However, the researchers did find that black dieters (with an average weight loss of 4.2 pounds) seemed to have a harder time losing weight than white dieters (with an average of 14.7 pounds).

CNN: When money's at stake, dieters have more weight-loss success

The average vehicle weight has gone up by about 900 pounds over that time, from 3, 200 pounds to almost 4, 100 pounds.

CNN: Fat and fast: High-performance gets big