February 8/Washington -- Adding lower-calorie food and beverage items to their menus has contributed to sales growth at major fast-food and sit-down restaurant chains, a study released this week by the Hudson Institute shows.

Over a five-year period, the policy research organization found that restaurants that had added lower-calorie foods to their menus saw a 5.5% average increase in same-store sales. Ironically, those chains offering none or who had decreased their number of low-calorie menu items saw a 5.5% average decline in sales growth, according to the research. “Lower-calorie” items were defined as those containing less than 500 calories.

Traffic also was seen to increase at restaurants that had added low-cal items. Those restaurants experienced a boost in total traffic of 10.9% from 2006 to 2011