Now, predicting the risk of developing heart disease and diabetes is as simple as using an Internet crystal ball.

The online metabolic calculator developed by a University of Virginia School of Medicine doctor and his research partner at the University of Florida predicts patients' risk of developing heart disease and diabetes more accurately than traditional methods, a large new study has found.

The tool's creator hopes it will prompt patients to make lifestyle changes that would spare them the suffering and expense of avoidable illnesses.

"This boils it down to telling a patient, 'On the risk spectrum, you are here, and you're in a position where we're worried you're going to have a cardiovascular event in the next 10 years,'" explained researcher Mark DeBoer. "My hypothesis is that the more specific information you can give to individuals at risk, the more they will understand it and be motivated to make some changes."

The metabolic crystal ball weights the traditional risk factors and also takes into account race, gender and ethnicity to produce an easy-to-understand metabolic severity score.

A small study previously found that the online calculator's predictions lined up well with actual cases of cardiovascular disease and diabetes, and the large new study further bears that out: The study looked, retroactively, at outcomes in more than 13,000 people and found that DeBoer and Gurka's tool was a better risk predictor than the individual risk factors alone.

"This would suggest that when somebody has this congregation of metabolic syndrome findings, there probably is some underlying process that is producing those findings, and that those underlying processes are also contributing to future risk," DeBoer said.

He added, "The hope is that a scoring system like this could be incorporated in the electronic medical record to calculate someone's risk and that information could be provided both to the physician, who then realizes there is an elevated risk, and to the patient, who hopefully can start taking some preventative steps."

The study appears in the Journal of the American College of Cardiology.