Todd discusses a study in the New England Journal of Medicine that reviewed weight gain in the U.S. Researchers studied 120,000 well educated adults for 12- to 20 years, and found that on average, weight gain was a little less than one pound a year, or about 17 pounds over a 20-year period. Learn which 5 foods seem most connected to weight gain, and which 5 foods seem most connected to weight maintenance.