For a country in which roughly 200 million people are overweight or obese, scientists today have discouraging news: Even those who maintain a healthy weight probably should be eating less.
Evidence has been mounting for years that the practice of caloric restriction -- essentially, going on a permanent diet -- greatly reduces the risk of age-related diseases and even postpones death. It has been shown to significantly extend the lives of yeast, worms, flies, spiders, fish, mice and rats.
Now, in a much-anticipated study funded by the National Institutes of Health, many of the same benefits have been demonstrated in primates, the best evidence yet that caloric restriction would help people.
The findings, published in the journal Science, tracked rhesus monkeys that were on a reduced-calorie regimen for as long as 20 years. The animals' risk of dying from cancer, heart disease and diabetes fell by more than two-thirds.
The study comes as some validation to the cadre of several hundred true-believing Americans who profess to practice caloric restriction in their daily lives. It was also welcomed by scientists who study the biological mechanisms of aging and longevity.
"It adds to the evidence piling up that caloric restriction, independent of thinness, is a healthy way to stay alive and healthy longer," said Susan Roberts of the Human Nutrition Research Center on Aging at Tufts University, who wasn't involved in the study. "Less diseases in old age has to be something most everyone wants."
Is caloric restriction the solution?
"Mild caloric restriction is beneficial to everybody," said Dr. Luigi Fontana, a medical professor at Washington University in St. Louis.
In his examinations of people who have been practicing caloric restriction for an average of 6 1/2 years, Fontana found their heart function was equivalent to those of people 16 years younger.
Though the regimen sounds grueling, it is hardly a starvation diet, experts said.
It typically begins with an in-depth assessment to determine how many calories an individual needs to consume to maintain a healthy weight. Then that number is shaved by 10% to 30%.
People on caloric restriction can eat three meals a day. A typical menu includes cereal with fruit and nuts for breakfast, a big salad for lunch, and dinner featuring lean meat and reasonable portion sizes. There's also room for a couple of snacks and even a small dessert from time to time.
