We all have eyes bigger than our bellies from time to time, but if you regularly stack up your plate with more food than you can eat, you could be suffering from "portion distortion".
Don't worry though, there are some easy ways to get your perception of portion size, and your diet, back on track.
For example, it may be useful to know that one portion of flaked or puffed cereal should fill a cup that's about the size of your fist.
However, if you're eating a cereal that's more dense such as granola, your portion should be less - perhaps half, or even a quarter of a cup depending on the cereal's density.
When serving a bowl of salad, imagine fitting the leaves into a cup that's about the size of a baseball.
A piece of fruit should also be about the size of a baseball to count as one of your five a day.
When serving meat for one, a portion of lean meat should be about three ounces, which is approximately the size of a deck of cards.
And if you're eating potatoes, avoid mega spuds and opt for one no bigger than your first.
Check out the video above for more tips, including advice on how to spot an over-sized potion when you're dining out.