The growth in snack foods being consumed at meal time is largely driven by people who are eating alone, according to an online survey of over 350,000 snack times a year by market research firm NPD Group. Last year, the average American eating alone consumed a snack food as a meal 191 times, up from 167 times in 2011, equating to billions more snacks (and calories) every year. (This includes potato chips that are eaten alongside a main meal or just the potato chips as a meal replacement; the study didn’t distinguish the kinds of snacks.)

Smaller households and people eating alone are two of the key contributing factors, says Darren Seifer, NPD food and beverage industry analyst. The proportion of one-person households increased to 27% in 2012 from 17% in 1970, U.S. Census Bureau data found. In 2011, there were 32 million one-person households versus 23 million in 1990. In 2012, one-in-five adults ages 25 and older had never been married, a separate analysis of census data by the Pew Research Center found. In 1960, only about one-in-10 adults in that age range had never been married.