How to estimate portions

An essential part of calorie counting is accurately estimating portion sizes. It is not difficult to do when you eat at home, but determining portions when you eat out is a bit harder.
Research shows that people of all ages, education levels and body weights erroneously underestimate their food portions by 20 to 200 percent. The United States Department of Agriculture (USDA) finds that adults typically underestimate consumption of grains, sweets and fats, and overestimate fruit, milk products, and servings of meat, poultry, fish, dry beans, eggs, and nuts. When it comes to vegetables, women overestimate and men underestimate their servings.
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