People with higher heart rate variability have a ticker that adapts strongly to physical activity, stress and other demands. Laboratory animals subjected to caloric restriction have been shown to live 30 to 40 percent longer than those on standard diets. Now it has become evident that middle-aged people practicing restricted calorie intake have the cardiovascular health of people 20 years younger.
Heart rate variability and aging
As the cardiovascular system becomes less flexible with age, heart rate variability declines. Poor heart rate variability is associated with a higher risk of cardiovascular death. Researchers at Washington University School of Medicine in St. Louis have found that heart rate variability declines very slowly in people who have been significantly cutting calories for an average of seven years.
Calorie cutting CRONies
In the world of nutrition science, people who practice caloric restriction are known as CRONies (Calorie Restriction with Optimal Nutrition). The researchers hooked portable heart monitors to 22 CRONies averaging age 52 who ate healthy diets but took in 30 percent fewer calories than normal—about 1,400 a day. The CRONies were compared with 20 others about the same age who ate standard Western diets.
The CRONies had heart rates significantly lower than the Western diet group and their heart rate variability was significantly higher. Researchers also compared the CRONies with normal levels of heart rate variability among people of different ages and found they have hearts that look and function as if they were years younger.
Because the autonomic nervous system controls the heart, their robust heart rate variability also indicates that the CRONies have better health in general. This is due to the fact that in addition to heart function, the autonomic nervous system also affects digestion, respiratory rate and a host of other involuntary functions.
Less calories, longer life?
But Phyllis K. Stein, PhD, lead author of the study, published online in the journal “Aging Cell,” said it’s not absolutely clear that caloric restriction is the sole reason for the flexibility of the CRONies cardiovascular systems. “People who practice CR tend to be very healthy in other areas of life too,” she said. “These people are very motivated and they tend to engage in a large number of very healthy behaviors.”
The CRONie research suggests that caloric restriction with optimal nutrition does indeed affect humans in similar ways to the lab animals living 30 to 40 percent longer. People who practice calorie restriction sincerely believe they will live significantly longer. But it will take several more years to find out if that is actually true.