The New York Times reports positive results from the first major clinical study of caloric restriction (funded by America’s National Institutes of Health) in which 143 healthy volunteers ate (on average) 300 calories less each day:
They lost weight and body fat. Their cholesterol levels improved, their blood pressure fell slightly, and they had better blood sugar control and less inflammation. At the same time, a control group of 75 healthy people who did not practice caloric restriction saw no improvements in any of these markers. Some of the benefits in the calorie restricted group stemmed from the fact that they lost a large amount of weight, on average about 16 pounds over the two years of the study. But the extent to which their metabolic health got better was greater than would have been expected from weight loss alone, suggesting that caloric restriction might have some unique biological effects on disease pathways in the body, said William Kraus, the lead author of the study and a professor of medicine and cardiology at Duke University.
“We weren’t surprised that there were changes,” he said. “But the magnitude was rather astounding. In a disease population, there aren’t five drugs in combination that would cause this aggregate of an improvement….” The researchers looked at measures of quality of life and discovered that the calorie-restricted group reported better sleep, increased energy and improved mood…. One question the study could not answer was whether caloric restriction could extend life span in humans the way that it can in other animals… But ultimately, caloric restriction did have a beneficial impact on a wide range of risk factors for diabetes and heart disease, two conditions that cause death and disability for millions of Americans, especially as they get older.
Asked about the study, the chairman of the nutrition department at Harvard’s School of Public Health questioned whether caloric restriction would be practical for most people, given that “we are living in an obesogenic environment with an abundance of energy-dense, nutrient-poor foods that are cheap, accessible and heavily marketed.”