In the 1950s an average meal of a cheeseburger, French fries and soda pop would be about 600 calories, slightly under one third of the total calories an average person needs in one day.  If you eat that same meal today, you’re likely to consume more than 1,200 calories in one sitting – over half of your daily needs!  Why such a significant calorie difference for the same meal?  The answer: portion distortion.

Compare the difference in serving size (and calories) of some food and drinks 20 years ago versus today:

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Without a doubt, larger food and drink portions significantly affect our eating habits. While common sense may tell you that you simply eat until you feel “full” regardless of how much or little you are served, in fact research studies show that when people are given more food, they tend to eat more of it, even past the point of feeling full.

Satiety (the sense of feeling “full”) is not only a result of the actual amount of food we eat but is also affected by other visual and psychological factors. For example, sometimes it’s not about how much food is on our plate but how filled the plate looks. Studies have shown that people who ate a meal that fills up a small plate reported feeling more “full” compared to those who ate the exact same meal on a large plate (it looked like less food).

Of course, satiety also depends on the food itself since some foods fill you up more than others.  Just think about how much oatmeal you can eat compared to popcorn.  In general, foods that are high in fiber (like whole grains, fresh vegetables and fruits) increase satiety.  Also, because it takes your body longer to digest and absorb protein and fat compared to refined carbohydrates (white bread, white rice), high-protein and high-fat foods keep you feeling full.

So, what exactly are the proper portions?  How do I know what’s too much or too little?  In order to provide a frame of reference for food portions, standard serving sizes have been developed by the USDA as part of their Dietary Guidelines for Americans.  For example, one carbohydrate serving refers to one slice of bread, ½ cup of cooked rice or ½ cup of cooked pasta.  One fruit serving is one medium-size apple or banana.

Proper portions of some foods are easier to visualize than others.  For example, what exactly does a three-ounce serving of meat look like?  Associating portions with common objects may help:

3 ounces = 1 deck of cards or the palm of your hand

1 cup = 1 tennis ball

1 ounce or 2 tablespoons = 1 golf ball

However, it’s still hard to picture how much spinach is considered one cup.  Browse our portion gallery (from the USDA Dietary Guidelines for Americans) and see standard serving sizes for various foods including fruits, vegetables, grains, dairy, meats and nuts & beans.

Note: This information is not intended to take the place of advice from a health professional. Check with your physician before starting any diet or exercise program. While all efforts have been made to ensure the information included in this material is correct, new research is released frequently and may invalidate certain pieces of data. 3/07.