Answer:
A key part of healthful eating means choosing appropriate amounts of different foods. When it comes to deciding how much to eat, the terms serving size and portion size are often used interchangeably. However, they don't mean the same thing.
Serving size is a standardized amount of food. It may be used to quantify recommended amounts, as is the case with the MyPlate food groups, or represent quantities that people typically consume on a Nutrition Facts label.
Portion size is the amount of a food you choose to eat — which may be more or less than a serving.
For example, the Nutrition Facts label may indicate ½ cup cereal for one serving but if you eat ¾ cup, that is your portion size.