Call it metabolic magic: Eating fewer calories reduces the risk of chronic diseases like heart disease and diabetes — even among people who are already at a healthy weight.

The two-year project with the National Institutes of Health found that it’s not just weight loss that improves healthy levels of cholesterol, blood sugar, blood pressure and other markers of health. Eating fewer calories than the body uses triggers some metabolic signal or “magic molecule.”

Many markers for metabolic disease improved — including a reduction in a biomarker of chronic inflammation, a red flag for heart disease, cancer and cognitive decline.

To get them ready for the test diet, participants ate three meals a day during the first month of the Duke Health study that reduced their usual calorie intake by 25 percent. They chose from six different meal plans that accommodated cultural preferences or other special needs. In addition, they attended group and individual counseling sessions for six months.

People were asked to stay on the calorie-reduced diet for two years. Their success with that varied, and in the end the average calorie reduction was about 12 percent. Even at this rate they were able to maintain a 10-percent weight loss, over 70 percent of which was fat loss. After two years, many markers for metabolic disease improved — including a reduction in a biomarker of chronic inflammation, a red flag for heart disease, cancer and cognitive decline.

“There's something about caloric restriction, some mechanism we don't yet understand that results in these improvements,” researcher, William E. Kraus, of Duke University, said in a statement. Now the goal is to drill down to figure out exactly what it is that brings these impressive benefits. “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.”

A smaller reduction in calorie intake than that attempted in the study would still reduce the prevalence of diabetes and cardiovascular disease in the U.S., said Kraus. Being mindful of little dietary indiscretions or reducing the number of them could add up to significant calorie savings. Even if you are at a healthy weight, or just a few pounds away from your ideal weight, you can further improve your metabolic health by eating about 300 fewer calories each day.

Consider these dietary blunders that will run up your calorie intake and are pretty easy to cut out of your diet on most days:

  • Small bag of chips – 160 calories;
  • Six Oreo cookies – 300 calories;
  • One bag M&M candies – 230 calories;
  • 12-ounce soda – 150 calories;
  • One cup of ice cream – 300 calories;
  • 16-ounce can Red Bull – 230 calories.

    • Start thinking about what you can do without to improve your long-term health.

    The study was published in The Lancet Diabetes & Endocrinology .