It will usually say some where like this dish serves 6. Then you just calculate by devision. How many ounces = one serving.
They sometimes do this intentionally so people think the product has less calories.
A serving varies from the type of package you buy the food in,and if you bought packaged goods the serving size is on the package. If it's a particular type of fruit or whatever, you can look up the serving size on the internet.
Many times the serving is posted on the container. Eg. Raisen brand 1 serving =1cup. Ideally this information can be found on the three back or side of the container.
Many times the serving is posted on the container. Eg. Raisen brand 1 serving =1cup. Ideally this information can be found on the back or side of the container.
As stated, the serving size is, typically, listed on the package, however, if you're eating a food that's not packaged, you can find serving sizes listed online.
For instance, a serving of meat is 3-4 oz or you can estimate about the size of a deck of playing cards; a serving of rice is about 1/2 cup or the size of a cupcake wrapper. A teaspoon is about the size of a dice; a tablespoon is about the size of the end of your thumb; a pancake, the size of CD, a serving of cheese, the size of a 9V battery, etc.
You can google serving sizes and come with a variety of sites that will give you actual serving sizes for a variety of foods, along with how to estimate, if you're eating out and don't have a way to measure exactly.
Non starchy fresh/frozen veggies are, typically, unlimited in quantity, unless they are covered with cream or cheesy sauces or other high fat coatings.