There are really only a few basic habits we know should help keep people healthy: eating well, exercising, avoiding smoking, and keeping body fat in check.

Turns out a shockingly tiny number — just 2.7 percent — of Americans actually manage all four habits, according to a new study published in Mayo Clinic Proceedings.

The research, led by Paul Loprinzi of the University of Mississippi, used data about the lifestyles of nearly 5,000 US adults from the 2003 to 2006 National Health and Nutrition Examination Survey. (That's the Centers for Disease Control and Prevention's biggest national health survey.)

The researchers zeroed in on information about exercise (whether people got 150 minutes of moderate to vigorous physical activity weekly based on accelerometer data) and smoking status (measured by blood levels of cotinine, a biomarker for tobacco exposure). As for eating habits, the researchers looked at self-reported 24-hour recall data about diet and used the Healthy Eating Index score (an indicator of diet quality that takes into account how many fruits and vegetables people eat, as well as meat, beans, oil, saturated fat, alcohol, and sodium). To evaluate physical fitness, they also looked at body fat percentage.

The researchers also looked at how these behaviors corresponded with biomarkers related to chronic diseases like diabetes and heart disease, including cholesterol and fasting glucose.

The findings were stark.



Only about 38 percent of Americans surveyed had a healthy diet, just 10 percent had a normal body fat level, and fewer than half (47 percent) were sufficiently active. On the upside: 70 percent of adults reported themselves as nonsmokers. But overall, fewer than 3 percent of Americans managed all four healthy lifestyle behaviors. Eleven percent had none.

Generally, the researchers also found, people who had three or four of these behaviors had better biomarker measures compared with those who managed none.

Others have found similarly dismal levels of Americans with healthy habits. In this 2005 article, published in JAMA, only 3 percent of US adults were nonsmokers, had a healthy bodyweight, ate an adequate amount of fruits and vegetables, and regularly exercised.

Both studies also found that no subgroup outperformed the rest, which suggests there's a lot of room for improvement across society.

This new research should be a reminder of how difficult behavior change is, and how addressing society's obesity challenge is going to take more than simply telling people to eat better and exercise more.