I love egg nog around the holidays, but not the 170 calories that a half a cup packs - not to mention the extra fat. I take a half a cup of egg nog and mix it into a either a half a cup or full cup of 1% milk. The flavor is almost as strong and it lasts much longer - not to mention is a lot fewer calories.
An easy way to keep your calorie count accurate is to keep a 1/2 cup measuring cup in the pantry next to the cereal boxes. Most cereal calorie counts go by 1/2 cup or 1 cup. With the measure right there you won't accidentally over pour! Use it to measure your milk, rinse & put back on the shelf.