You will be sick

on Tuesday

People who tweet when they're ill could act as an early warning system for the spread of disease. Adam Sadilek at the University of Rochester in New York analyzed 4.4 million tweets tagged with GPS location data from more than 630,000 users in New York City.

By focusing on tweets that appeared to mention illness, he was able to predict when healthy people would fall ill - as confirmed by their subsequent tweets -- up to eight days in advance, with about 90 percent accuracy.

Such information could one day power a smartphone app that warns you when you are anywhere with a high incidence of flu. The findings were revealed at the Conference on Artificial Intelligence in Toronto, Canada, in July.

Harmful belly fat

Someone with a lot of belly fat has a higher risk of death than those who are obese, a new study suggests.

"We knew from previous research that central obesity is bad, but what is new in this research is that the distribution of the fat is very important even in people with a normal weight," said Dr. Francisco Lopez-Jimenez, senior author on the study and a cardiologist at the Mayo Clinic, in a statement. "This group has the highest death rate, even higher than those who are considered obese based on BMI. From a public health perspective, this is a significant finding."

The results of the study were presented at the European Society of Cardiology conference called the ESC Congress 2012.

The researchers looked at almost 13,000 adults from the National Health and Nutrition Examination Survey study by the U.S. Centers for Disease Control and Prevention (cdc.gov/nchs/nhanes.htm), an on-going national health study. Information on the people's size, weight, circumference and other data were measured against death data.

They found that those who had normal BMI but a lot of belly fat had the highest risk of death from all causes. The risk of cardiovascular death was 2.75 higher and death from all causes was more than 2 times higher for these people vs. those with normal BMI and normal amounts of belly fat.

The doctors said those with normal BMI should have a waist-to-hip measurement to determine whether they have too much belly fat. And they should take lifestyle steps to improve their numbers.

Pay lower health costs

Fit middle-age adults have medical costs 38 percent lower later in life, compared with their unfit counterparts, according to a study that analyzed data from Medicare and insurance claims.

Researchers from the University of Texas-Southwestern Medical Center and the Cooper Institute screened more than 20,000 men and women, average age 51, from the Cooper Center Longitudinal Study, which collected data over four decades. Levels of fitness were determined by a treadmill test in which better performance is correlated with regular exercise.

The least-fit group at the study's onset had higher risk factors: 31 percent of the men smoked, compared with 9 percent in the most-fit men, and about 5 percent had diabetes, compared with less than 2 percent of the most-fit men; similar results were found in women. However, even in subjects with risk factors, better fitness in middle age predicted lower medical costs later in life.