One-half cup of egg substitute equals about two eggs. Depending on the brand, egg substitutes are made from different ingredients. In many cases, they are lower in fat and cholesterol than regular eggs.
Most commonly, egg substitute is made from egg yolks and is fortified to contain the same amount of protein as a traditional egg. When an egg substitute contains lecithin, it has the same thickening characteristic of eggs and can be used in baking and other cooking projects where the egg is used as an emulsifier. Because many of the nutrients of an egg are contained in its yolk, vitamins such as iron, zinc, thiamin, riboflavin and folate are often added to egg substitutes to match the nutritional value of whole eggs.