WASHINGTON — A majority of consumers were confused about portion size and serving size in a survey of 1,000 US adults presented Jan. 26 by the International Food Information Council. Less than half of respondents correctly identified the terms.

Serving size is based on the amount of a food or beverage typically consumed in one sitting. Portion size is the amount of a food or beverage someone chooses to eat in one sitting.

Washington-based Lincoln Park Strategies conducted the online survey of consumers aged 18 and over from Nov. 4-9, 2021. The survey first asked whether they understood the terms portion size and serving size, with 91% saying they had at least some understanding about serving size and 90% saying the same for portion size.

The respondents then were given a list of possible definitions for both terms and asked to pick out the descriptions that aligned with their understanding.

Among those claiming at least some understanding of serving size, 48% picked the correct definition and/or thought the company that created the product defined serving size. Another 33% said they thought serving size was the amount one chooses to consume, which is the definition for portion size.

Thirty-nine percent said they thought dietitians and health professionals defined the term serving size, and 33% said they thought government agencies such as the Food and Drug Administration defined the term.

Among those claiming at least some understanding of portion size, 45% correctly identified the term while 48% said it was a standard amount typically consumed, which is the definition for serving size. Forty-four percent said dietitians and health professionals define the term portion size.

When asked how they try to control their portion sizes, 34% said they try to eat more slowly, 34% said they try to stop eating once they feel full, 32% said they use smaller plates/bowls and 31% said they choose single-serve portions. Seventeen percent said they do not pay attention to portion sizes, with consumers over age 45 and those making less than $40,000 per year more likely to give that answer.

After being shown the correct definitions of both terms, 34% said they understood the terms much more and 30% said they understood the terms somewhat more.

Men, at 41%, were more likely to say they understood much more after seeing the definitions than women, at 27%. Consumers earning more than $80,000 per year, at 47%, were more likely to say they understood much more than those earning less than $40,000 per year, at 26%. Consumers under age 45, at 43%, were more likely to say they understood much more than those of the ages 45 to 64, at 26%, and those older than 65, at 25%. Consumers with college degrees, at 40%, were more likely to say they understood much more than those without a college degree, at 28%.