New data from a two-year trial suggests that cutting the number of calories consumed daily—even for individuals at a healthy weight—reduces chronic inflammation that has been linked to heart disease, cancer and cognitive decline. Small dietary changes can reduce the burden of diabetes and cardiovascular disease.
William E. Kraus, MD, a Duke cardiologist and lead researcher, says a yet-unknown mechanism associated with caloric restriction triggers the improvements. In adults already at a healthy weight or carrying just a few extra pounds, cutting around 300 calories a day significantly improved already good levels of cholesterol, blood pressure, blood sugar and other markers. The findings of the randomized, controlled trial of 218 adults under age 50 are described in a July article in The Lancet Diabetes & Endocrinology
Part of an ongoing project with the National Institutes of Health known as CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy), the trial contributes to the researchers’ hypothesis that the cause is not just weight loss, but a complex metabolic change triggered by consuming fewer calories than the amount expended.
“There’s something about caloric restriction, some mechanism we don’t yet understand that results in these improvements,” says Kraus, a distinguished professor of medicine at Duke. “We have collected blood, muscle and other samples from these participants and will continue to explore what this metabolic signal or magic molecule might be.”
For the first month of the trial, participants ate three meals a day that reduced caloric intake by one quarter to introduce the new diet. They chose from six different meal plans that accommodated cultural preferences or dietary needs. Participants also attended group and individual counseling sessions for the first six months. Members of a control group simply continued their usual diet and met with researchers once every six months.
Participants were asked to maintain the 25 percent calorie reduction for two years, but the average caloric reduction for all participants was about 12 percent. However, this drop contributed to the participants’ ability to sustain a 10-percent drop in their weight, 71 percent of which was fat, the study found.
Researchers found numerous improvements in markers that measure risk for metabolic disease. After two years, participants also showed a reduction in a biomarker that indicates chronic inflammation which has also been linked to heart disease, cancer and cognitive decline.
“This shows that even a modification that is not as severe as what we used in this study could reduce the burden of diabetes and cardiovascular disease that we have in this country,” Kraus said. “People can do this fairly easily by simply watching their little indiscretions here and there, or maybe reducing the amount of them, like not snacking after dinner.”