According to CNN:
According to the article, the most recent data available show that 54 percent of adults who live in NYC are overweight or obese.
Chain restaurants already must make the calorie counts of their menu items publicly available, but beginning March 31 they will have to put the numbers on menu boards and menus. The change will affect restaurants with 15 or more outlets — roughly 10 percent of all city restaurants, according to a news release from the city's health department.
The Department of Health argued in October that "calorie information provided at the time of food selection would enable New Yorkers to make more informed, healthier choices."