When it comes to reducing the risk factors for diabetes, heart disease, and stroke, cutting even a moderate amount of calories can serve as a powerful remedy to the ravages of poor and unhealthy diets, according to a new study published July 11 in the medical journal The Lancet Diabetes & Endocrinology.
LSU’s Pennington Biomedical Research Center’s leading obesity researchers, Drs. Eric Ravussin and Leanne Redman, served as clinical principal investigators of the study. Duke University served as the coordinating center for the study, and Dr. William Kraus, a cardiologist and distinguished professor of medicine at Duke, was the study’s lead author.
Cutting caloric intake by around 12 percent, or 300 calories per day, for two years significantly reduced multiple cardiometabolic risk factors, even for healthy young and middle-aged men and women, researchers found.
In addition, calorie restriction improved already normal risk factors in healthy young and middle-aged study participants, implying improvement in long-term cardiovascular risk. The study’s findings should provide a new tool for clinicians in fighting the ravages of the 21st-century American lifestyle, the researchers said.
“To our knowledge, this trial is the first, adequately powered two-year dietary randomized clinical trial to show such a profound effect on lowering all cardiometabolic risk factors beyond normal levels, even in rather young, lean individuals,” Ravussin said.
“There are no pharmacological agents with such a profound effect on such a broad range of cardiometabolic risk factors,” Redman said.
In the study, 220 healthy, normal weight men and women were randomly assigned to either a calorie-restriction group or one where volunteers followed their normal diet. Pennington Biomedical’s clinical trials unit enrolled more than a third of the participants from the Baton Rouge area. The calorie-restriction group cut their consumption by the equivalent of a traditional cake donut, from an average of 2,467 calories to 2,170.
Participants in this ongoing project with the National Institutes of Health called CALERIE* were also enrolled through Washington University Medical School in St. Louis, Missouri; and Tufts University in Boston.
The risk factors that improved with calorie restriction were waist circumference, blood pressure, HDL-cholesterol, LDL-cholesterol, triglycerides, insulin resistance and glucose control, metabolic syndrome, and chronic inflammatory tone. The improvements placed the calorie-restriction group well below the conventional risk thresholds used in clinical practice.
For example, the participants began the study with a higher concentration of a biomarker (high-sensitivity C-reactive protein) that indicates chronic inflammation, which is associated with heart disease, cancer, cognitive decline, and the biology of aging. After two years of calorie restriction, the participants’ reduced the biomarker to the range associated with a 50 percent lower risk of heart disease.
The new study is part of an ongoing National Institutes of Health clinical trial called CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy). CALERIE is the first study to focus on the effects of long-term calorie restriction in humans.
“These findings are of substantial public health importance even when started in people who are healthy, young and middle-aged, and not obese,” the researchers said. “These data combined with previously published safety data for calorie restriction, indicate that inexpensive and safe dietary interventions, such as moderate calorie restriction, can be implemented early in life to optimize cardiometabolic health and reduce the lifetime risk of developing some of the most common, disabling, and expensive chronic diseases, such as hypertension and atherosclerosis and cardiovascular disease.”
The researchers said it will be important to do additional research in this area to understand the physiological and molecular biological factors by which the cardiometabolic risk reductions are achieved. Understanding these mechanisms could lead to new prescription drugs to treat these health issues.
This work was supported by the National Institute on Aging and National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under award numbers U01AG022132, U01AG020478, U01AG020487 and U01AG020480, the NIA/NIH Cooperative Agreement AG20487, NIH General Clinical Research Center RR00036, Diabetes Research Training Center DK20579, NIH Clinical Nutrition Research Unit DK56341, and NIH AG00078.
The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.