What Should We Eat?

By DENISE GRADY

Published: November 11, 2003

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In a word — less.

More and more people, young and old, in countries rich and poor, are fat and growing ever fatter. If there are limits to obesity, our species seems not to know about them.

A few selected milestones:

¶In 2000, for the first time, the number of overweight people in the world rose to match the number who were underweight and starving: 1.2 billion.

¶A "new and striking" discovery, reported in 2001, was that nearly 25 percent of American women in their 50's had too much body fat to measure in the usual way, by grabbing a fold of skin with calipers that gauge the layer of fat underneath.

¶In the United States, 65 percent of adults and 15 percent of children ages 6 to 19 are overweight, and the fastest growing group of obese people are 100 pounds or more overweight: between 1986 and 2000, their numbers quadrupled, from 1 in 200 adults to 4 in 200. This year, more than 100,000 in that category are expected to undergo drastic surgery that shrinks their stomachs and shortens their intestines to help them lose weight.

¶An Indiana company that used to sell one "triple-wide" coffin a year now sells four or five a month; each can hold a 700-pound corpse.

¶A book published this year, "What Are You Looking At?" describes itself as "the first fat fiction anthology," and its introduction says, " `Fat' has earned its way into the realm of human conditions that concern literary artists."

All this would matter less if being fat was beneficial, or at least safe. But in most cases it is neither. Obesity kills 300,000 people a year in the United States, increases the risks of heart disease, diabetes, stroke and some cancers, and costs the nation $117 billion a year in medical bills and lost productivity. It is on the World Health Organization's list of major global health risks.

There is no denying it: if you eat more calories than your body needs, you will gain weight. But given the opportunity to indulge, few can resist. And many may not even realize that they are overeating.

Counting calories may seem like an old-fashioned approach, given the trendy diets that abound these days, but food is fuel, the body burns it and the laws of physics still apply. For adults, one way to estimate how many calories you need in a day just to maintain your current weight is to divide your weight in pounds by 2.2 (to convert it to kilograms) and then multiply the results by 30. Using that formula, a 150-pound person needs about 2,045 calories a day. Men usually need a bit more than women, and active people more than sedentary ones.

People who start paying attention are often surprised at how fast calories add up, and, unless they eat a lot of vegetables, how little food provides 2,000 calories. A corn muffin or a large serving of French fries can have more than 400 calories, for instance, a cheesesteak sandwich more than 800, two tablespoons of salad dressing close to 200, a chocolate sundae more than 1,000.

To lose one pound, it is necessary to cheat the body of 3,500 calories — say, 500 a day for a week, or 350 a day for 10 days. That means either eating less or burning off calories by exercising. But many people who try to diet fail sooner or later, regaining much or all of the weight they struggled to lose.

Discouraging as it all may seem, the good news is that people who are substantially overweight can benefit from reducing even a little — dropping just 10 percent of one's body weight and sometimes even less can lower blood pressure, cholesterol and the risk of diabetes. There is no universal formula: a diet that creates a calorie debt and that a person can stick with will take off pounds. Recent studies have suggested that even diets relatively high in fat, like the Atkins diet, help people lose weight and do not cause dangerous rises in blood fats, at least in the short term.

Just as obesity can shorten the life span, there is evidence that in rodents, at least, being very lean can lengthen life. Low calorie diets, in fact, are the only reliable means of extending a mammal's life. In rats and mice, carefully balanced diets with about 30 percent fewer calories than the animals would normally eat keep them looking young and healthy well past middle age, and can extend their lives from three years to four, an increase of 33 percent.
At the National Institute on Aging, researchers are studying such diets in rhesus monkeys. It is too soon to tell whether the monkeys will be unusually long-lived, though studies have suggested that they are aging more slowly than monkeys that eat more. In addition, a few, in their 30's, are the equivalent of human centenarians, said Dr. Donald K. Ingram, acting chief of the laboratory on experimental gerontology.

The monkeys look lean but not emaciated, and their skin and fur are healthy, Dr. Ingram said. But they do act a bit hungry. They know when it is time to eat and they wait for their food.

"If you give them more food, they'll certainly eat it," Dr. Ingram said, adding that unlike most rhesus monkeys, which often save food for later by stuffing it into pouches in their cheeks, the calorie-restricted animals eat right away.

The monkeys are being studied because they are close to humans, and researchers hope to learn something about calorie restriction that may enable them to develop medications that will help people fend off some of the ills of aging. The point of the research has never been to apply calorie restriction to people, Dr. Ingram said, noting that researchers generally assume that most people cannot tolerate such a diet.

But Dr. Ingram said that when he stated that assumption recently at a talk he gave, some skinny men in the audience objected, and said they were already living on sharply restricted diets like those described in scientific articles about the animal experiments.

"They said they're doing it, they have the discipline, and it's difficult but not impossible," Dr. Ingram said. "I was a little bit taken aback, but in talking with them, I said, `I'm going to soften how I say that.' When you think about it, 30 or 50 years ago, 60 percent of the population smoked. It's addictive, and people thought it would be impossible to change. But we have reduced it. It's difficult, but not impossible."

But, Dr. Ingram added, the group trying calorie restriction wished him quick success in developing drugs to mimic its effects. They are hungry.