goes beyond specific diseases by linking obesity to overall mortality.

The study contradicts previous research that suggested that being thin carried an increased health risk. The Brigham and Women’s researchers found that when they excluded those women whose leanness could be attributed to smoking, drinking and illness, the remaining thin women were the healthiest in the study.

“If you are lean and are healthy there’s certainly no reason to gain weight for your health,” Susan Z. Yanovski, director of the obesity and eating disorders program at the National Institute of Diabetes and Digestive and Kidney Diseases, told the Washington Post. The institute helped pay for the study.

The new study could have an impact on how America looks at its waistline. Americans’ weight has crept up over the decades. The 1990 U.S. weight guidelines published by the Department of Agriculture have been criticized as overly lax. Some weights listed as acceptable in the 1990 report are up to 20 pounds greater than weights for similar heights suggested in similar guidelines published in 1959, according to the new study’s authors. The 1990 guidelines also allowed for weight to increase with age.

“The increasingly permissive U.S. weight guidelines may therefore be unjustified and potentially harmful,” the authors conclude.

The government is preparing new weight guidelines, taking into account the findings of recent studies, that will set lower weight goals.

An editorial by Tim Byers of the University of Colorado School of Medicine reiterated the importance of exercise for controlling weight: “Without regular physical activity, weight control can usually not be achieved. Conversely, regular physical activity can improve longevity, even for those with body mass indexes in the ‘overweight’ range.”

Times wires services contributed to this story.

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

Calculating Your Body Mass Index

Do you weigh more than is good for you? It depends on your body mass index.

A study in today’s New England Journal of Medicine concludes that thinner is usually better. But figuring out where you stand requires calculating your body mass index--your weight in kilograms divided by the square of your height in meters.

Here’s how to figure it out:

First, multiply your weight in pounds by 0.45 to get kilograms. Next convert your height to inches. Multiply this number by 0.0254 to get meters. Multiply that number by itself. Then divide this into your weight in kilograms.

Your answer will probably be a number in the 20s or low 30s. It is your body mass index.

The study found that middle-aged women whose body mass indexes were below 19 had the lowest risk of death.

* For an index between 19 and 24.9, it was 20% higher.

* Between 25 and 26.9, it was 30% higher.

* Between 27 and 28.9, it was 60% higher.

* Over 29, it was double.

Source: Associated Press